Phase-transfer catalysed reaction of N-(benzylidene)benzylamine with arylmethyleneanilines afforded the stereoisomeric 1,2,4,5-tetraarylimidazolidines 3 and 4; a two-step addition–cyclisation mechanism was suggested on the basis of NMR analysis of the isolated products and the observed epimerisation of the prepared imidazolidines.
