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