To obtain the subject optically pure compound useful for asymmetric synthesis as a ligand for asymmetric catalysts by utilizing a unique reactivity of phosphine borane.
This phosphine compound which is either of enantiomers of formula V is obtained by reacting a dichlorophenylphosphine of the structural formula, Ph-P-Cl2 (Ph is phenyl) with a Grignard reagent of formula I (X is a halogen), preferably, at -50 to -80°C, then, reacting the resultant product with (-)-menthol in the presence of a base, further, reacting the reaction product with a borane-tetrahydrofuran complex to make a mixture of diastereomers of formula II, reacting the mixture with a lithium compound of the structural formula, CH3-Li to obtain either of enantiomers of formula III, reacting the resultant product with an alkyllithium of the formula, R-Li (R is a lower alkyl) in the presence of a copper chloride to obtain either of enantiomers of formula IV and then reacting the resultant compound with a base.
OSHIKI TOSHIYUKI
ONOZAWA TAKASHI
TOGO HIDEO
YOKOYAMA MASATAKA
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