An easy route to seven-membered iminocyclitols from aldohexopyranosyl enamines

Abstract

A new stereocontrolled and high yielding synthesis of biologically active polyhydroxyperhydroazepines is reported starting from easily available glycosylenamines (D- gluco, D- manno, and D- galacto configurations), which are transformed into 1,6-azaanhydropyranose derivatives. O- and N-Deprotection of the latter, followed by reduction with sodium cyanoborohydride, gives the target chiral iminocyclitols. The method is based on the capacity of the dialkoxycarbonylvinyl group to stabilize an amide ion, and the only limitation is the necessity for the starting glycosylenamine to have β-D-configuration. The inhibitory activity of several intermediate iminocyclitols and aldopyranosylenamines on different α- and β-glycosidases is also reported.