Thioalkenylphosphonic acid ester and process for the preparation thereof

Abstract: A phosphonic acid ester compound of the formula: wherein R 1 represents a monovalent group selected from hydrogen, alkyl, cycloalkyl, cycloalkenyl, aryl, aralkyl, alkenyl and silyl, R 2 and R 3 each represent aryl and R 4 represents alkylene or cycloalkylene. The ester compound is produced by reaction of an acetylene compound, R 1 C≡CH or HC≡C-R 4 -C≡CH, with with a phosphorothioate, (R 2 O) 2 P(=O)SR 3 , in the presence of a palladium complex catalyst.

Description: BACKGROUND OF THE INVENTION This invention relates to a thioalkenyl phosphonic acid ester and to a process for the preparation thereof. Thioalkenyl phosphonic esters are a group of compounds useful as intermediate compounds for the production of fine chemicals, because they can easily give, by Michael reaction with a nucleophile, a carbanion which in turn causes Horner-Emmons addition reaction with a carbonyl compound and because they can undergo a carbon-carbon bond-forming reaction by regio- or stereoselective coupling with a vinyl halide, an aryl halide or Grignard reagent in the presence of a transitional metal catalyst. At present, no methods have been known which can produce thioalkenyl phosphonic esters by a single stage reaction of a hydrocarbon. A reaction of a thioalkenyl halogen compound with a secondary phosphite under basic conditions may yield a thioalkenyl phosphonic ester. An addition of a secondary phosphite to a thioalkyne may also produce a thioalkenyl ether. These methods, however, are not advantageous from the industrial point of view, because the sulfur-containing raw materials are not easily obtainable. SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a simple process which can produce a thioalkenyl phosphonic ester at low costs using an easily feasible starting material. Another object of the present invention is to provide a novel thioalkenyl phosphonic ester. In accordance with one aspect of the present invention, there is provided a process for the preparation of a thioalkenylphosphonic acid ester of the following formula (I): R 1 C(SR 3 )=CHP(=O) (OR 2 ) 2 wherein R 1 stands for a monovalent group selected from hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, an alkenyl group and a silyl group, R 2 stands for an aryl group and R 3 stands for an aryl group, comprising reacting an acetylene compound of the following formula (II): R 1 C≡CH wherein R 1 is as defined above, with a phosphorothioate of the following formula (III): (R 2 O) 2 P(=O)SR 3 wherein R 2 and R 3 are as defined above, in the presence of a palladium complex catalyst. In another aspect, the present invention provides a process for the preparation of a bis(thioalkenyl)phosphonic acid ester of the following formula (IV): [P(=O) (OR 2 ) 2 ]CH=C(SR 3 )-R 4 -C(SR 3 )=CH[P(=O) (OR 2 ) 2 ] wherein R 2 stands for an aryl group, R 3 stands for an aryl group and R 4 stands for an alkylene group or a cycloalkylene group, comprising reacting an acetylene compound of the following formula (II): HC≡C-R 4 -C≡CH wherein R 4 is as defined above, with a phosphorothioate of the following formula (III): (R 2 O) 2 P(=O)SR 3 wherein R 2 and R 3 are as defined above, in the presence of a palladium complex catalyst. The present invention also provides a thioalkenylphosphonic acid ester of the following