Addition reactions of heterocyclic compounds. Part LIX. A 13C tracer study of the mechanism of formation of azepines from 2-methyl-quinolines and dimethyl acetylenedicarboxylate

Abstract

A ¹³C label in the methyl group of 2-methylquinoline and its 6-bromo-derivative was found at position 10 or 11 of the azepino[1,2-a]quinolines formed in reactions with dimethyl acetylenedicarboxylate. This excludes a reaction pathway involving an ester shift but is consistent with the possibility of a spiro intermediate.