Computational elucidation on regio- and stereoselectivity on glycosylation of alcohols by N-Cbz-imino glycal-derived allyl N-nosyl aziridines

A few years ago, was published the glycosylation of alcohols by the new diastereoisomeric d,l-6-deoxy-N-Cbz-imino glycal-derived allyl N-nosyl aziridines affords, after deprotection of the 4-N-nosylamino group, the corresponding 2,3-unsaturated-N-Cbz-imino-O-glycosides bearing a free amino group on C4 through a completely 1,4-regio- and substrate-dependent stereoselective glycosylation process. However, were not clear why the reaction occurs with high 1,4-regio- and stereoselectivity. To clarify the effects that direct the 1,4-regio- and stereoselectivity of this reaction, we performed a complete theoretical investigation of their transition states. The results showed that the selectivity on stereochemistry of the reaction can be explained by differences in the relative stability of the reaction products and transition states proposed.