Baccatin derivatives and processes for preparing the same

Abstract: Disclosed are 13α-(3-substituted-2-hydroxypropionyloxy)-baccatin compounds represented by the formula: wherein R¹ represents a lower alkanoyl group or a protective group for hydroxy group; R² represents a protective group for hydroxy group; R³ represents a lower alkanoyl group; R⁴ represents a substituted or unsubstituted benzoyl group; X represents a substituted or unsubstituted aryl group, a substituted or unsubstituted lower alkenyl group, or a substituted or unsubstituted lower alkynyl group; and A' represents a halogen atom, azido group or amino group, and processes for preparing the same.

Description: BACKGROUND OF THE INVENTION This invention relates to baccatin derivatives which are synthetic intermediates of taxol derivatives useful as an antitumor agent, and processes for preparing the same. It has been known that taxol (chemical name: 4α,10β-diacetoxy-2α-benzoyloxy-5β,20-epoxy-1β,7β-dihydroxy-13α-[(2R,3S)-3-phenyl-3-benzoylamino-2-hydroxypropionyloxy]-tax-11-en-9-one) which is diterpenoid obtained from bark of Taxus brevifolia and N-debenzoyl-N-(t-butoxycarbonyl)-10-deacetyltaxol (chemical name: 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β, 7β, 10β-trihydroxy-13α-[(2R, 3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one) which is a derivative thereof have excellent antitumor activities on ovary cancer and cancers of thymus and others ("Annual Reports in Medicinal Chemistry", Chapter 32, p. 305 (1993)). Among taxane derivatives, a compound in which a side chain at 13-position of a taxane skeleton is hydroxy group has been known as a baccatin compound and named baccatin I-VII or the like depending on a substituent on the taxane skeleton ("Dictionary of Organic Compounds, the 4th edition (the 3rd supplement), p. 506 (1985)). It has been variously attempted to prepare taxol and N-debenzoyl-N-(t-butoxycarbonyl)-10-deacetyltaxol by introducing a side chain into hydroxy group which is a substituent at 13-position of a baccatin compound. There have been known, for example, (A) a method of reacting a baccatin compound with N-benzoyl-3-phenylisoserine in which hydroxy group is protected, in the presence of a condensing agent ("Journal of American Chemical Society", Vol. 110, p. 5917 (1988)), (B) a method of reacting a baccatin compound with a 4-phenylazetidinone compound (Japanese Provisional Patent Publication No. 1782/1994), (C) a method of reacting a baccatin compound with an oxazolidine compound ("Tetrahedron Letters", Vol. 33, No. 36, p. 5185 (1992)) and (D) a method consisting of reaction of baccatin with cinnamoyl chloride and osmium oxidation of the resulting cynnamic ester in the presence of sodium t-butylchlorocarbamate (Japanese Provisional Patent Publications No. 30478/1988 and No. 30479/1988). However, in the above method (A), the reaction time is long and also the yield is low even when N-benzoyl-3-phenylisoserine is used excessively; in the above methods (B) and (C), the preparation of the 4-phenylazetidinone compound and the oxazolidine compound are both complicated; and in the above method (D), the reaction doesn't proceed stereo-selectively or regioselectively so that this method is not good for preparing taxol derivatives. It has been also known that taxol has an excellent anti-tumor activity on various kinds of cancers as mentioned above, but water-solubility is as extremely low as 0.004 mg/ml or less ("Nature", Vol. 346, p. 464 (1993)), which is a clinical problem. In order to improve the antitumor activity and water-solubility of taxol, modifications of various substituents have been carried out in the prior art (Japanese Provisional Patent Publications No. 30478/1988 and No. 30479/1988, "Tetrahedron Letters", Vol. 33, p. 5185 (1992) and "Tetrahedron", Vol. 45, p. 4177 (1989)). As an example of improving water-solubility by modifying hydroxy group in a side chain at 13-position and/or hydroxy group at 7-position of taxol with a hydrophilic group, there may be mentioned, for example, U.S. Patents Nos. 4,960,790, 5,059,699 and 5,283,253, and Japanese Provisional Patent Publication No. 1782/1994. In U.S. Patent No. 4,960,790, there has been described a taxol derivative obtained by modifying hydroxy group in a side chain at 13-position and/or hydroxy group at 7-position directly with a residue obtained from amino acid such as alanine, leucine and isoleucine. In U.S. Patent No. 5,059,699, there has been described a taxol derivative obtained by modifying hydroxy group in a side chain at 13-position with a group such as -CO-(CH y ) n -CO-NH-(CH 2 ) 2 -SO 3 -M (where y is 1 or 2, n is 1 to 3, M is hydrogen atom, an alkali metal or the like, e.g., sodium 4-(2-sulfonatoethyl)amino-1,4-dioxobutyl group). In Japanese Provisional Patent Publication No. 1782/1994, there has been described a taxol derivative obtained by esterifying hydroxy group in a side chain at 13-position, hydroxy group at 7-position and/or hydroxy group at 10-position with phosphoric acid or carbonic acid. Further, in U.S. Patent No. 5,283,253, there has been described a taxol derivative obtained by substituting amino group in a side chain at 13-position by furancarbonyl group or thiophenecarbonyl group and modifying hydroxy group in a side chain at 13-position and/or hydroxy group at 7-position with a carboxyl group-substituted or carbamoyl group-substituted lower alkanoyl group. However, heretofore, it has not been reported that a taxol derivative having high water-solubility, and stability and excellent antitumor activity is used clinically. SUMMARY OF THE INVENTION An object of the present invention is to provide a process for efficiently preparing baccatin derivatives, which are important synthetic intermediates for preparing taxol derivative, by efficiently introducing a side chain into hydroxy group at 13-position of a baccatin compound by the use of a starting compound synthesized in a simple and easy method, and to provide novel synthetic intermediates generated in the course of the above-mentioned preparation. The present invention provides a 13α-epoxypropionyloxybaccatin compound represented by the formula (III): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group, The invention also provides a 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom; X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group; and A represents a halogen atom. Further provided by the present invention is a 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound represented by the formula (V): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group. Additionally the present invention provides a process for producing synthetic intermediates which process comprises a process for preparing a taxol compound represented by the formula (IX): wherein R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, R 5 represents a C 2-7 alkoxycarbonyl group which may be substituted by 1 to 3 groups selected from the group consisting of a halogen atom and a C 1-5 alkoxy group (where said C 2-7 alkoxycarbonyl group may have a 3- to 5-membered cycloalkyl portion), a C 2-7 alkanoyl group which may be substituted by a halogen atom, which may be substituted by 1 or 2 C 1-5 alkoxy groups, an arylcarbonyl group or an aromatic heterocyclic group-substituted carbonyl group; R 11 represents a C 2-7 alkanoyl group or hydrogen atom; and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group, which comprises reacting a 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VI): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 , R 4 and X have the same meanings as defined above, or a salt thereof which is obtained by introducing an azido group to a 13α-(3-halogen-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein A represents a halogen atom; and R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above, and reducing the resulting 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound represented by the formula (V): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above, said compound represented by the formula (IV) being prepared by halogenating a 13α-epoxypropionyloxybaccatin compound represented by the formula (III): wherein R 1 , R 2 , R 3 and X have the same meanings as defined above, said compound represented by the formula (III) being prepared by condensing a baccatin compound represented by the formula (II): wherein R 1 , R 2 , R 3 and R 4 have the same meanings as defined above, and an epoxypropionic acid compound represented by the formula (I): wherein X has the same meaning as defined above or a reactive derivative thereof, said compound (VI) being reacted with a compound represented by the formula (VII): R 5 OH where R 5 has the same meaning as defined above, a salt thereof or a reactive derivative thereof, and removing a protective group from the resulting 13α-(3-acylamino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VIII): wherein R 1 , R 2 , R 3 , R 4 , R 5 and X have the same meanings as described above. The invention also provides certain combinations of the process steps in said process. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, the present invention is explained in detail. In the present invention, as the aryl group of X in the above formulae (I), (III), (IV), (V) and (VI), there may be mentioned an aromatic hydrocarbon cyclic group (e.g., phenyl group and naphthyl group) or an aromatic heterocyclic group (e.g., furyl group, thienyl group and pyridyl group); and as the halogen atom of A in the formula (IV), there may be mentioned chlorine atom, bromine atom and iodine atom. Furthermore, as the protective group for hydroxy group used as R 1 and/or R 2 in formulae (II) to (VI), there may be mentioned a conventionally used protective group for hydroxy group, which can be removed easily according to a conventional method. Specifically, the process of the present invention can be applied suitably when R 1 is a lower alkanoyl group (e.g., acetyl group, propionyl group, butyryl group and pentanoyl group), or a protective group for hydroxy group such as a trihalo-lower alkoxycarbonyl group (e.g., trichloroethoxycarbonyl group) and a tri-lower alkylsilyl group (e.g., trimethylsilyl group and triethylsilyl group); R 2 is a protective group such as a trihalo-lower alkoxycarbonyl group (e.g., trichloroethoxycarbonyl group), a tri-lower alkylsilyl group (e.g., trimethylsilyl group and triethylsilyl group); R 3 is a lower alkanoyl group (e.g., acetyl group, propionyl group, butyryl group and pentanoyl group); R 4 is unsubstituted benzoyl group or a substituted benzoyl group (e.g., a benzoyl group substituted by a lower alkyl group, a lower alkoxy group or a halogen atom); and X is unsubstituted phenyl group, a substituted phenyl group (e.g., a phenyl group substituted by a lower alkyl group, a lower alkoxy group or a halogen atom) or an unsubstituted lower alkenyl group (e.g., vinyl group). Said processes of the present invention can be applied particularly suitably when R 1 is acetyl group or trichloroethoxycarbonyl group, R 2 is trichloroethoxycarbonyl group, R 3 is acetyl group, R 4 is unsubstituted benzoyl group, X is unsubstituted phenyl group and A is bromine atom. In the epoxypropionic acid compound (I) of the present invention, there exist four kinds of stereoisomers [a (2R,3S) type and a (2S,3R) type (trans isomer) and a (2R,3R) type and a (2S,3S) type (cis isomer)] based on asymmetric carbon atoms at 2-position and 3-position. Also in the 13α-epoxypropionyloxybaccatin compound (III), the 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV), the 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V) and a 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI), there exist four kinds of stereoisomers [a (2R,3S) type, a (2S,3R) type, a (2R,3R) type or a (2S,3S) type isomer] based on two asymmetric carbon atoms existing in a side chain at 13-position. The processes of the present invention are applicable to the cases using either of the isomers or a mixture thereof and all the reactions proceed regioselectively