TRANSITION-METAL-CATALYZED SUBSTITUTION-REACTION OF ALLYLIC PHOSPHATES WITH GRIGNARD-REAGENTS

S(N)2-selective Grignard coupling with primary allylic diphenylphospha tes was successfully achieved using Ni or Fe catalyst. In sharp contra st, a catalytic amount of CuCN.2LiCl promoted a S(N)2'-selective coupl ing reaction. In the presence of the copper catalyst, stereochemically homogeneous gamma-disubstituted allyl Grignard reagents reacted at th e less substituted allylic terminus (alpha-position) with an allylic d iphenylphosphate selectively without losing the double bond geometry.