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Synthesis 2010(23): 4051-4056  
DOI: 10.1055/s-0030-1258252
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Carbohydrate Building Blocks in the Ugi Three-Component Coupling Reaction: Convenient Annulation of Iminosugars on Imidazoles

Vijai K. Raia,b, Santosh Singha, Pankaj Singha, Lal Dhar S. Yadav*a
a Green Synthesis Laboratory, Department of Chemistry, University of Allahabad, Allahabad 211 002, India
b School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir 182 320, India
Fax: +91(532)2460533; e-Mail: ldsyadav@hotmail.com;
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Publikationsdatum:
14. September 2010 (online)

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Abstract

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.

Key words

heterocycles - carbohydrates - cyclizations - multicomponent reactions - catalysis - Ugi reaction