and stereoselectively. When (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of epoxypropionic acid compound (I) is used (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of 13α-epoxypropionyloxybaccatin compound (III); (2R,3R), (2S,3S), (2R,3S) and (2S,3R) type of 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V); and (2R,3R), (2S,3S), (2R,3S) and (2S,3R) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI) are obtained, respectively. The present invention can be preferably carried out by the use of (2R,3R) or (2S,3S) type of epoxypropionic acid compound (I) to give (2R,3R) or (2S,3S) type of 13α-epoxypropionyloxybaccatin compound (III); (2R,3S) or (2S,3R) type of 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V); and (2R,3S) or (2S,3R) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI), respectively. In this embodiment, the process in which (2R,3R) type of epoxypropionic acid compound (I) is used to give (2R,3S) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI) is the most preferred. On the other hand, when (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of epoxypropionic acid compound (I) is used (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of 13α-epoxypropionyloxybaccatin compound (III); (2S,3R), (2R,3S), (2S,3S) and (2R,3R) type of 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin derivative (IV); (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V); and (2R,3S), (2S,3R), (2R,3R) and (2S,3S) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI) are obtained, respectively. The present invention can be preferably carried out by the use of (2R,3S) or (2S,3R) type of epoxypropionic acid compound (I) to give (2R,3S) or (2S,3R) type of 13α-epoxypropionyloxybaccatin compound (III); (2S,3R) or (2R,3S) type of 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin derivative (IV); (2R,3S) or (2S,3R) type of 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V); and (2R,3S) or (2S,3R) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI), respectively. The process in which (2R,3S) type of epoxypropionic acid compound (I) is used to give (2R,3S) type of 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI) is the most preferred. The condensation of the baccatin compound (II) and the epoxypropionic acid compound (I) or a reactive derivative thereof can be carried out in a suitable solvent. As the solvent, there may be mentioned an aromatic solvent (e.g., benzene, toluene and xylene), and as the reactive derivative, there may be mentioned an acid halide (e.g., acid chloride, acid bromide and acid iodide), an active ester (e.g., p-nitrophenyl ester) and a mixed acid anhydride (e.g., a mixed acid anhydride with methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid). The condensation of the baccatin compound (II) and the epoxypropionic acid compound (I) can be carried out by using a condensing agent. As the condensing agent, there may be used N,N'-dicyclohexylcarbodiimide, N,N'-carbonyldiimidazole, a di-lower alkyl azodicarboxylate (e.g., dimethyl azodicarboxylate) and a 1-methyl-2-halopyridinium iodide (e.g., 1-methyl-2-bromopyridinium iodide). The condensation is carried out preferably in the presence of an organic base. As the organic base, there may be used an aromatic tertiary amine (e.g., 4-(N,N-dimethylamino)pyridine and N,N-dimethylaniline). On the other hand, the condensation of the baccatin compound (II) and the reactive derivative of the epoxypropionic acid compound (I) can be carried out in the presence or absence of an acid acceptor. As the acid acceptor, there may be used an organic base (e.g., pyridine, triethylamine, N-methylpiperidine, N-methylmorpholine and N-ethyl-N,N-diisopropylamine). The present reaction can be carried out under cooling to under heating and is carried out particularly preferably at 18 °C to 80 °C. The subsequent azido group-introduction to the 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV) can be carried out in a suitable solvent or without a solvent, and the azido group-introduction can be carried out by using a metal aside. As the metal azide, there may be suitably used either an alkali metal azide (e.g., lithium azide, sodium azide and potassium azide) or a tri-lower alkyltin azide (e.g., tri-n-butyltin azide). When the alkali metal azide is used, water, a mixture of water and a hydrophilic solvent (e.g., an alcohol type solvent such as methanol, ethanol, propanol and butanol, and a ketone type solvent such as acetone) or an aprotic polar organic solvent (e.g., dimethylsulfoxide, dimethylformamide and dimethylacetamide) may be used as a solvent. The reaction is carried out preferably in the presence of a base acceptor (e.g., a formate such as methyl formate and an ammonium salt such as ammonium chloride). On the other hand, when the tri-lower alkyltin azide is used, the reaction can be carried out without a solvent and may be carried out by adding an aprotic organic solvent (e.g., dimethylsulfoxide, dimethylformamide and dimethylacetamide), if necessary. The reaction can be accelerated by adding a Lewis acid (e.g., zinc bromide, zinc iodide, tin bromide and tin iodide). The present reaction can be carried out under cooling to under heating and is carried out particularly preferably at 20 °C to 60 °C. The halogenation of the 13α-epoxypropionyloxybaccatin compound (III) can be carried out in a solvent in the presence of a Lewis acid and a halogenating agent. As the Lewis acid, there may be mentioned a titanium halide (e.g., titanium tetrachloride, titanium tetrabromide and titanium tetraiodide), a tin halide (e.g., tin tetrachloride, tin tetrabromide and tin tetraiodide), a magnesium halide (e.g., magnesium chloride, magnesium bromide and magnesium iodide) and a di-lower alkylaluminum halide (e.g., diethylaluminum chloride). As the halogenating agent, there may be mentioned a di-lower alkylamine· hydrohalide (e.g., diethylamine hydrochloride, diethylamine hydrobromide and diethylamine hydroiodide). When a titanium halide, tin halide or magnesium halide is used as a Lewis acid, said compound also acts as a halogenating agent so that it is not necessary to add a halogenating agent. As the solvent, there may be preferably used a mixed solvent of a halogenated hydrocarbon type solvent (e.g., dichloromethane and chloroform), an ether type solvent (e.g., tetrahydrofuran and diethyl ether) or an aromatic solvent (e.g., toluene and nitrobenzene) and an aprotic polar solvent (e.g., hexamethylphosphoric triamide (HMPA), dimethylformamide and dimethylimidazolidinone), and particularly preferred is a mixed solvent of a halogenated hydrocarbon type solvent and HMPA. Concerning of a ratio of the halogenated hydrocarbon type solvent and HMPA to be mixed, when the ratio of the halogenated hydrocarbon type solvent : HMPA is 1 : 0 to 0 : 1, in general, 20 : 1 to 5 : 1, the reaction proceeds suitably. The present reaction can be carried out under cooling to under heating and is carried out usually at -70 °C to 0 °C. The present halogenation proceeds regioselectively and stereoselectively, since opening of the epoxypropionyl group always proceeds by the SN2 mechanism so that using the 13α-(epoxypropionyloxy)baccatin compound (III) in which stereospecific configuration in a side chain at 13-position is (2R,3S) type, (2S,3R) type, (2R,3R) type or (2S,3S) type, the corresponding (2S,3R) type, (2R,3S) type, (2S,3S) type or (2R,3R) type 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV) can be obtained, respectively. The azido group-introduction to the 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV) obtained can be carried out by protecting hydroxy group at 2-position in a side chain at 13-position, if desired, reacting the compound with a metal azide in a suitable solvent in the presence or absence of a metal clathration agent (a metal chelating agent) and removing a protective group when hydroxy group is protected. When hydroxy group at 2-position in a side chain at 13-position is protected, a conventionally used protective group for hydroxy group which can be easily removed by a conventional method may be used as the protective group, and there may be mentioned, for example, a tri-lower alkylsilyl group (e.g., trimethylsilyl group and triethyl silyl group). As the metal clathration agent, there may be used crown ethers (e.g., 1,4,7,10-tetraoxacyclododecane, 1,4,7,10,13-pentaoxacyclopentadecane and 1,4,7,10,13,16-hexaoxacyclooctadodecane), and particularly preferred is 1,4,7,10,13-pentaoxacyclopentadecane. The present azido group-introduction can be also carried out stereoselectively, and 3-position of the 3-halogeno-2-propionyloxy group is substituted by an azido group so that by using the 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV) in which stereospecific configuration in a side chain at 13-position is (2S,3R) type, (2R,3S) type, (2S,3S) type or (2R,3R) type, the corresponding (2R,3S) type, (2S,3R) type, (2R,3R) type or (2S,3S) type 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V) can be obtained, respectively. The 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V) thus obtained or a salt thereof can be converted into a taxol derivative represented by the formula (IX): wherein R 11 represents a lower alkanoyl group or hydrogen atom; and R 3 , R 4 , R 5 and X have the same meanings as described above, (1) by subjecting the compound of the formula (V) or a salt thereof to reduction reaction to obtain a 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VI): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as described above, reacting the compound obtained, with a carboxylic acid compound represented by the formula (VII): R 5 OH wherein R 5 represents a substituted or unsubstituted lower alkoxycarbonyl group (where said lower alkoxycarbonyl group may have a cycloalkyl portion), a substituted or unsubstituted lower alkanoyl group, a substituted or unsubstituted arylcarbonyl group or a substituted or unsubstituted aromatic heterocyclic group-substituted carbonyl group, a salt thereof or a reactive derivative thereof to obtain a 13α-(3-acylamino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VIII): wherein R 1 , R 2 , R 3 , R 4 , R 5 and X have the same meanings as described above, and removing a protective group from the compound obtained; or (2) subjecting the compound of the formula (V) or a salt thereof to reduction reaction in a suitable solvent in the presence of a reactive derivative of the carboxylic acid compound (VII) to obtain the 13α-(3-acylamino-2-hydroxypropionyloxy)baccatin compound (VIII) and removing a protective group from the compound obtained. The taxol derivative represented by the formula (IX) is useful as an antitumor agent and a synthetic intermediate of an antitumor agent, and has been described as taxol, N-debenzoyl-N-(t-butoxycarbonyl)-10-deacetyltaxol or the like in Japanese Provisional Patent Publications No. 30479/1988 and No. 1782/1994, French Patent No. 2698363, PCT Provisional Patent Publication No. 92/09589 and "Bioorganic & Medicinal Chemistry Letters", Vol. 4, p. 2631 (1994). The reduction of the 13α-(3-azido-2-hydroxypropionyloxy)baccatin derivative (V) can be carried out in a suitable solvent. As the solvent, there may be used an alcohol type solvent (e.g., methanol, ethanol, propanol and butanol), an ether type solvent (e.g., tetrahydrofuran and dioxane), acetic acid and a mixed solvent thereof. The reduction may be effected by catalytic reduction in the presence of a metal catalyst (e.g., palladium-carbon) or by using a reducing agent (e.g., triphenylphosphine). Especially, using triphenylphosphine, it is preferred to add a small amount of water. The condensation of the 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound (VI) or a salt thereof with the compound (VII) or a reactive derivative thereof can be carried out in a suitable solvent or without a solvent. Examples of the acid addition salt of the 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound (VI) include formate thereof. As the solvent, there may be used an organic