Scandium Pentafluorobenzoate-Catalyzed Unexpected Cascade Reaction of 2-Aminobenzaldehydes with Primary Amines: A Process for the Preparation of Ring-Fused Aminals.

An unexpected cascade reaction of 2-aminobenzaldehydes with arylamines catalyzed by scandium pentafluorobenzoate [Sc(Pfb)3] was reported as a facile strategy for the efficient synthesis of a novel class of polycyclic ring-fused aminals N-substituted-6,7,1 1b,13-tetrahydro-6,12-[1,2]benzenoquinazolino[3,4-α]- R quinazolin-13-amines 1. Under similar conditions, a series of the analogues of Tröger's base, 13-substituted-5,6,11,12-tetrahydro-6,12-epiminodibenzo[b/f] [1,5]diazodnes 2 were obtained when the arylamines were replaced by methanamines. A possible mechanism for the formation of 1 and 2 was proposed. [ABSTRACT FROM AUTHOR]