Acid-catalyzed double-cyclization reactions of N,N-dibenzylaminoacetaldehyde dialkyl acetals and related compounds : General synthesis of 7,12-dihydro-5H-6,12-methanodibenz(c,f)azocines and related compounds.

Abstract

A number of N, N-dibenzylaminoacetaldehyde diakyl acetales (1) double-cyclized in 70% perchloric acid or triflic acid (trifluoromethanesulfonic acid) to give good yields of 7, 12-dihydro-5H-6, 12-methanodibenz[c, f]azocines (2) even when a powerful electron-withdrawing substituent, for example a nitro group, was present on the benzene ring. Triflic acid treatment of α-dibenzylaminoketones (3) caused double-cyclization to give 12-substituted derivatives of 2.