Potassium Hydroxide/Dimethyl Sulfoxide Promoted Intramolecular Cyclization for the Synthesis of Benzimidazol-2-ones
摘要:
A new protocol for intramolecular N-arylations of ureas to form benzimidazol-2-ones has been developed. The cyclization reaction occurs In the presence of KOH and DMSO at close to ambient temperature. Under these conditions the yields are high and a wide range of functional groups are tolerated.
Unsymmetrical N,N'-diarylureas may be alkylated regioselectively at the more sterically congested nitrogen atom. The resulting mono-N-alkylated ureas undergo directed metalation (ortholithiation) with sec-BuLi to yield, on electrophilic quench, products functionalized regioselectively at the ring bearing the alkylated nitrogen atom.
Slow interconversion of enantiomeric conformers or atropisomers of anilide and urea derivatives of 2-substituted anilines
N-Acylated 2-substituted anilines undergo slow Ar-N bond rotation, allowing in some cases isolation of enantiomeric or diastereoisomeric atropisomers and in others the determination of the rate of Ar-N bond rotation by NMR. 2-Iodoanilides bearing a branched N-substituent demonstrate sufficient enantiomeric stability to be resolvable, either by HPLC or by formation of diastereoisomeric lactanilide derivatives
Potassium Hydroxide/Dimethyl Sulfoxide Promoted Intramolecular Cyclization for the Synthesis of Benzimidazol-2-ones
作者:Astrid Beyer、Christine M. M. Reucher、Carsten Bolm
DOI:10.1021/ol2008878
日期:2011.6.3
A new protocol for intramolecular N-arylations of ureas to form benzimidazol-2-ones has been developed. The cyclization reaction occurs In the presence of KOH and DMSO at close to ambient temperature. Under these conditions the yields are high and a wide range of functional groups are tolerated.