Addition reactions of heterocyclic compounds. Part 69. Further studies of reactions between 2-alkylquinolines and dimethyl acetylenedicarboxylate

Abstract

Dimethyl acetylenedicarboxylate (DMAD) has been treated with ethyl quinoline-2-acetate, other quinolines with activated 2-methyl groups, and 2-acetyloxyquinoline, and the products identified spectroscopically. The mechanism of the conversion of 2-methylquinoline to tetramethyl 7a,8,9,9a-tetra hydrocyclobuta[4,5]pyrrolo[1,2-a]quinoline-7, r-7a,c-9,c-9a-tetracarboxylate, and derivatives, by DMAD has been investigated and mechanistic schemes proposed. Various reactions of this pyrroloquinoline have been re-interpreted on the basis of the new structure for this compound and ¹³C n.m.r. spectra.