R= alkyl, vinyl, Ph, or CECR'Y= Br (n= 1.0) or R (n= 0.5) M= Li or MgXaLiBr (eq 2; yield of 3 after distillation 65-8570). In Table I the applied reaction conditions and the composition of cuprates 2 are given. Attempts to realize a similar reaction with Grignard reagents under copper (1) bromide catalysis (5 mol 70 of CuBr was used) were not successful. The choice of the reaction medium for the conversion depicted in eq 2 appeared to be very important. It ...