Chemoselective synthesis of 1,2-disubstituted benzimidazoles in lactic acid without additive
作者:Zhi-Yu Yu、Jia Zhou、Qiu-Sheng Fang、Ling Chen、Zhi-Bin Song
DOI:10.1515/chempap-2016-0056
日期:2016.1.1
Lactic acid is recognised as a biocompatible medium for the chemoselective synthesis of the 1,2-disubstituted benzimidazole scaffold via a direct one-potcyclocondensation of o-phenylenediamine with aldehydes. Various 1,2-disubstituted benzimidazole derivatives were successfully synthesised with high selectivity with good to excellent yields without any additional catalyst or additive. Most products
o-phenylenediamine and carbonyl compounds by Brønstedacid/base assisted titanocene dichloride. Mechanism research including NMR and ESI-MS analyses and control experiments elucidated the new catalytic species formed by Cp2TiCl2 and the combination of titanocene Lewis acid with Brønstedacid/base was responsible for selective transformations of aldehyde and ketone with o-phenylenediamine into benzimidazole