Cyclisation of N-prop-2-ynylbenzylamines : preparation of a 1,2-dihydroisoquinoline and a 2-benzazepine

Abstract

N-Prop-2-ynylbenzylamines undergo acid-catalysed ring-closure to form heterocyclic bases. The results of two cyclisations are reported. With a terminal acetylene group, the product was a 1,2-dihydroisoquinoline. In contrast, with a phenyl-substituted acetylene the reaction gave a 2-benzazepine. Mass spectra have been obtained for both products, and a reaction mechanism is postulated.