Method of producing alkenylphosphine oxide or bis (alkenylphosphine oxide)

Abstract: An acetylene or diacetylene compound is reacted with a secondary phosphine oxide to produce an alkenylphosphine oxide or bis(alkenylphosphine oxide) in the presence of a palladium complex catalyst.

Description: This invention relates to a method of producing an alkenylphosphine oxide compound. An alkenylphosphine oxide compound is easily reduced to a tertiary phosphine which is widely utilized as a ligand of various catalysts. Alkenylphosphine oxide compounds easily react with nucleophiles and various radical species and, further, can be utilized for Horner-Witting reaction. Thus, alkenylphosphine oxide compounds now play important roles in synthesis of fine chemicals. One known method for the production of an alkenylphosphine oxide includes reacting an alkenyl Grignard reagent with a halogenated phosphorus compound. This method unavoidably produces a magnesium salt (See, for instance, US-A-358581). Also known is a method in which a secondary phosphine oxide is reacted with an alkenyl halide (See, for instance, Synthesis, 86, 1986, pp. 691-692). This method produces hydrogen halide which should be trapped as a salt. In DE-B-1241995 a diphenylvinylphosphine oxide is prepared by reacting chlorodiphenylphosphine with ethanol to obtain diphenylethoxyphosphine, further reacting said diphenylethoxyphosphine with 1,2-dibromoethane, and the product with a tertiary amine. The present invention has been made in view of the above problems of the conventional methods. In accordance with one aspect of the present invention there is provided a method of producing an alkenylphosphine oxide represented by the following formula (I) and/or (VIII): wherein R 1 and R 2 are independently selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group, an alkoxy group, an aryloxy group and a silyl group and R 3 represents an alkyl group, a cycloalkyl group, aralkyl group or an aryl group, said method being characterized in that an acetylene compound represented by the following formula (II) : R 1 C ≡ CR 2 wherein R 1 and R 2 are as defined above, is treated with a secondary phosphine oxide represented by the formula (III): wherein R 3 is as defined above, in the presence of a palladium complex catalyst. The groups represented by the symbols R 1 , R 2 and R 3 may contain one or more inert substituents. In another aspect, the present invention provides a method of producing a bis(alkenylphosphine oxide) represented by the following formula (V) and/or (VI): wherein R 1 and R 2 are independently selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group, an alkoxy group, an aryloxy group and a silyl group, R 3 represents an alkyl group, a cycloalkyl group, aralkyl group or an aryl group and R 5 represents a divalent group selected from an alkylene group, a cycloalkylene group, an arylene group, a heteroarylene group, an aralkylene group, alkenylene group, an alkylene dioxy group, an arylene dioxy group, an oxalkylene group and an oxalkylenearylene group, said method being characterized in that a diacetylene compound represented by the following formula (VII) : R 1 C ≡ C - R 5 - C ≡ CR 2 wherein R 1 , R 2 and R 5 are as defined above, is treated with a secondary phosphine oxide represented by the formula (III): wherein R 3 is as defined above, in the presence of a palladium complex catalyst. The groups represented by the symbol R 1 , R 2 , R 3 and R 5 may contain one or more inert substituents. The present invention will now be described in detail below. In the present invention, an acetylene compound represented by the above formula (II) or (VII) is treated with a secondary phosphine oxide represented by the above formula (III). Examples of the groups R 1 and R 2 in the formula (II) and (VII) include a hydrogen atom, a methyl group, a propyl group, a benzyl group, a phenyl group, a thienyl group, a 3-butenyl group, an ethoxy group, a phenoxy group and a trimethylsilyl group. Examples of the group R 5 include a tetramethylene group, a phenylene group, a thienylene group, a ferrocenylene group and a phenylenedioxy group. Examples of the acetylene compounds include acetylene, butyne, octyne, phenylacetylene, trimethylsilylacetylene, ethynylthiophene, diethynylbenzene, nonane-1,8-diyne, hexynonitrile, 3-butyne-1-ol and cyclohexenylacetylene. Examples of the group R 3 in the formula (III) include a methyl group, an ethyl group, a hexyl group, a cyclohexyl group, a phenyl group and a benzyl group. The reaction of the acetylene compound of the formula (II) or (VII) with the secondary phosphine oxide of the formula (III) is carried out in the presence of a palladium complex catalyst, preferably a low atomic valent palladium complex catalyst. An example of suitable palladium complex catalysts is a zero-valent palladium complex having tertiary phosphines or tertiary phosphites as ligands. Also preferred is the use of a precursor