solvent (e.g., a halogenated hydrocarbon type solvent such as methylene chloride, an ether type solvent such as tetrahydrofuran and an aprotic organic solvent such as dimethylformamide). As the reactive derivative of the compound (VII), there may be mentioned the same acid halide and mixed acid anhydride as in the case of the epoxypropionic acid compound (I). The condensation of the 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound (VI) or a salt thereof with the compound (VII) can be carried out by employing the same condensing agent, the same organic base and the same reaction conditions as in the case of condensation of the baccatin compound (II) with the epoxypropionic acid compound (I). On the other hand, the condensation of the 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound (VI) or a salt thereof with a reactive derivative of the compound (VII) can be carried out by employing the same condensing agent, the same organic base and the same reaction conditions as in the case of condensation of the baccatin compound (II) with a reactive derivative of the epoxypropionic acid compound (I). The removal of the protective group from the 13α-(3-acylamino-2-hydroxypropionyloxy)baccatin compound (VIII) can be suitably carried out depending on the kind of the protective group according to a conventional method. When the protective group is a trihalo-lower alkoxycarbonyl group, the protective group can be easily removed by zinc-acetic acid-methanol treatment. When the 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound (V) is reduced in a suitable solvent in the presence of a reactive derivative of the compound (VII), an acid anhydride and a mixed acid anhydride with carbonic acid may be suitably used as the reactive derivative of the compound (VII). As the solvent, there may be suitably used a halogenated hydrocarbon type solvent (e.g., methylene chloride and chloroform) and an aromatic solvent (e.g., toluene and benzene). The reduction can be carried out by using a reducing agent (e.g., triphenylphosphine), and it is preferred to add a small amount of water. The epoxypropionic acid compound (I) which is a starting compound of the present invention can be prepared by hydrolyzing a corresponding epoxypropionic acid ester with a base (e.g., an alkali metal hydroxide) according to a conventional method. Among the corresponding epoxypropionic acid esters, a trans form ester can be prepared by, for example, reacting a substituted or unsubstituted arylaldehyde, a substituted or unsubstituted lower alkenylaldehyde or a substituted or unsubstituted lower alkynylaldehyde with a haloacetic acid ester according to a conventional method of Darzens reaction and carrying out optical resolution, if necessary (Japanese Provisional Patent Publications No. 13775/1985, No. 13776/1985 and No. 15398/1991 and "Journal of Organic Chemistry", Vol. 58, p. 1287 (1993)). On the other hand, a cis form ester can be prepared by, for example, converting a substituted or unsubstituted trans form cinnamic acid ester into a dihydroxy compound by Sharpless asymmetric dihydroxylation to obtain a reactive monoester and then carrying out intramolecular cyclization by base treatment ("Journal of Organic Chemistry", Vol. 51, p. 46 (1986)) or subjecting a substituted or unsubstituted arylaldehyde, a substituted or unsubstituted lower alkenylaldehyde or a substituted or unsubstituted lower alkynylaldehyde and, if necessary, an optically active N-(2-halogenopropionyl)-2-oxazolidinone derivative to aldol condensation according to a conventional method, subjecting the obtained compound to dehydrohalogenation to form an oxirane ring and then removing a 2-oxazolidinone ring by hydrolysis, according to the method described in PCT Provisional Patent Publication No. 92/09589. A taxol derivative represented by the formula (X): wherein R 3 , R 4 , R 5 , X, Z and n have the same meanings as described above and wherein Y is as defined below, can be prepared by reacting a compound represented by the formula (VI-a): wherein R' represents a protective group for hydroxy group, R 2 , R 3 and R 4 have the same meaning as described above or a salt thereof with the compound (VII), a salt thereof or a reactive derivative thereof to obtain a compound represented by the formula (VIII-a): wherein R', R 2 , R 3 , R 4 , R 5 and X have the same meaning as described above, and (1-a) reacting the obtained compound (VIII-a) with a compound represented by the formula (XI-a): Y-Z(CH 2 ) n COOH wherein Y represents a residue obtained by removing hydroxy group of one carboxyl group from an amino acid or dipeptide (where amino group in said residue is protected, and carboxyl group existing in said residue may be protected), Z and n have the same meanings as described above, a salt thereof or a reactive derivative thereof and removing protective groups for hydroxy group from the resulting compound, or (1-b) removing protective groups for hydroxy group from the obtained compound (VIII-a) and the reacting the resulting compound with the compound (XI-a), a salt thereof or a reactive derivative thereof, (2) and, if required, further removing protective group(s) for amino group in Y' from the obtained compound. As the salt of the compound (VI-a), there may be mentioned, for example, an organic acid salt such as formate, acetate, methanesulfonate and p-toluenesulfonate and an inorganic acid addition salt such as hydrochloride and hydrobromide. As the salts of the compound (VII) and the compound (XI-a), there may be mentioned, for example, an alkali metal salt and an alkaline earth metal salt. As the reactive derivative of the compound (VII) and the compound (XI-a), there may be mentioned an acid halide, an active ester and a mixed acid anhydride. As the protective groups for hydroxy group, there may be mentioned, for example, 2,2,2-trichloroethoxycarbonyl group. The reaction of the compound (VI-a) or a salt thereof with the compound (VII) or a salt thereof can be carried out in the presence or absence of a dehydrating agent in a suitable solvent or without a solvent. As the dehydrating agent, there may be suitably used dicyclohexylcarbodiimide, carbonyldiimidazole, 1-methyl-2-bromopyridinium iodide and benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate. As the solvent, there may be suitably used dichloromethane, dimethyl ether, dimethylformamide, dioxane, tetrahydrofuran and toluene. The present reaction proceeds suitably at -20 to 100 °C, particularly 0 to 30 °C. The reaction of the compound (VI-a) or a salt thereof with a reactive derivative of the compound (VII) can be carried out in the presence or absence of an acid acceptor in a suitable solvent or without a solvent. As the acid acceptor, there may be suitably used an alkali metal hydride, an alkali metal carbonate, an alkali metal hydrogen carbonate and an organic base (e.g., triethylamine, dilsopropylethylamine, pyridine, 4-(N,N-dimethylamino)pyridine and 1,8-diazabicyclo[5.4.0]undec-7-ene). As the solvent, there may be suitably used dichloromethane, dimethyl ether, dimethylformamide, dioxane, tetrahydrofuran and toluene. The present reaction proceeds suitably at -20 to 80 °C, particularly 0 to 30 °C. In step (1-a), the reaction of the compound (VIII-a) with the compound (XI-a) or a salt thereof and the reaction of the compound (VIII-a) with a reactive derivative of the compound (XI-a) can be carried out in the same manner as in the reaction of the compound (VI-a) or a salt thereof with the compound (VII) or a salt thereof and the reaction of the compound (VI-a) or a salt thereof with a reactive derivative of the compound (VII), respectively. The subsequent removal of protective groups for hydroxy groups from the resulting compound can be carried out by a conventional method. For example, when said protective group are 2,2,2-trichloroethoxycarbonyl group, zinc-acetic acid may be used for removing them. In step (1-b), the reaction of removing protective groups for hydroxy group from the compound (VIII-a) can be carried out in the same manner as in the removal of protective groups in step (1-a). The subsequent reaction of the resulting compound with the compound (XI-a) or a salt thereof and the reaction of the resulting compound with a reactive derivative of the compound (XI-a) can be carried out in the same manner as in the reaction of the compound (VI-a) or a salt thereof with the compound (VII) or a salt thereof and the reaction of the compound (VI-a) or a salt thereof with a reactive derivative of the compound (VII), respectively. In step (2), the subsequent removal of protective groups for amino group in Y' from the compound obtained in step (1-a) or (1-b) can be carried out by a conventional method. For example, when said protective groups are benzyloxycarbonyl group, palladium-carbon in suitable solvent (for example, tetrahydrofuran) may be used for removing them. In the compound (X), when X is a substituted aryl group, there may be mentioned a halogen atom, a lower alkyl group and a lower alkoxy group as the substituent on the aryl group. As a substituent on the lower alkoxycarbonyl group, lower alkanoyl group, arylcarbonyl group or aromatic heterocyclic group-substituted carbonyl group of R 5 , there may be mentioned a halogen atom and a lower alkoxy group. As an aromatic heterocyclic group portion of the aromatic heterocyclic group-substituted carbonyl group, there may be mentioned an aromatic heteromonocyclic group having sulfur atom, oxygen atom or nitrogen atom as a hetero atom, for example, a 5- or 6-membered aromatic heterocyclic group such as thienyl group, furyl group, pyridyl group, pirazinyl group and pyrimidinyl group. As the lower alkoxycarbonyl group having a cycloalkyl portion, there may be mentioned, for example, cyclopropylmethoxycarbonyl group, cyclobutylmethoxycarbonyl group and (2,2-dimethyl)cyclopropylmethoxycarbonyl group. Further, as an example of the lower alkoxycarbonyl group having a substituent and also having a cycloalkyl portion, there may be mentioned (2,2-difluoro-3,3-dimethyl)cyclopropylmethoxycarbonyl group. In the compound (X), the amino acid of Y includes amino acids from natural or unnatural source and is a compound having each one of at least amino group and carboxyl group in one molecule. There may be mentioned an amino acid from natural source or an antipode thereof, a D- or L-amino acid obtained by synthesis, or a racemic mixture of these amino acids. There may be specifically mentioned an α-amino acid or β-amino acid having amino group on carbon atom at α-position or β-position of carboxyl group or other amino acids. As the α-amino acid or β-amino acid, there may be mentioned a natural amino acid or a non-natural amino acid, and a neutral amino acid, an acidic amino acid or a basic amino acid thereof may be suitably used. As the basic amino acid, there may be mentioned an amino acid having plural amino groups such as asparagine, ornithine and lysine; as the acidic amino acid, there may be mentioned an amino acid having plural carboxyl groups such as glutamic acid and aspartic acid; and as the neutral amino acid, there may be mentioned an amino acid having the same number of amino groups and carboxyl groups such as alanine, isoleucine and leucine. Further, in the present invention, as a specific example of the amino acid which can be used suitably, there may be mentioned glycine, alanine, isoleucine, leucine, valine, glutamic acid, methionine, phenylalanine, proline, β-alanine, arginine, ornithine, serine, threonine, asparagine, aspartic acid, glutamine, cystine, cysteine, tyrosine, histidine, tryptophan, lysine, sarcosine, creatine, homocysteine, norleucine, isoserine, homoserine, norvaline, ε-aminocaproic acid, thioproline, α-aminoisobutanoic acid, piperidylcarboxylic acid, α,γ-diaminobutyric acid, β-aminobutyric acid and γ-aminobutyric acid. Further, as the dipeptide of Y, there may be mentioned a dipeptide comprising the above amino acid, specifically a dipeptide comprising the above natural amino acid or an antipode thereof such as