Revised Structures, 1-Methylene-1H-[1,4]thiazino[4,3-a]benzimidazole and 10-Methylene-10H-imidazo[2,1-c][1,4]benzothiazine Derivatives, for the Cycloadducts Accompanying Rearrangement from Imidazo[2,1-b]benzothiazole and Thiazolo[3,2-a]benzimidazole Derivatives with Propiolic Esters

Abstract

Formerly-proposed structures, thiazolo[3,2-a][1,5]benzodiazepine and [1,4]diazepino[7,1-b]benzothiazole derivatives, cycloadducts from the reactions of thiazolo[3,2-a]benzimidazole and imidazo[2,1-b]benzothiazole derivatives with propiolic esters, are revised to methyl 2-[4-methyl-(E)-1H-[1,4]thiazino[4,3-a]benzimidazol-1-ylidene)methoxycarbonylmethyl]-(E)-acrylate and methyl [2-methyl-(E)-10H-imidazo[2,1-c][1,4]benzothiazine-10-ylidene)-methoxycarbonylmethyl]-(E)-acrylate, respectively, whose structures are deduced by X-ray structure analysis.