formula (I): R 1 C(SR 3 )=CHP(=O) (OR 2 ) 2 wherein R 1 stands for a monovalent group selected from hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, an alkenyl group and a silyl group and R 2 stands for an aryl group and R 3 stands for an aryl group. The present invention further provides a bis(thioalkenyl)phosphonic acid ester of the following formula (IV): (P(=O) (OR 2 ) 2 ]CH=C(SR 3 )-R 4 -C(SR 3 )=CH[P(=O) (OR 2 ) 2 ] wherein R 2 stands for an aryl group, R 3 stands for an aryl group and R 4 stands for an alkylene group or a cycloalkylene group. Other objects, features and advantages of the present invention will become apparent from the detailed description of the preferred embodiments of the invention to follow. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The phosphorothioate used as a raw material in the process of the present invention is represented by the formula (III): (R 2 O) 2 P(=O)SR 3 wherein R 2 and R 3 each stand for an aryl group preferably having 6-14 carbon atoms, more preferably 6-12 carbon atoms. Illustrative of suitable aryl groups are phenyl, tolyl and napththyl. The phosphorothioate is reacted with an acetylene compound of the formula (II) or (V) R 1 C≡CH HC≡C-R 4 -C≡CH wherein R 1 stands for a monovalent group selected from (a) hydrogen atom, (b) an alkyl group preferably having 1-18 carbon atoms, more preferably 1-10 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl octyl or decyl, (c) a cycloalkyl group preferably having 5-18 carbon atoms, more preferably 5-10 carbon atoms, such as cyclohexyl, cyclooctyl or cyclododecyl, (d) a cycloalkenyl group preferably having 5-18 carbon atoms, more preferably 5-10 carbon atoms, such as cyclohexenyl, cyclooctenyl or cyclododecenyl, (e) an aryl group preferably having 6-14 carbon atoms, more preferably 6-10 carbon atoms, such as phenyl, naphthyl, substituted phenyl (e.g. tolyl or benzylphenyl) or substituted naphthyl (e.g. methylnaphthyl), (f) an aralkyl group preferably having 7-13 carbon atoms, more preferably 7-9 carbon atoms, such as benzyl, phenethyl, phenylbenzyl, naphthylethyl or naphthylmethyl, (g) an alkenyl group preferably having 2-18 carbon atoms, more preferably 2-10 carbon atoms, such as vinyl, propenyl or 3-butenyl and (h) a silyl group which may have 1-3 substituents such as a hydrocarbyl group having 1-18 carbon atoms, preferably 1-8 carbon atoms, such as an alkyl (e.g. methyl, ethyl, propyl, butyl or octyl), cycloalkyl (e.g. cyclohexyl), aryl (e.g. phenyl, tolyl, naphthyl) or aralkyl (e.g. benzyl, phenethyl or naphthylmethyl), and R 4 stands for (i) an alkylene group preferably having 1-20 carbon atoms, more preferably 1-10 carbon atoms, such as methylene or tetramethylene, or (j) a cycloalkylene group preferably having 5-18 carbon atoms, more preferably 5-10 carbon atoms, such as cyclopentylene or cyclohexylene. Illustrative of suitable acetylene compounds are non-substituted acetylene, butyne, octyne, phenylacetylene, trimethylsilylacetylene, 1,8-nonadiyne, diethynylbenzene, hexynenitrile and cyclohexenylacetylene. It is without saying that the present invention is not limited to these acetylene compounds. The above reaction is performed in the presence of a palladium complex catalyst. Any known palladium complex catalyst may be used. Low valency palladium complexes, inclusive of zero-valent complexes, may be suitably