Addition reactions of heterocyclic compounds. Part LII. Further adducts from substituted 2-methylquinolines and dimethyl acetylenedicarboxylate

Abstract

The ‘dark red’ adducts from 2-methylquinolines and dimethyl acetylenedicarboxylate have been resolved into two types and identified as hexamethyl 6,7,7a,8-tetrahydrobenzo[f]cyclopenta[a]quinolizine-6,7,7a,8,9,10-hexacarboxylates [e.g.(12)], which are readily converted into tetramethyl 5-(2-quinolyl)cyclopenta-2,4-diene-1,2,3,4-tetracarboxylates. Other products from these reactions were also identified from their n.m.r., mass, and u.v. spectra, and included benzo[c]quinolizine-, azepino[1,2-a]quinoline-, and 2-propenylquinoline-carboxylic esters; 2-(trismethoxycarbonylphenyl)quinolines were also obtained from 2,8-dimethyl- and 2,4,6,8-tetramethyl-quinoline. The formation of these products is discussed.