Radical cyclisation onto imidazoles and benzimidazoles
摘要:
A new protocol for the synthesis of [1, 2-a]-fused benzimidazoles and imidazoles has been developed using intramolecular homolytic aromatic substitution via omega-alkyl radicals generated from 1-(omega-benzeneselenylalkyl)- 2-(benzenesulfenyl)-benzimidazoles and -2-(p-toluenesulfonyl)imidozoles. (C) 1997 Elsevier Science Ltd.
Radical cyclisation onto imidazoles and benzimidazoles
摘要:
New synthetic methodology has been developed for the synthesis of [1,2-a]Fused imidazoles and benzimidazoles using intramolecular homolytic aromatic substitution. In the intramolecular substitution, N-(omega-alkyl) radicals are generated using Bu3SnH from N-(omega-phenylselanyl)aIkyl side chains. Phenylselanyl groups are used as radical leaving groups to avoid problems in the N-alkylation of imidazoles and benzimidazoles. Arylsulfones for imidazoles, and phenylsulfides for benzimidazoles, are used as the leaving groups in the homolytic substitutions. (C) 1999 Elsevier Science Ltd. All rights reserved.