glycylglycine, valylglycine, methionylglycine, prolylglycine, glycylproline, glycylphenylalanine, phenylalanylglycine, glycylvaline, alanylproline, valylproline and phenylalanylvaline. When the amino group and/or carbonyl group in Y is/are protected, a conventional protective group may be used as a protective group. As the protective group for the amino group, there may be mentioned, for example, benzyloxycarbonyl group, tert-butoxycarbonyl group and aminoacetyl group; and as the protective group for the carboxyl group, there may be mentioned methyl group, ethyl group, methoxyethyl, methoxyethoxyethyl and amino group. In the present invention, the lower alkyl group, the lower alkenyl group, the lower alkynyl group, the lower alkoxy group and the lower alkanoyl group mean an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 1 to 5 carbon atoms, an alkynyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms and an alkanoyl group having 2 to 6 carbon atoms, respectively. As the lower alkanoyl group or the lower alkoxycarbonyl group, there may be mentioned, for example, those having 2 to 7 carbon atoms, particularly 2 to 5 carbon atoms such as acetyl group, propionyl group, butyryl group, valeryl group, pivaloyl group, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group and butoxycarbonyl group. As the halogen atom, there may be mentioned chlorine, bromine, fluorine and iodine. Further, in the present specification, the taxane or taxane skeleton represents a diterpene skeleton represented by the following formula. EXAMPLES The present invention is described in detail by referring to Examples and Reference examples. Example 1 (1) Under ice cooling, a solution of 0.504 g of lithium hydroxide monohydrate dissolved in 25 ml of water was added dropwise to a solution of 1.78 g of methyl (2R,3R)-3-phenyl-2,3-epoxypropionate dissolved in 50 ml of methanol. The mixture was allowed to room temperature and stirred for 1 hour at the same temperature. Methanol was removed from the reaction mixture, and the pH of the residue was adjusted to 3 to 4 by adding a 5 % aqueous citric acid solution thereto under ice cooling, and then extracted with chloroform. The chloroform layer was washed with brine and then dried over magnesium sulfate. The solvent was removed under reduced pressure, and hexane was added to the residue. Crystals precipitated were collected by filtration, washed with hexane and then dried to obtain 1.32 g of (2R,3R)-3-phenyl-2,3-epoxypropionic acid. Yield: 80 % m.p.: 81.5 to 83.0 °C IR (nujol) ν max (cm -1 ): 3140, 1750, 1720, 1460, 1200 FAB-MS (m/z): 165 (MH + ) 1 H-NMR (CDCl 3 ) δ: 3.83 (1H, d, J=4.7Hz), 4.31 (1H, d, J=4.7Hz), 7.1 to 7.4 (5H, m), 8.2 (1H, broad s) (2) In 250 ml of toluene were dissolved 1.376 g of (2R,3R)-3-phenyl-2,3-epoxypropionic acid and 4.998 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β,13α-dihydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-tax-11-en-9-one. To the solution were added 1.844 g of N,N'-dicyclohexylcarbodiimide and 0.34 g of 4-(N,N-dimethylamino)pyridine, and the mixture was stirred at 80 °C for 90 minutes. After the reaction mixture was cooled to room temperature, insolubles were removed by filtration, and the solvent was removed from the filtrate under reduced pressure. The residue was purified by silica gel flash column chromatography (solvent: ethyl acetate-hexane (2 : 5)) to obtain 5.734 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3R)-3-phenyl-2,3-epoxypropionyloxy]-tax-11-en-9-one. Yield: 99 % [α] 20 / D = -15.77° (c = 0.9, chloroform) IR (nujol) ν max (cm -1 ): 3500, 1760, 1730, 1460, 1380, 1250, 1060 FAB-MS (m/z): 1039 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.14 (6H, s), 1.58 (1H, s), 1.83 (6H, s), 1.95 to 2.1 (3H, m), 2.39 (3H, s), 2.63 (1H, m), 3.87 (1H, d, J=7Hz), 3.97 (1H, d, J=4.5Hz), 4.14 (1H, d, J=9Hz), 4.30 (1H, d, J=9Hz), 4.33 (1H, d, J=4.5Hz), 4.60 (1H, d, J=11.8 Hz), 4.76 (2H, s), 4.92 (1H, d, J=11.8Hz), 4.97 (1H, m), 5.55 (1H, dd, J=7, 11Hz), 5.63 (1H, d, J=7Hz), 6.03 (1H, m), 6.19 (1H, s), 7.3 to 7.5 (7H, m), 7.64 (1H, m), 8.00 (2H, m) (3-1) In a mixed solvent of 0.3 ml of water and 2.7 ml of methanol was dissolved 105 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3R)-3-phenyl-2,3-epoxypropionyloxy]-tax-11-en-9-one. To the solution were added 0.3 ml of methyl formate and 195 mg of sodium azide, and the mixture was stirred at 50 °C for 40 hours. The reaction mixture was cooled to room temperature and then poured into cold water, and the aqueous mixture was extracted with ethyl acetate. The extract was washed with a 5 % aqueous citric acid solution and then brine and dried over sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by silica gel thin layer chromatography (solvent: ethyl acetate-chloroform (1 : 20)) to obtain 92 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 85 % [α] 22 / D = -16.43° (c = 1, chloroform) IR (nujol) ν max (cm -1 ): 3480, 2110, 1760, 1730, 1460, 1380, 1250 FAB-MS (m/z): 1082 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.20 (3H, s), 1.27 (3H, s), 1.70 (1H, s), 1.86 (3H, s), 2.09 (3H, d, J=1Hz), 2.0 to 2.2 (3H, m), 2.30 (3H, s), 2.63 (1H, m), 3.12 (1H, d, J=8Hz), 3.90 (1H, d, J=7Hz), 4.16 (1H, d, J=8Hz), 4.32 (1H, d, J=8Hz), 4.44 (1H, dd, J=4, 8Hz), 4.61 (1H, d, J=12Hz), 4.76 (1H, d, J=12Hz), 4.82 (1H, d, J=12Hz), 4.92 (1H, d, J=12Hz), 4.95 (1H, m), 5.01 (1H, d, J=4Hz), 5.56 (1H, dd, J=7, 11Hz), 5.68 (1H, d, J=7Hz), 6.22 (1H, m), 6.27 (1H, s), 7.46 (5H, m), 7.51 (2H, m), 7.64 (1H, m), 8.06 (2H, m) (3-2) In 1 ml of tri-n-butyltin azide was dissolved 104 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3R)-3-phenyl-2,3-epoxypropionyloxy]-tax-11-en-9-one at 50 °C. 6 mg of zinc iodide was added to the solution, and the mixture was stirred at 50 °C for 5 days. The reaction mixture was returned to room temperature, purified by silica gel column chromatography (solvent: chloroform) followed by thin layer chromatography (solvent: ethyl acetate-chloroform (1:20)) to obtain 73 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 67 % (4-1) In 4 ml of methanol was dissolved 92 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one, and 47 mg of 10 % palladium-carbon was added to the solution. The mixture was stirred under the atmospheric pressure of hydrogen at room temperature for 2 hours. The catalyst was removed from the reaction mixture by filtration, and the filtrate was concentrated under reduced pressure to obtain 90 mg of crude 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-amino-2-hydroxypropionyloxy]-tax-11-en-9-one. The compound obtained was dissolved in 4 ml of tetrahydrofuran, and 39.7 mg of di-t-butyldicarbonate and 25.5 mg of potassium hydrogen carbonate were added to the solution. The mixture was stirred at room temperature for 19 hours. After diluted with ethyl acetate, the reaction mixture was washed with water and then brine. The organic layer was dried and concentrated under reduced pressure. The residue was purified by silica gel thin layer chromatography (solvent: ethyl acetate-hexane (2 : 3)) to obtain 69 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 70 % [α] 20 / D = -39.0° (c = 1, chloroform) IR (nujol) ν max (cm -1 ): 3440, 1760, 1720 FAB-MS (m/z): 1156 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.20 (3H, s), 1.28 (3H, s), 1.35 (9H, s), 1.71 (1H, s), 1.86 (3H, s), 1.96 (3H, s), 2.01 to 2.12 (1H, m), 2.33 (2H, m), 2.39 (3H, s), 2.56 to 2.69 (1H, m), 3.33 (1H, d, J=5.4Hz), 3.91 (1H, d, J=6.9Hz), 4.18 (1H, d, J=8 Hz), 4.34 (1H, d, J=8Hz), 4.60 (1H, d, J=12Hz), 4.62 to 4.67 (1H, m), 4.78 (2H, m), 4.91 (1H, d, J=12Hz), 4.93 to 4.98 (1H, m), 5.22 to 5.39 (1H, m), 5.38 (1H, d, J=9.4 Hz), 5.55 (1H, dd, J=7, 11Hz), 5.70 (1H, d, J=6.9Hz), 6.17 to 6.25 (1H, m), 6.25 (1H, s), 7.29 to 7.45 (5H, m), 7.46 to 7.54 (2H, m), 7.59 to 7.66 (1H, m), 8.08 to 8.13 (2H, m) (4-2) In a mixed solvent of 5 ml of tetrahydrofuran and 0.2 ml of water was dissolved 92 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one, and 25 mg of triphenylphosphine was added to the solution. The mixture was stirred at room temperature for 18 hours to obtain a reaction mixture containing 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-amino-2-hydroxypropionyloxy]-tax-11-en-9-one. To this reaction mixture were added 39.7 mg of di-t-butyldicarbonate and 25.5 mg of potassium hydrogen carbonate, and the mixture was stirred at room temperature for 19 hours. The solvent was removed from the reaction mixture under reduced pressure, and the residue was purified by silica gel thin layer chromatography (solvent: ethyl acetate-hexane (2 : 3)) to obtain 75 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 76 % (4-3) In 2 ml of methylene chloride was dissolved 57.3 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one, and 36.3 mg of di-t-butyldicarbonate, 26 mg of potassium hydrogen carbonate, 28.5 mg of triphenylphosphine and 0.05 ml of water were added to the solution. The mixture was stirred at room temperature for 20 hours. The solvent was removed from the reaction mixture, and the residue was purified by silica gel thin layer chromatography (solvent: ethyl acetate-hexane (2 : 3)) to obtain 46 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 75 % (5) In a mixed solution of 1.2 ml of acetic acid and 10.8 ml of methanol was dissolved 273 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one, and 544 mg of zinc powder was added to the solution. The mixture was stirred at 60 °C for 2 hours. Insolubles were removed from the reaction mixture by filtration, and the filtrate was concentrated. The residue dissolved in ethyl acetate was washed with 0.01 M hydrochloric acid, 0.01 M aqueous sodium hydrogen carbonate solution, and brine. The oranic layer was dried and concentrated, and the residue was purified by silica gel column chromatography (solvent: ethyl acetatehexane (3 : 2)) to obtain 156 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-phenyl-3-(t-butoxycarbonylamino)-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 82 % [α] 20 / D = -48.37° (c = 0.74, chloroform) IR (nujol) ν max (cm -1 ): 3440, 1720 FAB-MS (m/z): 808 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.13 (3H, s), 1.24 (3H, s), 1.34 (9H, s), 1.58 (1H, br s), 1.69 (1H, s), 1.77 (3H, s), 1.85 (4H, s+ m), 2.27 (2H, d, J=8.7Hz), 2.37 (3H, s), 2.54 to 2.62 (1H, m), 3.37 (1H, d, J=5.5Hz), 3.91 (1H, d, J=7.0Hz), 4.19 and 4.32 (each 2H, d, J=8.5Hz), 4.21 to 4.26 (2H, m), 4.61 (1H, br s), 4.94 (1H, d, J=7.7Hz), 5.21 (1H, d, J=1.7Hz), 5.27 (1H, br d, J=9Hz), 5.43 (1H, d, J=9.3Hz), 5.68 (1H, d, J= 7.0Hz), 6.21 (1H, t, J=9Hz), 7.3 to 7.4 (5H, m), 7.50 (2H, t, J=7.4Hz), 7.61 (1H, d, J=7.4Hz), 8.10 (2H, d, J=7.4Hz) Example 2 (1) Under argon atmosphere, in 70 ml of toluene was dissolved 4.92 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β,13α-dihydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-tax-11-en-9-one. To the solution were added 1.79 g of (2R,3S)-3-phenylepoxypropionic acid, 2.38 g of N,N'-dicyclohexylcarbodiimide and 342 mg of 4-(N,N-dimethylamino)-pyridine at room temperature, and the mixture was stirred for 10 minutes. The reaction mixture was concentrated under reduced pressure, and the residue was purified by silica gel flash column chromatography (solvent: toluene-ethyl acetate (15 : 1)) to obtain 5.55 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-2,3-epoxypropionyloxy]-tax-11-en-9-one. Yield: 97 % IR (nujol) ν max (cm -1 ) : 3520, 1760, 1730 FAB-MS (m/z): 1039 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.21 (3H, s), 1.28 (3H, s), 1.73 (1H, s), 1.86 (3H, s), 2.01 to 2.13 (1H, m), 2.09 (3H, s), 2.20 to 2.41 (2H, m), 2.22 (3H, s), 2.63 (1H, m), 3.64 (1H, d, J= 1.7Hz), 3.92 (1H, d, J=6.9Hz), 4.16 (1H, d, J=8.2Hz), 4.22 (1H, d, J=1.7Hz), 4.32 (1H, d, J=8.2Hz), 4.61 (1H, d, J= 11.8Hz), 4.79 (2H, s), 4.92 (1H, d, J=11.8Hz), 4.94 (1H, m), 5.57 (1H, dd, J=7.1, 10.7Hz), 5.69 (1H, d, J=6.9Hz), 6.27 (1H, s), 6.31 (1H, m), 7.30 to 7.66 (8H, m), 8.07 (2H, m) (2) Under argon atmosphere, 2.70 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-2,3-epoxypropionyloxy]-tax-11-en-9-one