Imino glycals in synthesis:: Preparation of novel deoxymannojirimycin analogues

The synthesis of imino glucal 2 from tetra-O-benzyl-D-glucopyranose in 7 steps is described. This imino sugar building block is converted into conformationally constrained deoxymannojirimycin analogue (+)-9 by means of a stereocontrolled cyclopropanation followed by a two step deprotection sequence. Regioselective fission of the cyclopropane ring prior to deprotection provides access to related analogue (+)-11.