Stereoselective allylation of 2-formyl amides or 3-oxo amides has been studied. Treatment of 2-formyl-N, N-dimethylpropanamide (1a) with allylzinc bromide gave 3-hydroxy-2, N, N- trimethyl-5-pentenamide as a stereoisomeric mixture (2a: 3a= 63: 37). Meantime, the reaction of 1a with allyltrimethylsilane in the presence of Lewis acid such as EtAlCl 2 or BF 3· OEt 2 afforded threo-adduct 2a exclusively. Whereas treatment of 2-benzoyl-N, N- ...
