Addition reactions of heterocyclic compounds. Part XXX. Acetylenedicarboxylic esters with benzopyridines possessing activated methyl groups

Abstract

Dimethyl and diethyl acetylenedicarboxylate, with 2-methylquinoline and some derivatives, 1-methylisoquinoline, and 6-methylphenanthridine, give dihydroazepines with the migration of an ester group; benzoquinolizines and other products are also formed. The n.m.r. spectra of the ethoxycarbonyldihydroazepines and some derivatives have been fully analysed. Hydrogenation, protonation, bromination, hydrolysis, and oxidation of the azepines have been investigated, and a scheme for their formation is proposed. The n.m.r. spectra for some benzoquinolizines are tabulated.