Acetolysis of 6-Deoxysugar Disaccharide Building Blocks: exo versus endo Activation

Two different protocols for the mild and selective acetolysis of 6-deoxysugar methyl disaccharides under thermodynamic or kinetic control have been developed. The structures of the disaccharides obtained depend on the protocol used and, in the kinetically controlled cases, on the 6-deoxysugar configuration and protecting group pattern too. The behavior of 6-deoxyhexose oligosaccharides of different series (rhanino, quinovo, and fuco) under these two reaction conditions has been studied and rationalized based on the competition between exo versus endo oxygen activation in the acetolysis mechanism. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)