was dissolved in a mixed solvent of 50 ml of dichloromethane and 5 ml of hexamethylphosphoric triamide. The solution was cooled by an ice-acetone bath, and 2.80 g of titanium tetrabromide was added to the solution. Thereafter, the mixture was stirred for 18 hours while cooling by an ice bath. 100 ml of water was added to the reaction mixture, and the mixture was stirred for 10 minutes. The organic layer was separated and concentrated under reduced pressure. The residue was dissolved in 50 ml of ethyl acetate, 25 ml of hexane and 50 ml of water, and the organic layer was separated. After the organic layer was further washed with water and dried, the solvent was removed, and the residue was purified by silica gel flash column chromatography (solvent: hexane-ethyl acetate (2 : 1)) to obtain 2.22 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2S,3R)-3-phenyl-3-bromo-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 76 % IR (nujol) ν max (cm -1 ) : 3440, 1760, 1720 FAB-MS (m/z): 1119, 1121 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.19 (3H, s), 1.25 (3H, s), 1.74 (1H, s), 1.81 (3H, d, J=1Hz), 1.85 (3H, s), 2.06 (1H, m), 2.28 (2H, m), 2.39 (3H, s), 2.63 (1H, m), 2.99 (1H, d, J=7Hz), 3.90 (1H, d, J=7Hz), 4.16 (1H, d, J=8Hz), 4.34 (1H, d, J=8Hz), 4.60 (1H, d, J=12Hz), 4.77 (2H, s), 4.78 (1H, dd, J=6, 7Hz), 4.91 (1H, d, J=12Hz), 4.97 (1H, m), 5.27 (1H, d, J=6Hz), 5.53 (1H, dd, J=7, 11Hz), 5.68 (1H, d, J=7Hz), 6.17 (1H, m), 6.21 (1H, s), 7.4 to 7.5 (7H, m), 7.64 (1H, m), 8.07 (2H, m) (3) In 2 ml of dimethylformamide was dissolved 112 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2S,3R)-3-phenyl-3-bromo-2-hydroxypropionyloxy]-tax-11-en-9-one, and 2 mg of 1,4,7,10,13-pentaoxacyclopentadecane was added to the solution. The mixture was cooled by an outer bath at -15 to -10 °C, and 65 mg of sodium azide was added thereto. The mixture was stirred for 18 hours while cooling by an ice bath. The reaction mixture was poured into cool water and extracted with ethyl acetate. The organic layer was washed with brine and then dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by silica gel thin layer chromatography (solvent: ethyl acetate-hexane (2 : 3)) to obtain 77 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 71 % The physical property values were the same as those of the compound obtained in Example 1-(3-1). Example 3 In 2 ml of dimethylformamide was dissolved 100 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2S,3R)-3-phenyl-3-bromo-2-hydroxypropionyloxy]-tax-11-en-9-one, and 0.12 ml of azidotrimethylsilane was added to the solution. The mixture was stirred in an outer bath at 50 °C for 2 hours. 29 mg of sodium azide was added to the reaction mixture, and the mixture was further stirred in an outer bath at 50 °C for 18 hours. The reaction mixture was poured into ice water and extracted with ethyl acetate. After the organic layer was washed with brine and dried over anhydrous sodium sulfate, the solvent was removed under reduced pressure. The residue was dissolved in 5 ml of ethanol. While cooling by an ice bath, an about 15 % hydrogen chloride-ethanol solution was added to the solution, and the mixture was further stirred for 10 minutes. The reaction mixture was poured into ice water and extracted with ethyl acetate. The organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution and then brine and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue was purified by silica gel thin layer chromatography (solvent: ethyl acetatehexane (2 : 3)) to obtain 63 mg of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-phenyl-3-azido-2-hydroxypropionyloxy]-tax-11-en-9-one. Yield: 65 % The physical property values were the same as those of the compound obtained in Example 1-(3-1). Example 4 (1) Under argon atmosphere, a solution of methyl (2S,3R)-2,3-dihydroxy-3-(4-fluorophenyl)propionate (3.95 g, 18.4 mmol) dissolved in dichloromethane (100 ml) was cooled to -3 to -5 °C, and triethylamine (3.86 ml, 27.7 mmol) and p-toluenesulfonyl chloride (3.62 g, 19.0 mmol) were added to the solution. After the mixture was stirred at -3 to -5 °C for 44 hours, the reaction mixture was washed with water and brine. After the organic layer was dried over anhydrous sodium sulfate, the solvent was removed, and the residue obtained was purified by silica gel flash column chromatography (ethyl acetate/hexane = 1/2) to obtain methyl (2S,3R)-3-(4-fluorophenyl)-3-hydroxy-2-p-toluenesulfonyloxypropionate (5.64 g, yield: 83 %). m.p.: 122.5 to 123.5 °C IR (nujol) ν max (cm -1 ) : 3500, 1770, 1140, 730 FAB-MS (NaCl added) (m/z): 391 (M + +Na) 1 H-NMR (300MHz, CDCl 3 ) δ: 2.43 (3H, s), 2.66 (1H, d, J=6Hz), 3.64 (3H, s), 4.88 (1H, d, J=4Hz), 5.11 (1H, t-like), 6.87 to 6.95 (2H, m), 7.17 to 7.25 (4H, m), 7.55 to 7.60 (2H, m) (2) In dimethylformamide (75 ml) was dissolved methyl (2S,3R)-3-(4-fluorophenyl)-3-hydroxy-2-p-toluenesulfonyloxypropionate (5.48 g, 14.9 mmol), and water (1.4 ml, 74.5 mmol) was added to the solution. The reaction mixture was cooled by an ice bath, potassium carbonate (6.16 g, 44.6 mmol) was added thereto, and the mixture was stirred at room temperature for 22 hours. The reaction mixture was cooled again by an ice bath, water (100 ml) was added thereto, and the mixture was extracted with ethyl acetate. The organic layer was washed with brine and then dried over anhydrous sodium sulfate. After the solvent was removed, the residue obtained was purified by silica gel column chromatography (diethyl ether/hexane = 1/3) to obtain methyl (2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionate (2.69 g, yield: 92 %). IR (nujol) ν max (cm -1 ) : 1740, 1510 EI-MS (m/z): 196 (M + ) 1 H-NMR (300MHz, CDCl 3 ) δ: 3.57 (3H, s), 3.82 (1H, d, J=5Hz), 4.24 (1H, d, J=5Hz), 6.99 to 7.07 (2H, m), 7.36 to 7.44 (2H, m) (3) A solution of methyl (2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionate (206 mg, 1.05 mmol) dissolved in 5 ml of methanol was cooled by an ice bath, and a solution of lithium hydroxide (30 mg, 1.26 mmol) dissolved in water (3 ml) was added to the above solution. After the mixture was stirred at room temperature for 1.5 hours, the reaction mixture was concentrated. While cooling by an ice bath, a 5 % citric acid aqueous solution was added to the residue obtained, and the mixture was extracted with chloroform. The organic layer was washed with brine and then dried over anhydrous sodium sulfate. The solvent was removed to obtain (2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionic acid (which was unstable so that it could not be isolated nor purified). Dichlorohexylcarbodiimide (227 mg, 1.10 mmol) and dimethylaminopyridine (14 mg, 0.12 mmol) were added to the solution of (2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionic acid and 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,13α-dihydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-tax-11-ene-9-one (235 mg, 0.26 mmol) in toluene. An outer bath was heated to 80 °C, and the mixture was stirred for 2 hours. Thereafter, insolubles were removed by filtration, and the filtrate was concentrated. The residue obtained was purified by silica gel flash column chromatography (ethyl acetate/toluene = 1/6) to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionyloxy]-tax-11-ene-9-one (167 mg, yield: 60 %). IR (nujol) ν max (cm -1 ): 1760, 1720, 1240, 720 FAB-MS (m/z): 1057 (MH + ) (1059 (MH + +2), 1061 (MH + +4)) 1 H-NMR (300MHz, CDCl 3 ) δ: 1.15 (3H, s), 1.16 (3H, s), 1.61 (1H, s), 1.83 (3H, s), 1.87 (3H, d, J=1Hz), 2.0 to 2.1 (3H, m), 2.36 (3H, s), 2.63 (1H, m), 3.87 (1H, d, J=7Hz), 3.95 (1H, d, J=4Hz), 4.14 (1H, d, J=9Hz), 4.30 (1H, d, J=4Hz), 4.31 (1H, d, J=9Hz), 4.61 (1H, d, J=12Hz), 4.77 (2H, s), 4.92 (1H, d, J=12Hz), 4.97 (1H, m), 5.56 (1H, dd, J=7, 11Hz), 5.63 (1H, d, J=7Hz), 6.01 to 6.08 (1H, m), 6.20 (1H, s), 7.07 (2H, m), 7.39 to 7.52 (4H, m), 7.60 to 7.68 (1H, m), 8.00 (2H, m) (4) Methyl formate (0.7 ml) and sodium azide (432 mg, 6.64 mmol) were added to a solution of 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3R)-3-(4-fluorophenyl)-2,3-epoxypropionyloxy]-tax-11-ene-9-one (235 mg, 0.22 mmol) dissolved in 11 % aqueous methanol (7 ml). An outer bath was heated to 50 °C, and the mixture was stirred for 24 hours. The reaction mixture was poured into ice water and extracted with ethyl acetate. The organic layer was washed with a 5 % aqueous citric acid solution and then brine and dried over anhydrous sodium sulfate. The solvent was removed, and the residue obtained was purified by preparative thin layer chromatography to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-(4-fluorophenyl)-3-azido-2-hydroxypropionyloxy]-tax-11-ene-9-one (162 mg, yield: 67 %). IR (nujol) ν max (cm -1 ): 3480, 2110, 1760, 1720 FAB-MS (NaCl added) (m/z): 1122 (M + +Na) 1 H-NMR (300MHz, CDCl 3 ) δ: 1.22 (3H, s), 1.28 (3H, s), 1.74 (1H, s, D 2 O exchange), 1.87 (3H, s), 2.12 (3H, d, J=1Hz), 2.0 to 2.3 (3H, m), 2.31 (3H, s), 2.65 (1H, m), 3.21 (1H, d, J=8Hz, D 2 O exchange), 3.92 (1H, d, J=7 Hz), 4.18 (1H, d, J=8Hz), 4.33 (1H, d, J=8Hz), 4.42 (1H, dd, J=3, 8Hz), 4.61 (1H, d, J=12Hz), 4.76 (1H, d, J=12Hz), 4.81 (1H, d, J=12Hz), 4.93 (1H, d, J=12Hz), 4.96 (1H, m), 5.03 (1H, d, J=3Hz), 5.56 (1H, dd, J=7, 11Hz), 5.69 (1H, d, J=7Hz), 6.26 (1H, m), 6.28 (1H, s), 7.15 (2H, m), 7.47 (4H, m), 7.63 (1H, m), 8.06 (2H, m) (5) To a solution of 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-(4-fluorophenyl)-3-azido-2-hydroxypropionyloxy]-tax-11-ene-9-one (81 mg, 0.073 mmol) dissolved in dichloromethane (3 ml) were added triphenylphosphine (39 mg, 0.149 mmol), water (0.05 ml), di-t-butyl dicarbonate (48 mg, 0.22 mmol) and potassium bicarbonate (37 mg, 0.37 mmol), and the mixture was stirred at room temperature for 22 hours. The reaction mixture was diluted with chloroform and washed with water and brine. After the organic layer was dried over anhydrous sodium sulfate, the solvent was removed. The residue obtained was purified by preparative thin layer chromatography to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-(4-fluorophenyl)-2-hydroxy-3-t-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (33 mg, yield: 39 %). IR (nujol) ν max (cm -1 ) : 3400, 1760, 1730 FAB-MS (m/z): 1174 (MH + ) 1 H-NMR (300MHz, CDCl 3 ) δ: 1.21 (3H, s), 1.28 (3H, s), 1.35 (9H, s), 1.73 (1H, s, D 2 O exchange), 2.1 (1H, m), 1.86 (3H, s), 1.96 (3H, s), 2.3 (2H, m), 2.36 (3H, s), 2.6 (1H, m), 3.41 (1H, d, J=5Hz, D 2 O exchange), 3.91 (1H, d, J=7Hz), 4.18 (1H, d, J=8Hz), 4.34 (1H, d, J=8Hz), 4.60 (1H, m), 4.60 (1H, d, J=12Hz), 4.78 (2H, s), 4.91 (1H, d, J=12Hz), 4.96 (1H, m), 5.26 (1H, br), 5.36 (1H, m), 5.54 (1H, m), 5.70 (1H, d, J=7Hz), 6.23 (1H, m), 6.25 (1H, s), 7.05 to 7.40 (4H, m), 7.50 (2H, m), 7.63 (1H, m), 8.10 (2H, m) (6) Zinc powder (15 g) was added to a solution of 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β-hydroxy-7β,10β-di(2,2,2-trichloroethoxycarbonyloxy)-13α-[(2R,3S)-3-(4-fluorophenyl)-2-hydroxy-3-t-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (6.42 g, 5.46 mmol) dissolved in methanol (200 ml) and acetic acid (50 ml). An outer bath was heated to 60 °C, and the mixture was stirred for 30 minutes. Zinc powder was removed from the reaction mixture by filtration, and the filtrate was concentrated. The residue was dissolved in ethyl acetate and washed with a 1 % HCl aqueous solution, a saturated aqueous sodium hydrogen carbonate solution and brine. After the organic layer was dried over anhydrous sodium sulfate, the solvent was removed. The residue obtained was purified by silica gel flash column chromatography (ethyl acetate/hexane = 3/2) to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-(4-fluorophenyl)-2-hydroxy-3-t-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (2.61 g, yield: 58 %). m.p.: 159 °C (slowly decomposed) IR (nujol) ν max (cm -1 ) : 3440, 1710, 1460 FAB-MS (m/z): 826 (MH + ) 1 H-NMR (300MHz, CDCl 3 ) δ: 1.13 (3H, s), 1.24 (3H, s), 1.34 (9H, s), 1.73 (1H, s, D 2 O exchange), 1.75 (1H, d-like, D 2 O exchange), 1.76 (3H, s), 1.83 (1H, m), 1.86 (3H, d, J=1Hz), 2.29 (2H, m), 2.36 (3H, s), 2.58 (1H, m), 3.49 (1H, d, J=5Hz, D 2 O exchange), 3.92 (1H, d, J=7Hz), 4.19 (1H, d, J=8Hz), 4.22 (1H, m), 4.23 (1H, d, J=2Hz, D 2 O exchange), 4.32 (1H, d, J=8Hz), 4.58 (1H, m), 4.94 (1H, m), 5.21 (1H, d, J=2Hz), 5.25 (1H, br), 5.43 (1H, br, D 2 O exchange), 5.68 (1H, d, J=7Hz), 6.24 (1H, m), 7.08 (2H, m), 7.38 (2H, m), 7.49 (2H, m), 7.61 (1H, m), 8.10 (2H, m) Example 5 (1) While cooling by an ice-acetone bath, a solution of 262 mg of di-tert-butyl bicarbonate dissolved in 5 ml of tetrahydrofuran was added dropwise to a mixture of 663 mg of 4α-acetoxy-13α-[(2R,3S)-3-amino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one·formate, 151 mg of sodium hydrogen carbonate and 15 ml of tetrahydrofuran, and then the mixture was stirred at room temperature for 18 hours. Insolubles were removed by filtration, the filtrate was concentrated under reduced pressure, and then the residue was dissolved in ethyl acetate. After the ethyl acetate layer was washed with water and brine, and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 2 : 1) to obtain 523 mg of 4α-acetoxy-13α-[(2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one. The physical property values were coincident with those of Compound 7a of "Tetrahedron", Vol. 45, p. 4177 (1989). (2) ((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetic acid (185 mg), 129 mg of N,N'-dicyclohexylcarbodiimide and 5 mg of 4-dimethylaminopyridine were added to a solution of 505 mg of 4α-acetoxy-13α-[(2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one dissolved in 20 ml of tetrahydrofuran, and the mixture was stirred at room temperature for 4 hours. Precipitates were removed by filtration, the filtrate was concentrated under reduced pressure, and the residue was dissolved in ethyl acetate. After the ethyl acetate layer was washed with water and brine, and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 2 : 1) to obtain 434 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one. IR (nujol) ν max (cm -1 ) : 3360, 1760, 1730 FAB-MS (m/z): 1491 (MH + ) (3) Zinc (1 g) was added to a solution of 412 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)-acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one dissolved in methanol-acetic acid (12 ml-3 ml), and the mixture was stirred at 60 °C for 30 minutes. After the reaction mixture was cooled, zinc was removed by filtration. After the filtrate was concentrated under reduced pressure, the residue was dissolved in ethyl acetate. After the ethyl acetate layer was washed with a 1 % aqueous HCl solution, a saturated aqueous sodium hydrogen carbonate solution and brine, and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 1 : 2) to obtain 220 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[(3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxyacetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one. m.p.: 130 to 134 °C FAB-MS (m/z): 1143 (MH + ) IR (nujol) ν max (cm -1 ) : 3400, 1720 1 H-NMR (CDCl 3 ) δ: 1.12 (3H, s), 1.21 (3H, s), 1.24 (3H, t, J=7Hz), 1.34 (9H, s), 1.58 (1H, m), 1.64 (1H, s), 1.75 (3H, s), 1.85 (1H, m), 1.92 (3H, s), 2.15 (1H, m), 2.25 (1H, m), 2.35 (3H, s), 2.59 (1H, m), 2.92 (1H, dd, J=5, 17Hz), 3.11 (1H, dd, J=4, 17Hz), 3.90 (1H, d, J=7Hz), 4.15 to 4.25 (5H, m), 4.30 (1H, d, J=8Hz), 4.57 to 4.70 (3H, m), 4.95 (1H, m), 5.12 (2H, s), 5.19 (1H, s), 5.45 to 5.55 (3H, m), 5.67 (1H, d, J=7.0Hz),5.91 (1H, br), 6.20 (1H, m), 7.28 to 7.42 (10H, m), 7.50 (2H, m), 7.62 (1H, m), 8.10 (2H, m) Example 6 (1) Zinc (11.12 g) was added to a solution of 5.63 g of 4α-acetoxy-13α-[(2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one dissolved in methanol-acetic acid (220 ml-50 ml), and the mixture was stirred at 60 °C for 1.5 hours. After the reaction mixture was cooled, zinc was removed by filtration. The filtrate was concentrated under reduced pressure, and the residue was dissolved in ethyl acetate. After the ethyl acetate layer was washed with a 1 % aqueous HCl solution, a saturated aqueous sodium hydrogen carbonate solution and brine, and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 1 : 1 to 1 : 2) and then crystallized from hexane to obtain 2.86 g of 4α-acetoxy-13α-[(2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one. The physical property values were coincident with those of Compound 10a of "Tetrahedron", Vol. 45, p. 4177 (1989). (2) Under argon atmosphere, a solution of 328 mg of ((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)-acetic acid dissolved in 3 ml of tetrahydrofuran was cooled by an ice-acetone bath. To the solution were added 123 mg of isopropyl chloroformate and 94 mg of triethylamine, and the mixture was stirred at 0 °C or lower for 30 minutes. To the reaction mixture was added dropwise a solution of 150 mg of 4α-acetoxy-13α-[(2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one dissolved in 3 ml of tetrahydrofuran, and the mixture was stirred at 0 °C or lower for 4 hours. To the reaction mixture was added a saturated aqueous sodium hydrogen carbonate solution, and extracted with ethyl acetate. After the organic layer was washed with water and brine, and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 2 : 3) to obtain 167 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one. The physical property values were the same as described in Example 5-(3). Examples 7 to 31 By processing corresponding starting compounds in the same manner as in Example 5 or 6, the compounds shown in Tables 1 to 11 were obtained (in the tables, C 6 H 5 represents phenyl group). Example 32 0.15 g of 10 % palladium-carbon (containing 50 % of water) and 14 µl of methanesulfonic acid were added to a solution of 205 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one dissolved in 15 ml of tetrahydrofuran, and the mixture was stirred under atmospheric pressure of hydrogen for 2 hours. The catalyst was removed by filtration, the filtrate was concentrated under reduced pressure, and diethyl ether was added to the residue. Crystals precipitated were collected by filtration, washed with a diethyl ether-ethyl acetate mixed solution and then diethyl ether and dried to obtain 172 mg of 4α-acetoxy-13α-{(2R,3S)-3-tert-butoxycarbonylamino-2-[((3S)-3-amino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one·methanesulfonate. Solubility: 5 mg/ml (physiological saline) m.p.: 165 to 170 °C (decomposed) FAB-MS (m/z): 1009 (MH + ) IR (nujol)ν max (cm -1 ) : 3400, 1750, 1720 1 H-NMR (DMSO-d 6 ) δ: 0.98 (6H, s), 1.23 (3H, t, J=7.1Hz), 1.38 (9H, s), 1.51 (3H, s), 1.69 (3H, s), 2.20 to 2.34 (4H, m), 2.22 (3H, s), 2.30 (3H, s), 3.01 (1H, dd, J=5.5, 17.6Hz), 3.09 (1H, dd, J=5.5, 17.6Hz), 3.62 (1H, d, J=7.0Hz), 3.97 to 4.07 (3H, m), 4.17 to 4.28 (3H, m), 4.40 (1H, d, J=5.5Hz), 4.43 (1H, d, J=7.8Hz), 4.78 to 5.13 (6H, m), 5.17 (1H, d, J=7.4Hz), 5.40 (1H, d, J=7.0Hz), 5.79 (1H, t, J=10Hz), 7.18 (1H, br t), 7.35 to 7.44 (5H, m), 7.64 to 7.75 (2H, m), 7.90 (1H, d, J=8.6Hz), 7.99 (2H, d, J=7.1Hz), 8.44 (3H, br s) Examples 33 to 57 By processing corresponding starting compounds in the same manner as in Example 32, the compounds shown in Tables 12 to 20 were obtained. In the tables, solubility means a solubility in physiological saline. Example No. Physical properties 52 Solubility: 1 mg/ml m.p.: not lower than 157 °C (decomposed) FAB-MS (m/z): 1045 (MH + ) IR (nujol)ν max (cm -1 ): 3420, 1760, 1720 1 H-NMR (DMSO-d 6 ) δ: 1.01 (3H, s), 1.03 (3H, s), 1.21 (3H, t, J=7Hz), 1.36 (9H, s), 1.53 (3H, s), 1.67 (1H, m), 1.74 (3H, s), 1.94 (1H, m), 2.08 (1H, m), 2.27 (1H, m), 2.23 (3H, s), 2.31 (3H, s), 3.01 (1H, dd, J=5, 17Hz), 3.09 (1H, dd, J=5, 17Hz), 3.69 (1H, d, J=7Hz), 4.04 (3H, m), 4.20 (2H, q, J=7Hz), 4.39 (1H, m), 4.64 (1H, s), 4.79 (1H, d, J=16Hz), 4.90 (1H, d, J=16Hz), 4.92 (1H, d, J=9Hz), 4.98 (1H, br s), 5.02 (1H, br), 5.11 (1H, s), 5.16 (1H, d, J=6Hz), 5.45 (1H, d, J=7Hz), 5.53 (1H, dd, J=6, 10Hz), 5.89 (1H, m), 7.22 (1H, m), 7.28 (1H, m), 7.60 (2H, m), 7.70 (2H, m), 8.00 (3H, m), 8.44 (3H, br s) 54 m.p.: 161.5 to 164.5 °C (decomposed) FAB-MS (m/z): 1027 (MH + ) IR (nujol) ν max (cm -1 ): 3440 to 3400, 1750, 1710 1 H-NMR (400MHz, DMSO-d 6 ) δ: 1.02 (6H, s), 1.25 (3H, t, J=7Hz), 1.39 (9H, s), 1.55 (3H, s), 1.69 (2H, m), 1.73 (3H, s), 1.95 (1H, m), 2.3 (1H, m), 2.27 (3H, s), 2.33 (3H, s), 3.03 (1H, dd, J=6, 18Hz), 3.11 (1H, dd, J=5, 18Hz), 3.68 (1H, d, J=7Hz), 4.05 (3H, m), 4.24 (2H, m), 4.42 (1H, m), 4.52 (1H, s), 4.8 to 5.0 (5H, m), 5.11 (1H, s), 5.17 (1H, m), 5.24 (1H, d, J=2Hz), 5.45 (1H, d, J=7Hz), 5.86 (1H, m), 7.26 (2H, m), 7.45 (2H, m), 7.91 (1H, d, J=10Hz), 7.62 (2H, m), 7.73 (1H, m), 8.00 (2H, m), 8.43 (3H, br s) 56 Solubility: 15 mg/ml m.p.: 173 to 176 °C (decomposed) FAB-MS (m/z): 1039 (M+H) IR (nujol)ν max (cm -1 ): 3400, 1750, 1710 1 H-NMR (DMSO-d 6 ) δ: 1.00 (6H, s), 1.09, 1.22 (each, 3H, t, J=7.0Hz), 1.36 (9H, s), 1.52 (3H, s), 1.6 to 1.8 (2H, m), 1.71 (3H, s), 1.9 to 2.0 (1H, m), 2.2 to 2.3 (1H, m), 2.28 (3H, s), 2.31 (2H, s), 3.01 (1H, dd, J= 5.5, 17.7Hz), 3.09 (1H, dd, J=5.5, 17.7Hz), 3.50 (3H, s), 3.67 (1H, d, J=7.1Hz), 4.0 to 4.1 (3H, m), 4.22, 4.23 (each, 2H, q, J=7.0Hz), 4.39 (1H, br s), 4.40 (1H, t, J=5.5Hz), 4.81 (1H, d, J=16.5Hz), 4.91 (1H, d, J= 16.5Hz), 4.92 (1H, d, J=9Hz), 5.00 (1H, m), 5.09 (1H, s), 5.11 (1H, m), 5.16 (1H, d, J=6.7Hz), 5.43 (1H, d, J=7.1Hz), 5.80 (1H, m), 6.9 to 8.0 (10H, m), 8.43 (3H, br s) 57 Solubility: 5 mg/ml m.p.: not lower than 157 °C (decomposed) FAB-MS (m/z): 1075 (MH + ) IR (nujol)ν max (cm -1 ): 3400, 1760, 1720 1 H-NMR (DMSO-d 6 ) δ: 1.01 (3H, s), 1.03 (3H, s), 1.36 (9H, s), 1.53 (3H, s), 1.67 (1H, m), 1.74 (3H, s), 1.94 (1H, m), 2.09 (1H, m), 2.23 (3H, s), 2.27 (1H, m), 2.30 (3H, s), 3.00 (1H, dd, J=6, 17Hz), 3.08 (1H, dd, J=6, 17Hz), 3.25 (3H, s), 3.55 (2H, m), 3.69 (1H, d, J=7Hz), 4.04 (3H, m), 4.28 (2H, m), 4.43 (1H, m), 4.64 (1H, s), 4.78 (1H, d, J=16Hz), 4.90 (1H, d, J=16Hz), 4.96 (1H, m), 5.01 (2H, m), 5.11 (1H, s), 5.16 (1H, d, J=6Hz), 5.54 (1H, d, J=7Hz), 5.54 (1H, m), 5.89 (1H, m), 7.22 (1H, m), 7.28 (1H, m), 7.60 (2H, m), 7.70 (2H, m), 8.00 (3H, m), 8.45 (3H, br s) Example 58 186 mg of (3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxyacetic acid and 127 mg of N,N'-dicyclohexylcarbodiimide were added to a solution of 0.15 g of taxol (= 4α,10β-diacetoxy-13α-[(2R,3S)-3-benzoylamino-2-hydroxy-3-phenylpropionyloxy]-2α-benzoyloxy-5β,20-epoxy-1β,7β-dihydroxytax-11-en-9-one) dissolved in 8 ml of dichloromethane, and the mixture was stirred at room temperature for 26 hours. Insolubles were removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate : dichloromethane = 2 : 4 : 1) to obtain 209 mg of 4α,10β-diacetoxy-13α-{(2R,3S)-3-benzoylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β-dihydroxytax-11-en-9-one. FAB-MS (m/z): 1189 (MH + ) IR (nujol)ν max (cm -1 ): 3320, 1750, 1720 1 H-NMR (CDCl 3 ) δ: 1.11 (3H, s), 1.20 (3H, s), 1.25 (3H, t, J=7Hz), 1.59 (1H, s), 1.68 (3H, s), 1.71 (1H, s), 1.91 (3H, s), 1.93 to 2.05 (1H, m), 2.1 to 2.2 (1H, m), 2.23 (3H, s), 2.3 to 2.4 (1H, m), 2.43 (3H, s), 2.56 (1H, m), 2.90 (1H, m), 3.10 (1H, m), 3.80 (1H, d, J=7Hz), 4.10 (1H, m), 4.12 (2H, q, J=7Hz), 4.25 (2H, ABq, J=9Hz), 4.45 (1H, m), 4.62 (1H, d, J=16Hz), 4.67 (1H, d, J=16Hz), 4.97 (1H, d, J=8Hz), 5.0 to 5.1 (1H, m), 5.04 (2H, s), 5.64 (1H, d, J=3.5Hz), 5.68 (1H, d, J=7.0Hz), 5.90 (1H, t, J=8Hz), 6.05 (1H, dd, J=3.5, 8Hz), 6.25 (1H, t, J=8Hz), 6.30 (1H, s), 7.2 to 7.6 (16H, m), 7.75 (2H, d, J=7Hz), 8.15 (2H, d, J=7Hz) Example 59 195 mg of 4α,10β-diacetoxy-13α-{(2R,3S)-3-benzoylamino-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2α-benzoyloxy-5β,20-epoxy-1β,7β-dihydroxytax-11-en-9-one was processed in the same manner as in Example 32 to obtain 4α,10β-diacetoxy-13α-{(2R,3S)-3-benzoylamino-2-[((3S)-3-amino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-phenylpropionyloxy}-2a-benzoyloxy-5β,20-epoxy-1β,7β-dihydroxytax-11-en-9-one· methanesulfonate. Solubility: 0.3 mg/ml (physiological saline) m.p.: 113 to 115 °C (decomposed) FAB-MS (m/z): 1055 (MH + ) 1 H-NMR (DMSO-d 6 ) δ: 0.99 (3H, s), 1.02 (3H, s), 1.21 (3H, t, J=7Hz), 1.59 (3H, s), 1.77 (3H, s), 1.59 to 1.79 (2H, m), 