used. Low valency palladium complexes having a tertiary phosphine or a tertiary phosphite as a ligand are especially suitably used. In this case, a precursor substance which can form in situ a low valency palladium complex having a tertiary phosphine or a tertiary phosphite as a ligand during the reaction of the acetylene compound with the secondary phosphite may also be suitably used. For example, a palladium complex containing neither tertiary phosphine nor tertiary phosphite may be used in conjunction with a tertiary phosphine or a tertiary phosphite so that a low valency palladium complex having a tertiary phosphine or a tertiary phosphite as a ligand is formed in the reaction mixture. Further, a palladium complex containing a tertiary phosphine or tertiary phosphite may be used in conjunction with another tertiary phosphine or another tertiary phosphite. A tertiary phosphine of the following formula may be suitably used as a ligand of the palladium complex catalyst: wherein R 5 , R 6 and R 7 are each (k) an alkyl group preferably having 1-18 carbon atoms, more preferably 1-12 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl octyl or decyl, (l) a cycloalkyl group preferably having 4-6 carbon atoms, more preferably 5-6 carbon atoms, such as cyclopentyl or cyclohexyl, (m) an aryl group preferably having 6-14 carbon atoms, more preferably 6-10 carbon atoms, such as phenyl, naphthyl, substituted phenyl (e.g. tolyl or benzylphenyl) or substituted naphthyl (e.g. methylnaphthyl), or (n) an aralkyl group preferably having 6-13 carbon atoms, more preferably 6-10 carbon atoms, such as benzyl, phenethyl, phenylbenzyl or naphthylmethyl. Examples of the tertiary phosphines include triphenylphosphine, tris(4-chlorophenyl)phosphine, tris(4-fluorophenyl)phosphine, tritolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, diphenylcyclohexylphosphine and phenyldicyclohexylphosphine. Illustrative of suitable palladium complex catalysts containing a tertiary phosphine are tetrakis(triphenylphosphine)palladium, tris(triphenylphosphine)palladium, and ethylenebis-(triphenylphosphine)palladium. A tertiary phosphite of the following formula may be suitably used as a ligand of the palladium complex catalyst: wherein R 5 , R 6 and R 7 are as defined above. Examples of the tertiary phosphites include trimethylphosphite and triphenylphosphite. Palladium complex catalysts containing other ligands than tertiary phosphine or tertiary phosphite, such as bis(dibenzylideneacetone)palladium or palladium acetate, may also used, preferably in conjunction with the palladium complex catalyst containing tertiary phosphine or phosphite, for the purpose of the present invention. The palladium complex catalyst is used in a catalytically effective amount and, generally, in an amount of up to 20 mole %, based on the acetylene compound. The acetylene compound and the phosphorothioate are generally used in a stoichiometric amount. However, the use of the acetylene compound or the phosphorothioate in a stoichiometrically excess amount does not adversely affect the desired reaction. The reaction may be carried out with or without using a solvent. The solvent, when used, may be a hydrocarbon solvent or an ether solvent. The reaction is generally performed from room temperature to about 300° C, preferably 50-150° C. It is preferred that the reaction be carried out in