Phosphoranes (10-P-5) bearing cyanomethyl, acetamide, and N, N-dimethylacetamide groups were examined for Wittig type reactions. All three reacted to give the corresponding olefins. The reaction of the cyanomethyl reagent with aldehydes gave α, β-unsaturated cyanides with high Z-selectivity in the case of aliphatic aldehydes (Z: E= 94: 6 to 99: 1). On the other hand, the reactions of the two amide reagents with aldehydes yielded α, β- ...