2.1 to 2.31 (2H, m), 2.11 (3H, s), 2.20 (3H, s), 2.30 (3H, s), 2.9 to 3.1 (2H, m), 3.55 (1H, d, J=7Hz), 3.9 to 4.4 (6H, m), 4.82 to 4.86 (4H, m), 5.32 (1H, m), 5.40 (1H, d, J=7Hz), 5.50 to 5.56 (1H, m), 5.8 (1H, m), 6.28 (1H, s), 7.2 to 8.0 (15H, m), 8.43 (3H, br s), 9.26 (1H, d, J=8.5Hz) Example 60 (1) Under argon atmosphere, a solution of (3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetic acid (972 mg, 2.75 mmol) dissolved in tetrahydrofuran (10 ml) was cooled to -10 °C. To the solution were added triethylamine (278 mg, 2.75 mmol) and isopropyl chlorocarbonate (337 mg, 2.75 mmol), and the mixture was stirred for 30 minutes. To the mixture was added dropwise a solution of 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-(4-fluorophenyl)-2-hydroxy-3-tert-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (454 mg, 0.55 mmol) dissolved in tetrahydrofuran (10 ml), and the mixture was further stirred for 7 hours. After a saturated aqueous sodium hydrogen carbonate solution (20 ml) was added to the reaction mixture, the mixture was extracted with ethyl acetate. The organic layer was washed with water and brine and dried over anhydrous sodium sulfate. The solvent was removed, and the residue obtained was purified by silica gel flash column chromatography (ethyl acetate/hexane = 2/1) to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-(4-fluorophenyl)-2-[((3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-tert-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (544 mg, yield: 85 %). The physical property values were the same as those of the compound obtained in Example 28. (2) Methanesulfonic acid (32 µl, 0.49 mmol) and palladiumcarbon (Pd-C) (250 mg) were added to a solution of 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-(4-fluorophenyl)-2-[(3S)-3-benzyloxycarbonylamino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-tert-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one (520 mg, 0.448 mmol) dissolved in tetrahydrofuran (50 ml). The mixture was stirred under the atmospheric pressure at room temperature for 1 hour. After the catalyst was removed from the reaction mixture by filtration, the filtrate was concentrated. Diethyl ether was added to the concentrate, and the mixture was stirred for 30 minutes while cooling by an ice bath. Precipitates were collected by filtration using a glass filter and sufficiently washed with diethyl ether. The precipitates were dried under reduced pressure to obtain 4α-acetoxy-2α-benzoyloxy-5β-20-epoxy-1β,7β,10β-trihydroxy-13α-[(2R,3S)-3-(4-fluorophenyl)-2-[((3S)-3-amino-3-ethoxycarbonylpropionyloxy)acetoxy]-3-tert-butoxycarbonylaminopropionyloxy]-tax-11-ene-9-one·methanesulfonate (404 mg, yield: 80 %). The physical property values were the same as those of the compound obtained in Example 54. Reference example 1 (1) 78 mg of 1,4-bis(9-O-dihydroquinidyl)phthalazine was added to a solution of 9.88 g of potassium ferricyanide and 4.14 g of potassium carbonate dissolved in 100 ml of tert-butanol-water (1 : 1), and the mixture was stirred at room temperature for 30 minutes. The reaction mixture was adjusted to about pH 11 by adding phosphoric acid thereto. 0.05 ml of osmium tetraoxide (0.4M toluene solution) was added to the mixture, and the resulting mixture was stirred at room temperature for 30 minutes. After the mixture was cooled with ice bath, 1.98 g of methyl (2',4'-difluoro)-cinnamate was added thereto, and the mixture was stirred at room temperature overnight. After the mixture was cooled with ice bath, to the reaction mixture was added 15 g of sodium sulfite, and then, the mixture was stirred at room temperature for 30 minutes. Thereafter, ethyl acetate was added to the mixture, and the organic layer was collected by separation. The solvent was removed under reduced pressure, and the residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 1 : 1) and further recrystallized from dichloromethane-hexane to obtain 1.73 g of methyl (2S,3R)-3-(2,4-difluorophenyl)-2,3-dihydroxypropionate. [α] 20 / D = -10.0° (c = 1, chloroform) IR (nujol) ν max (cm -1 ) : 3440, 3360, 1750 MS (m/z): 232 (M + ) 1 H-NMR (CDCl 3 ) δ: 2.89 (1H, d, J=7.3Hz), 3.22 (1H, d, J=5.9Hz), 3.85 (3H, s), 4.35 (1H, dd, J=3.0, 5.9 Hz), 5.29 (1H, dd, J=3.0, 7.3Hz), 6.81 (1H, m), 6.92 (1H, m), 7.52 (1H, m) (2) Under argon atmosphere, a solution of 955 mg of methyl (2S,3R)-3-(2,4-difluorophenyl)-2,3-dihydroxypropionate dissolved in 30 ml of dichloromethane was cooled to 0 °C, and to the solution was added 940 mg of p-toluenesulfonyl chloride and 624 mg of triethylamine. After the mixture was stirred at 0 °C for 3 days, the reaction mixture was washed with water and dried, and the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 2 : 1) to obtain 1.15 g of methyl (2S,3R)-3-(2,4-difluorophenyl)-3-hydroxy-2-(p-toluenesulfonyloxy)propionate. IR (nujol) ν max (cm -1 ) : 3500, 1745 FAB-MS (m/z): 409 (M + +Na) 1 H-NMR (CDCl 3 ) δ: 2.43 (3H, s), 2.75 (1H, d, J=7Hz), 3.76 (3H, s), 5.00 (1H, d, J=3Hz), 5.41 (1H, dd, J=3, 7Hz), 6.57 (1H, m), 6.79 (1H, m), 7.20 (2H, m), 7.37 (1H, m), 7.53 (2H, m) (3) 0.26 ml of water and 1.20 g of potassium carbonate were added to a solution of 1.12 g of methyl (2S,3R)-3-(2,4-difluorophenyl)-3-hydroxy-2-(p-toluenesulfonyloxy)-propionate dissolved in 15 ml of dimethylformamide, and the mixture was stirred at room temperature overnight. Ethyl acetate and ice water were added to the reaction mixture, and the organic layer was collected by separation. After the organic layer was washed with water and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 10 : 1) to obtain 502 mg of methyl (2R,3R)-3-(2,4-difluorophenyl)-2-epoxypropionate. IR (nujol) ν max (cm -1 ) : 1760, 1740 FAB-MS (m/z): 237 (M + +Na) 1 H-NMR (CDCl 3 ) δ: 3.60 (3H, s), 3.87 (1H, dd, J=4.4Hz), 4.36 (1H, d, J=4.4Hz), 6.80 (1H, m), 6.88 (1H, m), 7.48 (1H, m) (4) Under argon atmosphere, 1 ml of methyl formate and 360 mg of sodium azide were added to a solution of 237 mg of methyl (2R,3R)-3-(2,4-difluorophenyl)-2-epoxypropionate dissolved in 9 ml of methanol-water (8 : 1), and the mixture was stirred at 50 °C for 43 hours. After the reaction mixture was cooled, ethyl acetate and ice water were added to the reaction mixture, and the organic layer was collected by separation. After the organic layer was washed with water and dried, the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 5 : 1) to obtain 274 mg of methyl (2R,3S)-3-(2,4-difluorophenyl)-3-azido-2-hydroxypropionate. IR (nujol) ν max (cm -1 ) : 3480, 2120, 1750 FAB-MS (m/z): 258 (MH + ) 1 H-NMR (CDCl 3 ) δ: 3.15 (1H, d, J=6.7Hz), 3.89 (3H, s), 4.38 (1H, dd, J=2.7, 6.7Hz), 5.22 (1H, d, J=2.7Hz), 6.87 (1H, m), 6.96 (1H, m), 7.65 (1H, m) (5) 529 mg of di-tert-butyl bicarbonate and 200 mg of 10 % palladium-carbon were added to a solution of 519 mg of methyl (2R,3S)-3-(2,4-difluorophenyl)-3-azido-2-hydroxypropionate dissolved in 20 ml of ethyl acetate, and the mixture was stirred under hydrogen atmosphere (1 atmospheric pressure) at room temperature for 9 hours. The catalyst was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 4 : 1) to obtain 594 mg of methyl (2R,3S)-3-(2,4-difluorophenyl)-3-tert-butoxycarbonylamino-2-hydroxypropionate. [α] 20 / D = -13.59° (c = 1, chloroform) IR (nujol) ν max (cm -1 ) : 3500, 3380, 1740, 1680 FAB-MS (m/z): 332 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.41 (9H, s), 3.16 (1H, d, J=4.2Hz), 3.86 (3H, s), 4.42 (1H, br), 5.39 (1H, br), 5.48 (1H, br), 6.8 to 6.9 (2H, m), 7.33 (1H, m) (6) 0.3 ml of isopropenyl methyl ether and 39 mg of pyridinium p-toluenesulfonate were added to a solution of 515 mg of methyl (2R,3S)-3-(2,4-difluorophenyl)-3-tert-butoxycarbonylamino-2-hydroxypropionate dissolved in 30 ml of benzene, and the mixture was stirred at room temperature for 30 minutes. The mixture was further stirred at 90 °C for 30 minutes and then returned to room temperature. 0.3 ml of isopropenyl methyl ether was added to the mixture, and the resulting mixture was stirred at 90 °C for 30 minutes. The mixture was cooled again to room temperature, 0.15 ml of isopropenyl methyl ether was added thereto, and the mixture was stirred at 90 °C for 4 hours. The reaction mixture was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (solvent; toluene : ethyl acetate = 50 : 1) to obtain 428 mg of methyl (4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)-5-oxazolidinecarboxylate. IR (nujol) ν max (cm -1 ) : 1760, 1740, 1700 FAB-MS (m/z): 394 (M + +Na) 1 H-NMR (CDCl 3 ) δ: 1.19 (9H, br s), 1.69 (3H, s), 1.76 (3H, s), 3.80 (3H, s), 4.47 (1H, d, J=6Hz), 5.36 (1H, br), 6.82 (1H, m), 6.90 (1H, m), 7.30 (1H, m) (7) Under ice cooling, a solution of 31 mg of lithium hydroxide dissolved in 5 ml of water was added dropwise to a solution of 402 mg of methyl (4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)-5-oxazolidinecarboxylate dissolved in 10 ml of methanol. After the mixture was stirred at room temperature for 45 minutes, the reaction mixture was concentrated under reduced pressure. Water and diethyl ether were added to the residue, and the aqueous layer was collected by separation. The aqueous layer was adjusted to about pH 2 by adding 10 % aqueous hydrochloric acid thereto under ice cooling and then extracted with chloroform. After the chloroform layer was washed with water and dried, the solvent was removed to obtain 385 mg of (4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)-5-oxazolidinecarboxylic acid. IR (neat) ν max (cm -1 ) : 3200 to 2980, 1740, 1700, 1680 FAB-MS (m/z): 380 (M + +Na) 1 H-NMR (CDCl 3 ) δ: 1.21 (9H, br s), 1.72 (3H, s), 1.78 (3H, s), 4.53 (1H, d, J=5.9Hz), 4.7 (1H, br), 5.37 (1H, br), 6.82 (1H, m), 6.91 (1H, m), 7.31 1H, m) Reference example 2 In the same manner as in Reference example 1, the carboxylic acid compounds described in Table 23 shown below were obtained. Reference example 3 (1) A solution of 0.36 g of (4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)-5-oxazolidinecarboxylic acid, 0.572 g of 4α-acetoxy-2α-benzoyloxy-5β,20-epoxy-1β,13α-dihydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one, 0.211 g of N,N-dicyclohexylcarbodiimide and 0.039 g of 4-dimethylaminopyridine dissolved in 20 ml of toluene was stirred under argon atmosphere at 80 °C for 2.5 hours. After the reaction mixture was cooled, precipitates were removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 4 : 1) to obtain 0.721 g of 4α-acetoxy-2α-benzoyloxy-13α-[4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)oxazolidin-5-ylcarbonyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one. FAB-MS (m/z): 1234 (MH + +2) (2) A solution of 0.694 g of 4α-acetoxy-2α-benzoyloxy-13α-[4S,5R)-3-tert-butoxycarbonyl-2,2-dimethyl-4-(2,4-difluorophenyl)oxazolidin-5-ylcarbonyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one dissolved in 15 ml of formic acid was stirred at room temperature for 18 hours. Formic acid was removed, and small amount of ethanol and diisopropyl ether were added to the residue. Precipitate was collected by filtration and dried to obtain 0.526 g of 4α-acetoxy-2α-benzoyloxy-13α-[(2R,3S)-3-amino-3-(2,4-difluorophenyl)-2-hydroxypropionyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one·formate. FAB-MS (m/z): 1094 (MH + +2) (3) 0.116 g of sodium hydrogen carbonate was added to a solution of 0.526 g of 4α-acetoxy-2α-benzoyloxy-13α-[(2R,3S)-3-amino-3-(2,4-difluorophenyl)-2-hydroxypropionyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one-formate dissolved in 12 ml of tetrahydrofuran, and then a solution of 0.201 g of di-tert-butyl bicarbonate dissolved in 3 ml of tetrahydrofuran was added dropwise to the mixture under ice cooling. Then, the resulting mixture was stirred at room temperature for 18 hours. Insolubles were removed by filtration, the filtrate was concentrated under reduced pressure, and the residue was dissolved in ethyl acetate. After the ethyl acetate layer was washed with water and dried, the solvent is removed. The residue was purified by silica gel column chromatography (solvent; toluene : ethyl acetate = 5 : 1) to obtain 0.288 g of 