complex which is converted in situ to a zero-valent palladium complex catalyst during the reaction of the acetylene compound. Furthermore, a palladium complex having no tertiary phosphine or tertiary phosphite ligands may be used, when added to the reaction system together with a tertiary phosphine or phosphite. In this case, a low atomic valent palladium complex having tertiary phosphine or tertiary phosphite ligands is formed in situ during the reaction of the acetylene compound. Examples of tertiary phosphine or tertiary phosphite ligands include triphenylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, trimethylphosphine, triethylphosphine, diphenylcyclohexylphosphine, phenyldicyclohexylphosphine, 1,4-bis(diphenylphosphino)butane, trimethylphosphite and triphenylphosphite. Examples of palladium complexes having no tertiary phosphine or tertiary phosphite ligands and used together with a tertiary phosphine or phosphite include bis(benzylideneacetone)palladium and palladium acetate. Examples of suitable palladium complex catalysts include dimethylbis(triphenylphosphine)palladium, dimethylbis(diphenylmethylphosphine)palladium, dimethylbis(triethylphosphine)palladium, ethylenebis(triphenylphosphine)palladium, and tetrakis(triphenylphosphine)-palladium. A product obtained by reducing a divalent palladium complex, such as dichlorobis(triphenylphosphine)-palladium, with a suitable reducing agent such as butyllithium may also be used as the palladium catalyst. The palladium catalyst may be used in a so-called "catalytic amount" and, generally, in an amount of 20 mole % or less based on the amount of the acetylene compound. When the above reaction is carried out in the presence of a phosphinic acid represented by the following formula (IV): wherein R 4 represents an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, the substitution position of the phosphine oxide radical -PO(R 3 ) can be controlled. The reaction of the acetylene compound with the secondary phosphine oxide is carried out with or without using a solvent. A hydrocarbon or ether solvent can be used. The amount of the acetylene compound is not specifically limited but is generally about 1 mole per mole of the secondary phophine oxide. The reaction temperature is generally from room temperature to about 200°C, preferably 50 to 150°C. The reaction is preferably performed in an inert gas atmosphere such as nitrogen, argon or methane. The alkenylphosphine oxide compound thus obtained can be isolated from the reaction mixture by any conventional method such as chromatography, distillation or recrystallization. The following examples will further illustrate the present invention. Example 1 In 2 ml of benzene were dissolved 1 mmol of 4-octyne and 1 mmol of diphenylphosphine oxide. To this solution, 3 mol % of cis-PdMe 2 (PPh 2 Me) 2 (Me: methyl, Ph: phenyl) was added. The resulting mixture was then heated at 70°C for 36 hours in the atmosphere of nitrogen. The NMR analysis of the product revealed that 4-octenyldiphenylphosphine oxide was produced. The product was isolated by liquid chromatography with in 81 % yield. Example 2 Example 1 was repeated in the same manner as described except that diphenylacetylene was used in place of 4-octyne and that the reaction was carried out for 12 hours. (1,2-Diphenylethenyl)diphenylphosphine oxide was obtained in 94 % yield. Example 3 Example 1 was repeated in the same manner as described except that acetylene gas was used in place of 4-octyne, that cis-PdMe 2 (PPhMe 2 ) 2 was used in place of cis-PdMe 2 (PPh 2 Me) 2 and that the reaction was carried out for 5 hours. Vinyldiphenylphosphine oxide was obtained in 54 % yield. Example 4 In 2 ml of benzene were dissolved 1 mmol of 1-octyne and 1 mmol of diphenylphosphine oxide. To this solution, 5 mol % of Pd(PPh 3 ) 4 was added. The resulting mixture was then heated at 35°C for 20 hours in the atmosphere of nitrogen. The NMR analysis of the product revealed that 1-octen-1-yldiphenylphosphine oxide and 1-octen-2-yldiphenylphosphine oxide were produced in a molar ratio of 96:4. The total yield was 90 %. Example 5 In 2 ml of benzene were dissolved 1 mmol of 1-octyne and 1 mmol of diphenylphosphine oxide. To this solution, 0.04 mmol of diphenylphosphinic acid and 3 mol % of cis-PdMe 2 (PPhMe 2 ) 2 were added. The resulting mixture was then heated at 70°C for 4 hours in the atmosphere of nitrogen. The NMR analysis of the product revealed that 1-octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 95:5. The total yield was 100 %. Example 6 Example 5 was repeated in the same manner as described except that cis-PdMe 2 (PPh 2 Me) 2 was used in place of cis-PdMe 2 (PPhMe 2 ) 2 . 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 84:16. The total yield was 100 %. Example 7 Example 6 was repeated in the same manner as described except that the reaction was carried out at 45°C. