α,α-Dibromoketones as Synthetic Equivalents of α-Bromoketones for the Synthesis of Thiazolo[3,2-a]benzimidazoles

Utilization of α,α-dihalocarbonyl compounds as synthetic equivalents to α-halocarbonyl compounds has been explored in the synthesis of a wide range of highly useful heterocycles and α- functionalized ketones. The continuously growing demand of α,α-dibromoketones, as highly reactive and mild synthetic precursors/intermediates, to carry out selective organic transformations, prompted us to investigate their potential application for the synthesis of thiazolo[3,2-a]benzimidazoles. In this study, a remarkable application of α,α-dibromoacetophenones 5a-g in the development of a facile protocol for the synthesis of thiazolo[3,2-a]benzimidazoles 4a-g by avoiding the use of lachrymatory α-haloketones is described. Although the mechanism for the debromination from the intermediate compound 6 under these conditions is not confirmed, possible pathways have been suggested.