Influence of a δ-lactam-type cyclic protecting group on the reactivity of a 4-hydroxy glycosyl acceptor derivative of d-glucosamine

Abstract

A new 4-hydroxy glycosyl acceptor derivative of d-glucosamine containing a lactam-type N-protecting group was synthesized. The new glycosyl acceptor containing a hydroxy group at the C(4) atom was shown to be highly reactive in the glycosylation despite the presence of the amide (lactam) NH group. The high efficiency of the synthesized acceptor derivative is apparently attributed to the transformation of the (Z)-amide function that is present in amino sugar derivatives containing an acyclic acyl N-protecting group into the (E)-amide group in derivatives containing a lactam-type cyclic N-protecting group. This transformation leads to a radical change in the hydrogen bonding conditions and the character of molecular association. The observed effect can be employed to design new N-protecting groups providing high reactivity of glycosyl acceptor derivatives of D-glucosamine.