an oxygen-free atmosphere, such as in the atmosphere of nitrogen, argon or methane. After the termination of the reaction, the product can be separated by any known manner such as chromatography, distillation and recrystallization. The following examples will further illustrate the present invention. The symbol Ph represents a phenyl group, t-Bu represents a t-butyl group, Me represents a methyl group and n-Bu represent a n-butyl group. Example 1 To 2 ml of toluene were added 2 mmol of 1-octyne, 2 mmol of PhSP(O)(OPh) 2 and 2 mol % of Pd(PPh 3 ) 4 (tetrakis(triphenylphosphine)palladium) and the mixture was reacted at 100° C for 5 hours in the atmosphere of nitrogen. The reaction mixture was concentrated and separated by liquid chromatography to isolate diphenyl (Z)-2-phenylthio-1-octenylphosphonate with a yield of 92 %. The physical properties of the novel product are given below. 1 H-NMR (CDCl 3 ) : δ7.15-7.41 (m, 15H), 5.81 (d, 1H J H-P = 17.3 Hz), 2.12 (t, 2H, J = 7.6 Hz), 1.32-1.60 (m, 2H), 1.12-1.24 (m, 2H), 1.04-1.09 (m, 4H), 0.80 (t, 3H, J = 7.0 Hz); 13 C- NMR (CDCl 3 ) : δ165.3, 150.6 (J C-P = 8.3 Hz), 134.7, 130.9, 129.6, 129.2, 129.1, 124.9, 120.7 (J C-P = 4.1 Hz), 110.6 (J C-P = 197.6 Hz), 38.2 (J C-P = 19.7 Hz), 31.3, 28.5, 28.2, 22.4, 14.0 31 P-NMR (CDCl 3 ): δ8.3 IR (liquid film): 2932, 2860, 2593, 1491, 1272, 1216, 1193, 1164, 1071, 1025, 930, 754 cm -1 Elementary analysis (as C 26 H 29 O 3 PS): calculated C, 69.00; H, 6.46 measured C, 69.06; H, 6.72 HRMS (EI, 70eV) calculated 452.1575 measured 452.1577 Examples 2-15 Example 1 was repeated in the same manner as described except that the acetylene compounds shown below were each used in lieu of 1-octyne to produce novel thioalkenylphosphonic acid esters shown below. The yield and physical properties of the esters are summarized below. Example 2 Acetylene compound: Product: Yield: 65 % 1 H-NMR (CDCl 3 ) : δ7.09-7.42 (m, 15H), 6.57 (d, 1H, J H-P = 17.6 Hz), 1.14 (s, 9H); 31 P-NMR (CDCl 3 ) : δ6.8 IR (liquid film): 2972, 1591, 1491, 1276, 1214, 1191, 1164, 1027, 926, 748 cm -1 Elementary analysis (as C 24 H 25 O 3 PS): calculated C, 67.91; H, 5.94 measured C, 68.21; H, 6.14 HRMS (EI, 70eV) calculated 424.1262 measured 424.1172 Product of Example 3 Acetylene compound: Product: Yield: 90 % 1 H-NMR (CDCl 3 ) : δ7.14-7.36 (m, 30H), 5.74 (d, 2H, J H-P = 17.4 Hz), 2.00 (t, 4H, J = 7.0 Hz), 1.13-1.19 (m, 4H), 0.79-0.83 (m, 2H); 31 P-NMR (CDCl 3 ) : δ8.1 IR (liquid film): 2938, 1591, 1491, 1270, 1191, 1164, 1025, 928, 754 cm -1 Elementary analysis (as C 45 H 42 O 6 P 2 S 2 ): calculated C, 67.15; H, 5.26 measured C, 67.39; H, 5.41 FAB-MASS (EI, 70eV): 804 (M+) Product of Example 4 Acetylene compound: Product: Yield: 87 % % (96/4) 1 H-NMR (CDCl 3 ) : δ6.97-7.41 (m, 20H), 6.12 (d, 1H, J H-P = 17.6 Hz); 31 P-NMR (CDCl 3 ) : δ7.3 IR (liquid film): 3062, 2928, 1593, 1555, 1,491, 1441, 1274, 1191, 1027, 926, 758, 690 cm -1 Elementary analysis (as C 26 H 21 O 3 PS): calculated C, 70.26; H, 4.76 measured C, 70.29; H, 4.94 HRMS (EI, 70eV) calculated 444.0949 measured 444.0902 Product of Example 5 Acetylene compound: Product: Yield: 71 % (93/7) 1 H-NMR (C 6 D 6 ) : δ7.08-7.33 (m, 19H), 6.19 (d, 1H, J H-P =17.0 Hz); 31 P-NMR (CDCl 3 ) : δ6.8 IR (liquid film): 3,064, 1593, 1489, 1272, 1212, 1191, 1164, 1093, 1025, 938, 768 cm -1 Elementary analysis (as C 26 H 20 ClO 3 PS): calculated C, 