Traceless solid-phase synthesis of 5-benzoylbenzimidazoles

Abstract

A traceless linker strategy for the solid-supported synthesis of 5-benzoylbenzimidazoles has been developed. A benzyl cyanide functional group was linked to 2% divinylbenzene cross-linked polystyrene through a dimethylsilyl linker. Coupling with 5-chloro-2-nitroaniline followed by oxidative decyanation gave benzophenone 11 as a key intermediate in an efficient one-pot reaction procedure. After reduction of the nitro group and oxidative cyclization with a variety of aldehydes in the presence of DDQ, a series of polymer-supported benzimidazoles was produced. Final traceless cleavage of the arylsilane linker with TBAF provided a small library of 5-benzoylbenzimidazoles.Key words: solid-support, traceless linker, arylsilane, 5-benzoylbenzimidazole.