Studies on Heteropentalenes. II. Cycloaddition of Imidazo[2,1-<i>b</i>]thiazoles, Thiazolo[3,2-<i>a</i>]benzimidazole, and Imidazo[2,1-<i>b</i>]benzothiazole with a Reactive Acetylenic Ester
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
2,3-Dibenzoylpyrrolo[2,1-b]benzothiazole (2) and 6,7-dibenzoylpyrrolo[2,1-b]thiazoles (5a–b) have been synthesized by utilizing the cycloaddition reactions of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]thiazoles, respectively, with dibenzoylacetylene followed by the elimination of a nitrile from each of the cycloadducts. Heteroannelations to 2 and 5 have been achieved by their reactions with hydrazine
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
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]benzoth
先前提出的结构,噻唑并[3,2-a][1,5]苯二氮卓和[1,4]二氮杂[7,1-b]苯并噻唑衍生物,噻唑并[3,2-a]苯并咪唑反应的环加合物和咪唑并[2,1-b]苯并噻唑衍生物与丙炔酸酯,被修改为甲基2-[4-甲基-(E)-1H-[1,4]噻嗪并[4,3-a]苯并咪唑-1-亚基)甲氧基羰基甲基]-(E)-丙烯酸甲酯和[2-甲基-(E)-10H-咪唑并[2,1-c][1,4]苯并噻嗪-10-亚基)-甲氧基羰基甲基]-(E)-丙烯酸甲酯,分别通过 X 射线结构分析推导出其结构。