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Synthesis 2007(16): 2545-2558  
DOI: 10.1055/s-2007-983794
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Thiourea-Linked Glycooligomers that Mimic the Branching Patterns of Natural Oligosaccharides

José L. Jiménez Blancoa, Purificación Bootelloa, Ricardo Gutiérrez Gallegob, Carmen Ortiz Mellet*a, José M. García Fernández*c
a Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Profesor García González 1, 41012 Sevilla, Spain
Fax: +34(95)4624960; e-Mail: mellet@us.es;
b Pharmacology Research Unit, IMIM, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona Biomedical Research Park (PRBB), Doctor Aiguader 88 - office 225, 08003 Barcelona, Spain
c Instituto de Investigaciones Químicas, CSIC, Universidad de Sevilla, Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain
Fax: +34(95)4460565; e-Mail: jogarcia@iiq.csic.es;
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Publication History

Received 21 May 2007
Publication Date:
12 July 2007 (online)

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Abstract

A general blockwise strategy for the synthesis of accurately sequenced unnatural glycooligomers that can reproduce the branching patterns encountered in native oligosaccharides, based on the use of thiourea groups as intersaccharide bridges, is reported. The linear pseudooligosaccharide backbone is built from monosaccharide building blocks bearing a latent amino group and an isothiocyanate functionality through an iterative process in three steps per cycle that include: (i) thiourea-forming reaction, (ii) deprotection of the hydroxyl groups in the adduct and (iii) generation of a new amino group in the growing chain. Branching points are incorporated by inserting links bearing orthogonal amine functionalities at specific locations in the chain. The approach is illustrated by the preparation of glucopyranosylthiourea pseudoheptasaccharides that mimic the branching patterns of a phytoalexin elicitor oligosaccharine and of lentinan.

Key words

carbohydrate oligomers - oligosaccharides - sulfur - thioureas - isothiocyanates