65.20; H, 4.21 measured C, 64.90; H, 4.27 HRMS (EI, 70eV) calculated 478.0559 measured 478.0489 Product of Example 6 Acetylene compound: Product: Yield: 69 % (91/9) 1 H-NMR (CDCl 3 ) : 86.83-7.34 (m, 19H), 6.16 (d, 1H, J H-P = 17.0 Hz); 31 P-NMR (CDCl 3 ) : δ7.1 IR (liquid film): 3066, 1597, 1491, 1274, 1212, 1191, 1162, 1025, 934, 797, 766 cm -1 Elementary analysis (as C 26 H 20 FO 3 PS): calculated C, 67.52; H, 4.36 measured C, 67.51; H, 4.40 HRMS (EI, 70eV): calculated 462.0855 measured 462.0799 Product of Example 7 Acetylene compound: Product: Yield: 89 % (98/2) 1 H-NMR (CDCl 3 ) : δ6.97-7.33 (m, 19H), 6.20 (d, 1H, J H-P = 17.9 Hz), 2.22 (s, 3H); 31 P-NMR (CDCl 3 ) : δ7.6 IR (liquid film): 3062, 1593, 1551, 1491, 1274, 1212, 1191, 1164, 1025, 932, 766 cm -1 Elementary analysis (as C 27 H 23 O 3 PS): calculated C, 70.73; H, 5.06 measured C, 70.65; H, 5.07 HRMS (EI, 70eV): calculated 458.1106 measured 458.1096 Product of Example 8 Acetylene compound: Product: Yield: 84 % 1 H-NMR (CDCl 3 ) : δ7.06-7.50 (m, 15H), 5.88 (d, 1H, J H-P = 16.4 Hz), 2.30 (t, 2H, J = 7.0 Hz), 2.04 (t, 2H, J = 7.3 Hz), 1.63-1.69 (m, 2H); 31 P-NMR (CDCl 3 ) : δ6.9 IR (liquid film): 2928, 1591, 1491, 1270, 1191, 1164, 1025, 928, 754 cm -1 Elementary analysis (as C 24 H 22 NO 3 PS): calculated C, 66.19; H, 5.09; N, 3.22 measured C, 66.32; H, 5.16; N, 3.14 HRMS (EI, 70eV): calculated 435.1058 measured 435.1035 Product of Example 9 Acetylene compound: Product: Yield: 89 % 1 H-NMR (CDCl 3 ) : δ7.15-7.46 (m, 15H), 5.94 (d, 1H J H-P = 17.4 Hz), 3.55-3.68 (m, 2H), 2.39 (t, 2H, J = 6.5 Hz), 1.82 (bs, 1H) ; 31 P-NMR (CDCl 3 ) : δ7.4 IR (liquid film): 3416, 3062, 2932, 1591, 1491, 1249, 1212, 1191, 936, 754 cm -1 Elementary analysis (as C 22 H 21 O 4 PS) : calculated C, 64.07; H, 5.13 measured C, 63.96; H, 5.16 HRMS (EI, 70eV) calculated 412.0898 measured 412.0902 Product of Example 10 Acetylene compound: Product: Yield: 85 % 1 H-NMR (CDCl 3 ) : δ7.17-7.39 (m, 15H) , 5.90 (d, 1H J H-P = 16.7 Hz), 3.26 (t, 2H, J = 6.7 Hz), 2.33 (t, 2H, J = 7.0 Hz), 1.77-1.79 (m, 2H); 31 P-NMR (CDCl 3 ): δ7.6 IR (liquid film): 2962, 1591, 1491, 1270, 1214, 1191, 1025, 930, 752 cm -1 Elementary analysis (as C 23 H 22 ClO 3 PS): calculated C, 62.09; H, 4.98 measured C, 62.44; H, 5.06 HRMS (EI, 70eV) : calculated 444.0716 measured 444.0698 Product of Example 11 Acetylene compound: Product: Yield: 68 % 1 H-NMR (CDCl 3 ): δ7.08-7.34 (m, 15H), 5.85 (d, 1H J H-P = 16.7 Hz), 3.97 (t, 2H, J = 7.0 Hz), 2.41 (t, 2H, J = 7.0 Hz), 1.04 (s, 9H); 31 P-NMR (CDCl 3 ) : δ6.9 IR (liquid film): 2976, 1729, 1591, 1491, 1280, 1214, 1191, 1162, 932, 768 cm -1 Elementary analysis (as C 27 H 29 O 5 PS) : calculated C, 65.31; H, 5.89 measured C, 65.66; H, 6.14 HRMS (EI, 70eV) calculated 496.1473 measured 496.1425 Product of Example 12 Acetylene compound: Product: Yield: 91 % 1 H-NMR (CDCl 3 ): δ7.10-7.41 (m, 15H), 6.09 (bs, 1H), 6.04 (d, 1H, J H-P = 16.6 Hz), 1.92-1.97 (m, 4H), 1.31-1.34 (m, 4H); 31 P-NMR (CDCl 3 ): δ8.6 IR (liquid film): 3062, 2934, 1593, 1551, 1491, 1274, 1214, 1191, 1164, 1027, 928, 766 cm -1 Elementary analysis (as C 26 H 25 O 3 PS): calculated C, 69.62; H, 5.62 measured C, 69.58; H, 5.80 HRMS (EI, 70eV) calculated 448.1262 measured 448.1213 Product of Example 13 Acetylene compound: Product: Yield: 88 % 1 H-NMR (CDCl 3 ): δ7.07-7.36 (m, 15H), 6.16 (d, 1H J H-P =17.7 Hz), 3.67 (s, 2H), 