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.
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.
作者:Steven M. Allin、William R.S. Barton、W. Russell Bowman、Emma Bridge (née Mann)、Mark R.J. Elsegood、Tom McInally、Vickie McKee
DOI:10.1016/j.tet.2008.06.014
日期:2008.8
Alkyl radicals have been cyclised onto pyrroles, imidazoles and pyrazoles, and acyl radicals cyclised onto pyrroles, using Bu3SnH-, (TMS)3SiH- and Bu3GeH-mediated aromatic homolytic substitution for the synthesis of bicyclic N-heterocycles. The reactions yield intermediate π-radicals that lose hydrogen in the rearomatisation step of the aromatic homolytic substitution. Mechanistic studies of these
One-pot double intramolecular homolytic aromatic substitution routes to dialicyclic ring fused imidazobenzimidazolequinones and preliminary analysis of anticancer activity
作者:Vincent Fagan、Sarah Bonham、Michael P. Carty、Fawaz Aldabbagh
DOI:10.1039/c003511d
日期:——
Bu3SnH/1,1′-azobis(cyclohexanecarbonitrile) (ACN)-mediated five, six, and seven-membered double alkyl radical cyclizations onto imidazo[5,4-f]benzimidazole and imidazo[4,5-f]benzimidazole are described. The quinone derivatives evaluated show selective toxicity towards human cervical (HeLa) and prostate (DU145) cancer cell lines (with negligible toxicity towards a normal human cell line, GM00637). Only the Fremy oxidation of the 6-aminoimidazo[5,4-f]benzimidazole gave iminoquinone, which showed high specificity towards the prostate cancer cell line (DU145).