BiBr3‐Promoted Activation of Peracetylated Glycosyl Iodides: Straightforward Access to Synthetically Useful 2‐O‐Deprotected Allyl Glycosides

Abstract

AbstractSubstoichiometric amounts of BiBr3 are able to promote anomeric activation of acetylated glycosyl iodides. This reactivity can be exploited for straightforward access to allyl glycosides unprotected at the O‐2 position. The reported protocol appears to be convenient in comparison with the pre‐existing ones in that shorter experimental times are needed and the use of strong acids is avoided. Suitable structural features of substrates (6‐deoxy sugars or use of benzoyl or methoxycarbonyl 2‐O‐participating groups) switch the process to a preferential glycosidation without deprotection at the O‐2 position.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)