al j chem soc a 2334 1971 of the starting optically active phosphine compounds l 1 the optically active compound of formula iii i e 2 2 39 bis diphenylphosphinyl 5 5 39 6 6 39 7 7 39 8 8 39 octahydro 1 1 39 binaphthyl hereinafter abbreviated as och binap can be synthesized for example as follows 2 2 39 dibromo 1 1 39 binaphthyl synthesized by the process disclosed in h takaya et al j orc chem vol 51 p 629 1986 is hydrogenated in the presence of a ruthenium on carbon catalyst to obtain 2 2 39 dibromo 5 5 39 6 6 39 7 7 39 8 8 39 octahydro 1 1 39 binaphthyl 2 2 39 dibromo 1 1 39 bitetrahydronaphthalene which is then reacted with metallic magnesium to form a grignard reagent the resulting grignard reagent is condensed with diphenylphosphinyl chloride to synthesize racemic och binap the racemate is optically resolved by recrystallization from a mixed solvent of chloroform and ethyl acetate in the presence of optically active dibenzoyltartaric acid as a resolving agent and the precipitated crystal collected by filtration is treated with 1n sodium hydroxide to obtain a phosphine oxide the optical purity of the phosphine oxide is determined by high performance liquid chromatography using an optically active column and the above recrystallization operation is repeated until the product becomes optically.