Allenes and acetylens—XXIII1: Synthesis of α-allenic amines via allenic imines obtained from organocopper reactions

N-2,3-alkadienyldiphenylmethanimines 5a-h are formed in moderate yields in 1,3-substitution reactions (S_N2′) of propargylic sulfonates with an organocopper reagent derived from metalated N-methyldiphenylmethanimine 1 and Me₂S·CuBr. The imines can be readily hydrolyzed to primary α-allenic amines. Alkylation of the imines with methyl fluorosulfonate followed by hydrolysis gives N-methyl-subsituted secondary α-allenic amines.