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 83:17. The total yield was 15 %. Example 8 Example 6 was repeated in the same manner as described except that tetrahydrofuran was used in place of benzene and that the reaction was carried out at 67°C. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 82:18. The total yield was 97 %. Example 9 Example 5 was repeated in the same manner as described except that Pd(PPh 3 ) 4 was used in place of cis-PdMe 2 (PPhMe 2 ) 2 and that the reaction was performed for 3 hours. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 33:67. The total yield was 89 %. Example 10 Example 5 was repeated in the same manner as described except that a 1:1 mixture of cis- and trans-PdMe 2 (PMe 3 ) 2 was used in place of cis-PdMe 2 (PPhMe 2 ) 2 and that the reaction was performed for 5 hours. 1-Octen-2-yldiphenyl- phosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 93:7. The total yield was 45 %. Example 11 Example 10 was repeated in the same manner as described except that the reaction was performed for 15 hours. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 93:7. The total yield was 100 %. Example 12 Example 5 was repeated in the same manner as described except that a 1:1 mixture of cis- and trans-PdMe 2 (PEt 3 ) 2 (Et: ethyl) was used in place of cis-PdMe 2 (PPhMe 2 ) 2 and that the reaction was performed for 5 hours. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 90:10. The total yield was 100 %. Examples 13-20 Example 5 was repeated in the same manner as described except that the acetylene compounds shown in Table 1 below were used in place of 1-octyne and that the reaction was performed for 3 hours. The products and their yields thereof are summarized in Table 1. In Example 16, cis-PdMe 2 (PPh 2 Me) 2 was used as the catalyst. Example 21 Example 8 was repeated in the same manner as described except that cis-PdMe 2 (PPh 2 Me) 2 was replaced by a mixture of PdCl 2 (PPh 3 ) 2 with 2.1 mmol of methyllithium. 1-Octen-2-yldiphenylphosphine oxide was obtained in 72 % yield. Example 22 Example 5 was repeated in the same manner as described except that the amount of diphenylphosphinic acid was decreased to 0.01 mmol. 1-Octen-2-yldiphenylphosphine oxide and 1-octen-1-yldiphenylphosphine oxide were produced in a molar ratio of 70:30. Examples 23-28 Example 4 was repeated in the same manner as described except that the acetylene compounds shown in Table 2 below were used in place of 1-octyne. The products and their yields are summarized in Table 2.

Claims: A method of producing an alkenylphosphine oxide represented by the following formula (I) and/or (VIII) : wherein R 1 and R 2 are independently selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group, an alkoxy group, an aryloxy group and a silyl group and R 3 represents an alkyl group, a cycloalkyl group, aralkyl group or an aryl group, said method being characterized in that an acetylene compound represented by the following formula (II) : R 1 C ≡ CR 2 wherein R 1 and R 2 are as defined above, is treated with a secondary phosphine oxide represented by the formula (III): wherein R 3 is as defined above, in the presence of a palladium complex catalyst. A method as claimed in claim 1, wherein said reaction of said acetylene compound (II) with said secondary phosphine oxide (III) is performed in the presence of a phosphinic acid represented by the following formula (IV): wherein R 4 represents an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group. A method of producing a bis(alkenylphosphine oxide) represented by the following formula (V) and/or (VI): wherein R 1 and R 2 are independently selected from a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group, an alkoxy group, an aryloxy group and a silyl group, R 3 represents an alkyl group, a cycloalkyl group, aralkyl group or an aryl group and R 5 represents a divalent group selected from an alkylene group, a cycloalkylene group, an arylene group, a heteroarylene group, an aralkylene group, alkenylene group, an alkylene dioxy group, an arylene dioxy group, an oxalkylene group and an oxalkylenearylene group, said method being characterized in that a diacetylene compound represented by the following formula (VII) : R 1 C ≡ C - R 5 - C ≡ CR 2 wherein R 1 , R 2 and R 5 are as defined above, is treated with a secondary phosphine oxide represented by the formula (III) : wherein R 3 is as defined above, in the presence of a palladium complex catalyst. A method as claimed in claim 3, wherein said reaction of said diacetylene compound (VII) with said secondary phosphine oxide (III) is performed in the presence of a phosphinic acid represented by the following formula (IV): wherein R 4 represents an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group.

Inventors: HAN LI-BIAO, TANAKA MASATO, HAN, LI-BIAO, TANAKA, MASATO
Applicants: NAT INST OF ADVANCED IND SCIEN, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
Application year: 1997
Main classification: C07F9
IPC codes: C07F9