The reaction of some [1,2,3]triazolo[1,5-a]quinolinium 1,2, [1,2,3]triazolo[5,1-a] isoquinolinium 3,4 and [1,2,3]triazolo[5,1-b]thiazolium 5,6 ylides with dimethyl acetylenedicarboxylate is described. Compounds as dimethyl pyrrolo[1,2-a]quinoline-1,2-dicarboxylate 19, dimethyl pyrrolo[2, I-a]isoquinoline-2,3:dicarboxylate 20, 1,1-dicyano-2,3-dimethoxycarbonyl-1H-pyrido[1,2-a]quinoline 24, 4,4-dicyano-2,3-dimethoxycarbonyl-4H-pyrido[2,1-a]isoquinoline 25, and 7-methyl-5,6-dimethoxy-carbonylpyrrolo[2,1-a]thiazole 14b, are formed. (C) 1998 Elsevier Science Ltd. All rights reserved.