Stereoselective Synthesis of 1-C-Diethylphosphonomethyl and -difluoromethyl Iminosugars from Sugar Lactams

Abstract

A strategy allowing the straightforward synthesis of 1-C-phosphonomethyl and 1-C-phosphonodifluoromethyl iminosugars is reported. Conversion of sugar lactams to the corresponding imines with Schwartz’s reagent followed by their reaction with LiCH2P­(O)­(OEt)2 and LiCF2P­(O)­(OEt)2 stereoselectively afforded the 1,2-cis and 1,2-trans glycosyl phosphonates, respectively, in modest to good yields. Application of this methodology to C-2 orthogonally protected sugar lactams paved the way to 2-acetamido- and 2-deoxy-1-C-phosphonomethyl iminosugars.