4α-acetoxy-2α-benzoyloxy-13α-[2R,3S)-3-tert-butoxycarbonylamino-3-(2,4-difluorophenyl)-2-hydroxypropionyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis-(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one. FAB-MS (m/z): 1194 (MH + +2) (4) 0.71 g of zinc powder was added to a solution of 0.26 g of 4α-acetoxy-2α-benzoyloxy-13α-[2R,3S)-3-tert-butoxycarbonylamino-3-(2,4-difluorophenyl)-2-hydroxypropionyloxy]-5β,20-epoxy-1β-hydroxy-7β,10β-bis(2,2,2-trichloroethoxycarbonyloxy)tax-11-en-9-one dissolved in methanol-acetic acid (12 ml-3 ml), and the mixture was heated to 60 °C and stirred for 90 minutes. After the mixture was cooled, zinc was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate, washed with a 1 % HCl aqueous solution, a saturated aqueous sodium hydrogen carbonate solution and brine and dried, and then the solvent was removed. The residue was purified by silica gel column chromatography (solvent; hexane : ethyl acetate = 2 : 3) to obtain 0.091 g of 4α-acetoxy-2α-benzoyloxy-13α-[2R,3S)-3-tert-butoxycarbonylamino-3-(2,4-difluorophenyl)-2-hydroxypropionyloxy]-5β,20-epoxy-1β,7β,10β-trihydroxytax-11-en-9-one. IR (nujol) ν max (cm -1 ) : 3440, 1720, 1460, 1380, 1270, 1250, 1110 FAB-MS (m/z): 844 (MH + ) 1 H-NMR (CDCl 3 ) δ: 1.13 (3H, s), 1.26 (3H, s), 1.31 (9H, s), 1.60 (1H, s), 1.73 (1H, s), 1.76 (3H, s), 1.85 (1H, m), 1.93 (3H, s), 2.2 to 2.4 (2H, m), 2.43 (3H, s), 2.59 (1H, m), 3.38 (1H, br), 3.93 (1H, d, J=7Hz), 4.20 (1H, d, J=8Hz), 4.22 (2H, m), 4.33 (1H, d, J=8Hz),4.56 (1H, br), 4.96 (1H, d-like), 5.21 (1H, s), 5.39 (1H, d-like), 5.53 (1H, br d), 5.69 (1H, d, J=7Hz), 6.29 (1H, t-like), 6.87 (1H, m), 6.93 (1H, m), 7.38 (1H, m), 7.50 (2H, t-like), 7.60 (1H, t-like), 8.12 (2H, d, J=7Hz) Reference example 4 (1) In the same manner as in Reference example 3-(1), the compounds in Table 24 shown below were obtained from corresponding starting compounds. (2) In the same manner as in Reference example 3-(2), the compounds in Table 25 shown below were obtained from corresponding starting compounds. (3) In the same manner as in Reference example 3-(3), the compounds in Table 26 shown below were obtained from corresponding starting compounds. (4) In the same manner as in Reference example 3-(4), the compounds in Table 27 shown below were obtained from corresponding starting compounds. The process of the present invention is different from either of the methods which have been reported, i.e., the method in which a reaction time is long and N-benzoyl-3-phenylisoserine having protected hydroxyl group and giving a low yield is used (the above method (A)); the method using an azetidinone compound or an oxazolidine compound synthesis of which is complicated (the above methods (B) and (C)); and the method using osmium oxidation having no regioselectivity and giving a low yield (the above method (D)). The feature of the process of the present invention resides in that the 13α-(3-amino-2-hydroxypropionyloxy)-baccatin derivative (VI) can be prepared efficiently by quantitatively introducing an epoxypropionyl group in which 3-position is substituted by an aryl group or the like into hydroxyl group at 13-position of the baccatin compound (II); cleaving and halogenating an oxirane ring of the resulting compound regioselectively and stereoselectively; and then substituting an azido group by a halogen atom regioselectively and stereoselectively; and then reducing an azido group. The 13α-(3-amino-2-hydroxypropionyloxy)baccatin derivative (VI) obtained as described above is a synthetic intermediate of taxol, N-debenzoyl-N-(t-butoxycarbonyl)-10-deacetyltaxol or the like which is useful as an antitumor agent. By using the process described in the present specification, the taxol derivative (X) can be prepared efficiently. Further, the 13α-(epoxypropionyloxy)baccatin compound (III), the 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound (IV) and a 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound (V) which are generated in the course of the process of the present invention are novel compounds and have important significance in asymmetric synthesis of the taxol, N-debenzoyl-N-(t-butoxycarbonyl)-10-deacetyltaxol or the like which is efficiently prepared by the present invention.

Claims: A process for preparing a 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VI): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl), or a salt thereof, which comprises introducing an azido group to a 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein A represents a halogen atom; and R 1 , R 2 , R 3, R 4 and X have the same meanings as defined above, and reducing the resulting 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound represented by the formula (V): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above, and, if necessary, converting the resulting compound to a salt thereof. The process of claim 1, wherein said compound represented by the formula (IV) is prepared by halogenating a 13α-epoxypropionyloxybaccatin compound represented by the formula (III): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined in claim 1. The process of claim 2, wherein said compound represented by the formula (III) is prepared by condensing a baccatin compound represented by the formula (II): wherein R 1 , R 2 , R 3 , and R 4 have the same meanings as defined in claim 2, and an epoxypropionic acid compound represented by the formula (I): wherein X has the same meaning as defined in claim 2, or a reactive-derivative thereof. A process for preparing a 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound represented by the formula (V): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl), which comprises introducing an azido group to a 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein A represents a halogen atom; and R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above, which is prepared by halogenating a 13α-epoxypropionyloxybaccatin compound represented by the formula (III): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above. The process of claim 4, wherein said compound represented by the formula (III) is prepared by condensing a baccatin compound represented by the formula (II): wherein R 1 , R 2 , R 3 and R 4 have the same meanings as defined in claim 4, and an epoxypropionic acid compound represented by the formula (I): wherein X has the same meaning as defined in claim 4, or a reactive derivative thereof. A process for preparing a 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group, a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl); and A represents a halogen atom which comprises halogenating a 13α-epoxypropionyloxy-baccatin compound represented by the formula (III): wherein R 1 , R 2 , R 3 , R 4 and X have the same meanings as defined above, which is prepared by condensing a baccatin compound represented by the formula (II): wherein R 1 , R 2 , R 3 and R 4 have the same meanings as defined above, and an epoxypropionic acid compound represented by the formula (I): wherein X has the same meaning as defined above or a reactive derivative thereof. The process of any one of the preceding claims wherein R 1 is a C 2-7 alkanoyl group, a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 2 is a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 3 is a C 2-7 alkanoyl group; R 4 is benzoyl group; and X is a phenyl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, or C 1-5 alkenyl group. The process of claim 7, wherein R 1 is trichloroethoxycarbonyl group, R 2 is trichloroethoxycarbonyl group, R 3 is acetyl group, R 4 is benzoyl group, X is phenyl group and A is bromine atom. A process for preparing a taxol compound represented by the formula (IX): wherein R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, R 5 represents a C 2-7 alkoxycarbonyl group which may be substituted by 1 to 3 groups selected from the group consisting of a halogen atom and a C 1-5 alkoxy group (where said C 2-7 alkoxycarbonyl group may have a 3- to 5-membered cycloalkyl portion), a C 2-7 alkanoyl group which may be substituted by a halogen atom, an arylcarbonyl group which may be substituted by 1 or 2 C 1-5 alkoxy groups or an aromatic heterocyclic group-substituted carbonyl group; R 11 represents a C 2-7 alkanoyl group or hydrogen atom; and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl), which comprises reacting a 13α-(3-amino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VI): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 , R 4 and X have the same meanings as defined above or a salt thereof which is obtained by the process in any one of the claims 1 to 3 with a compound represented by the formula (VII): R 5 OH wherein R 5 has the same meaning as defined above, a salt thereof or a reactive derivative thereof, and removing a protective group from the resulting 13α-(3-acylamino-2-hydroxypropionyloxy)baccatin compound represented by the formula (VIII): wherein R 1 , R 2 , R 3 , R 4 , R 5 and X have the same meanings as described above. A 13α-epoxypropionyloxybaccatin compound represented by the formula (III): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl) A 13α-(3-halogeno-2-hydroxypropionyloxy)baccatin compound represented by the formula (IV): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom; X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl); and A represents a halogen atom. A 13α-(3-azido-2-hydroxypropionyloxy)baccatin compound represented by the formula (V): wherein R 1 represents a C 2-7 alkanoyl group or a protective group for hydroxy group; R 2 represents a protective group for hydroxy group; R 3 represents a C 2-7 alkanoyl group; R 4 represents a benzoyl group which may be substituted by a C 1-5 alkyl group, C 1-5 alkoxy group or a halogen atom, and X represents an aryl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, a C 1-5 alkenyl group, or a C 1-5 alkynyl group (wherein aryl represents a group selected from phenyl, naphthyl, furyl, thienyl and pyridyl). The compound of claim 10, wherein R 1 is a C 2-7 alkanoyl group, a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 2 is a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 3 is a C 2-7 alkanoyl group; R 4 is benzoyl group; and X is a phenyl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, or a C 1-5 alkenyl group. The compound of claim 13, wherein R 1 is trichloroethoxycarbonyl group; R 2 is trichloroethoxycarbonyl group; R 3 is acetyl group; R 4 is benzoyl group; and X is phenyl group. The compound of claim 11, wherein R 1 is a C 2-7 alkanoyl group, a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 2 is a trihalo-C 2-7 alkoxycarbonyl group or a tri-C- 1-5 alkylsilyl group; R 3 is a C 2-7 alkanoyl group; R 4 is benzoyl group; and X is a phenyl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, or a C 1-5 alkenyl group. The compound of claim 15, wherein R 1 is trichloroethoxycarbonyl group; R 2 is trichloroethoxycarbonyl group; R 3 is acetyl group; R 4 is benzoyl group; X is phenyl group and A is bromine atom. The compound of claim 12, wherein R 1 is a C 2-7 alkanoyl group, a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 2 is a trihalo-C 2-7 alkoxycarbonyl group or a tri-C 1-5 alkylsilyl group; R 3 is a C 2-7 alkanoyl group; R 4 is benzoyl group; and X is a phenyl group which may be substituted by 1 or 2 groups selected from the group consisting of a halogen atom, a C 1-5 alkyl group and a C 1-5 alkoxy group, or a C 1-5 alkenyl group. The compound of claim 17, wherein R 1 is trichloroethoxycarbonyl group; R 2 is trichloroethoxycarbonyl group; R 3 is acetyl group; R 4 is benzoyl group; and X is phenyl group.

Inventors: HARADA NAOYUKI, HASHIYAMA TOMIKI, NAKANISHI NORIYUKI, OHASHI MOTOAKI, OZAKI KUNIHIKO, TSUJIHARA KENJI, YAMAGUCHI TETSUO C O TANABE SE, HARADA, NAOYUKI, HASHIYAMA, TOMIKI, NAKANISHI, NORIYUKI, OHASHI, MOTOAKI, OZAKI, KUNIHIKO, TSUJIHARA, KENJI, YAMAGUCHI, TETSUO, C/O TANABE SEIYAKU KASHIMA-RYO
Applicants: TANABE SEIYAKU CO, TANABE SEIYAKU CO., LTD.
Application year: 1995
Main classification: C07D305
IPC codes: C07D407, C07D305, C07D409