Stereoselective Synthesis of 2‐Deoxy‐2‐phenylselenenyl Glycosides from Furanoses: Implication of the Phenylselenenyl Group in the Stereocontrolled Preparation of 2‐Deoxy‐ribo‐ and 2‐Deoxy‐xylo‐oligosaccharides

Abstract

AbstractA series of 2‐deoxy‐2‐phenylselenenyl‐1‐thioglycosides were evaluated as a class of glycosyl donors that provide access to 2‐deoxyglycosides from furanoses. This short synthetic route involves olefination, selenonium ion mediated 6‐endo cyclization and glycosylation reactions. The cyclization reaction proceeds with complete regio‐ and stereoselectivity, which are enhanced by employing 3,4‐O‐isopropylidene as a cyclic bifunctional protecting group. The implication of the phenylselenenyl group at C‐2 in the stereocontrolled preparation of 2‐deoxyoligosaccharides is discussed. Its presence gives some insights into the likely pathway of glycosylation reactions by using 2‐deoxy‐2‐phenylselenenyl‐1‐thioglycosyl donors in comparison with the previously described 2‐deoxy‐2‐iodo derivatives. We also demonstrated that the glycosylation of 2‐deoxy‐2‐phenylselenenyl‐1‐thioglycosides is highly substrate dependent, as well as particularly effective in providing 2‐deoxy‐2‐phenylselenenyl‐β‐D‐gulo‐ and ‐β‐D‐allo‐glycosides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)