Heteroarene-fused benzodiazepines. Part 1. Synthesis of thieno-[2,3-b][1,5]-, -[3,2-b][1,5]-, and -[3,4-b][1,5]-benzodiazepinones

Abstract

The synthesis of the 4H-thieno-[2,3-b][1,5]-, -[3,2-b][1,5]-, and -[3,4-b][1,5]-benzodiazepinone ring systems is described. Sodium methylsulphinylmethanide was used for the intramolecular cyclisation of the intermediate amino-esters (5), (9), and (14). However, attempted cyclisation of ethyl 2-(2-amino-4-fluoroanilino)-5-ethyl-thiophen-3-carboxylate (5b) with sodium hydride at a higher temperature caused rearrangement to a benzimidazolone (12).