Carbohydrate Building Blocks in the Ugi Three-Component Coupling Reaction: Convenient Annulation of Iminosugars on Imidazoles
作者:Lal Yadav、Vijai Rai、Santosh Singh、Pankaj Singh
DOI:10.1055/s-0030-1258252
日期:2010.12
An unprecedented version of the Ugi three-component coupling reaction is reported in which isocyanides react with unprotected aldoses as biorenewable aldehyde components and acyclic amidines as amine components. The reaction proceeds through [4 + 1] cycloaddition of a conjugated imine intermediate with the isocyanide followed by dehydrative ring transformation of the resulting 4-amino-5-(polyhydroxyalkyl)imidazole to afford imino sugar-annulated imidazoles in excellent yields (86-95%). The procedure is performed in one pot in the presence of a nanoclay (K-10) catalyst, and can be expeditiously effected under solvent-free microwave-irradiation conditions.
报道了一种前所未有的Ugi三组分耦合反应,其中异氰化物与未受保护的醛糖(可再生生物醛组分)和无环酰亚胺(胺组分)反应。反应通过共轭亚胺中间体与异氰化物的 [4 + 1] 环加成,随后脱水环化转变为4-氨基-5-(多羟基烷基)咪唑,从而以优异的产率(86-95%)得到了含亚胺糖并环化的咪唑。该过程在纳米黏土(K-10)催化剂存在下一次性完成,并且在无溶剂微波辐照条件下可以迅速实现。