Addition reactions of heterocyclic compounds. Part XLV. New azepines from substituted 2-methylquinolines and dialkyl acetylenedicarboxylates

Abstract

Tetramethyl 10,11-dihydroazepino[1,2-a]quinoline-7,8,9,10-tetracarboxylates and tetramethyl 4a-methyl-4aH-benzo[c]quinolizine-1,2,3,4-tetracarboxylates have been isolated from the reactions of a series of 3- and 4-substituted 2-methylquinolines with dimethyl acetylenedicarboxylate. Similar azepines have been obtained from 2-ethyl- and 2-benzyl-quinoline, but 2-ethyl-and 2,3-dimethyl-quinoline also give the corresponding 7,8,9,11-tetra-esters. Reaction sequences accounting for the formation of these azepines are discussed.