Studies on Heteropentalenes. II. : Cycloaddition of Imidazo[2,1-b]thiazoles,Thiazolo[3,2-a]benzimidazole, and Imidazo[2,1-b]benzothiazole with a Reactive Acetylenic Ester

Creators Abe Noritaka

Creators Nishiwaki Tarozaemon

Creators Komoto Noriko

Cycloaddition of imidazo[2,1-b]thiazoles with dialkyl acetylenedicarboxylate follows dual courses depending on the polarity of the solvent, affording pyrrolo[2,1-b]thiazoles in an aprotic nonpolar solvent, or imidazo[1,2-a]pyridines and imidazo[3,4-a]pyridines, together with thiophenes, in an aprotic polar solvent. Thiazolo[3,2-a]benzimidazole and imidazo[2,1-b]benzothiazole were also found to react with the acetylenedicarboxylate to give pyrido[1,2-a]benzimidazole and pyrrolo[2,1-a]benzothiazole, respectively. The reactions would be accounted for in light of the Diels-Alder reaction in an aprotic nonpolar solvent and the 1,4-dipolar cycloaddition in an aprotic polar solvent.

[ISSN]0009-2673

[NCID]AA00580132

https://doi.org/10.1246/bcsj.53.3308

[isPartOf] [URI]http://www.jstage.jst.go.jp/browse/bcsj/-char/en