3.11 (s, 3H); 31 P-NMR (CDCl 3 ): δ8.6 IR (liquid film): 3046, 2934, 1591, 1491, 1274, 1214, 1191, 1120, 930, 756 cm -1 Elementary analysis (as C 22 H 21 O 4 PS) : calculated C, 64.07; H, 5.13 measured C, 64.35; H, 5.23 HRMS (EI, 70eV) calculated 412.0898 measured 412.0839 Product of Example 14 Acetylene compound: Product: Yield: 94 % 1 H-NMR (CDCl 3 ) : δ7.15-7.38 (m, 15H), 6.54 (d, 1H J H-P = 20.1 Hz), 2.88 (s, 2H), 2.19 (t, 4H, J = 6.8 Hz), 1.14-1.15 (m, 8H), 0.82 (t, 6H, J = 6.7 Hz); 31 P-NMR (CDCl 3 ): δ10.0 IR (liquid film): 3064, 2960, 2866, 1593, 1491, 1274, 1216, 1193, 1164, 930, 768 cm -1 Elementary analysis (as C 29 H 36 NO 3 PS): calculated C. 68.34; H, 7.12; N, 2.75 measured C, 68.90; H, 7.39; N, 2.67 HRMS (EI, 70eV): calculated 509.2154 measured 509.2124 Product of Example 15 Acetylene compound: Product: Yield: 60 % 1 H-NMR (CDCl 3 ) : δ7.14-7.36 (m, 15H), 6.43 (d, 1H J H-P = 22.9 Hz), -0.08 (s, 9H); 29 Si-NMR (CDCl 3 ) : δ4.4 (J P-Si = 26.2 Hz) IR (liquid film): 3064, 2960, 1593, 1491, 1272, 1251, 1212, 1191, 1164, 930, 841, 793, 754 cm -1 Elementary analysis (as C 23 H 25 O 3 PSSi): calculated C, 62.70; H, 5.72 measured C, 63.26; H, 5.60 HRMS (EI, 70eV) calculated 440.1031 measured 440.1035

Claims: A process for the preparation of a thioalkenylphosphonic acid ester of the following formula (I): R 1 C(SR 3 )=CHP(=O) (OR 2 ) 2 wherein R 1 stands for a monovalent group selected from hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, an alkenyl group and a silyl group, R 2 stands for an aryl group and R 3 stands for an aryl group, comprising reacting an acetylene compound of the following formula (II): R 1 C≡CH wherein R 1 is as defined above, with a phosphorothioate of the following formula (III): (R 2 O) 2 P(=O)SR 3 wherein R 2 and R 3 are as defined above, in the presence of a palladium complex catalyst. A process for the preparation of a bis(thioalkenyl)phosphonic acid ester of the following formula (IV): [P(=O) (OR 2 ) 2 ]CH=C(SR 3 )-R 4 -C(SR 3 )=CH[P(=O) (OR 2 ) 2 ) wherein R 2 stands for an aryl group, R 3 stands for an aryl group and R 4 stands for an alkylene group or a cycloalkylene group, comprising reacting an acetylene compound of the following formula (II): HC≡C-R 4 -C≡CH wherein R 4 is as defined above, with a phosphorothioate of the following formula (III): (R 2 O) 2 P(=O)SR 3 wherein R 2 and R 3 are as defined above, in the presence of a palladium complex catalyst. A thioalkenylphosphonic acid ester of the following formula (I) R 1 C(SR 3 )=CHP(=O) (OR 2 ) 2 wherein R 1 stands for a monovalent group selected from hydrogen atom, an alkyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, an alkenyl group and a silyl group and R 2 stands for an aryl group and R 3 stands for an aryl group. A bis(thioalkenyl)phosphonic acid ester of the following formula (IV): [P(=O) (OR 2 ) 2 ]CH=C(SR 3 )-R 4 -C(SR 3 )=CH(P(=O) (OR 2 ) 2 ] wherein R 2 stands for an aryl group, R 3 stands for an aryl group and R 4 stands for an alkylene group or a cycloalkylene group.

Inventors: HAN LI-BIAO, TANAKA MASATO, HAN, LI-BIAO, TANAKA, MASATO, Han, Li-Biao, Nat. Inst. for Mat. and Chem. Res., Tanaka, Masato, Nat. Inst. for Mat. and Chem. Res.
Applicants: NAT INST OF ADVANCED IND SCIEN, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
Application year: 2000
Main classification: C07F9
IPC codes: C07B61, C07F9, B01J31