CONFORMATIONAL-ANALYSIS OF NITRILIUM INTERMEDIATES IN GLYCOSYLATION REACTIONS

In order to shed light on the stereoselectivity of acetonitrile-mediat ed glycosylation reactions, the nitrilium intermediates have been gene rated at -30-degrees-C in acetonitrile-d3 and studied by H-1, C-13, an d N-15 NMR spectroscopy. Conjointly, molecular modeling of the interme diates by molecular mechanics has been performed with the CHARMm force field. All the evidence suggests that only nitrilium derivatives with the a configuration are formed.