The naturally occurring sugar mimetic alkaloids 1-deoxymannojirimycin (DMJ, 1) and 6-O-α-L-rhamnopyranosyl-DMJ (2) have each been prepared in a completely stereoselective manner from the cis-1,2-dihydrocatechol 3, itself obtained in enantiomerically pure form by microbial oxidation of chlorobenzene.