Stereoselective synthesis of C-glycosylphosphonates from their ketols. Reconsideration of an abandoned route

Isosteric phosphonate analogues of glycosyl 1-phosphates have been obtained by addition of LiCH2P(O)(OMe)2 to glyconolactones followed by Et3SiH-TMSOTf reductive dehydroxylation of the resultant ketols. The compounds prepared include four β-linked pyranose derivatives (D-galacto, 2-azido-2-deoxy-D-galacto, D-gluco, D-manno) and one β-linked furanose derivative (D-manno). In the latter case the ketol was activated as its 2-acetate. In agreement with an observation in another laboratory, the dehydroxylation of a model ketol phosphonate failed with the use of Et3SiH-BF3.Et2O. Copyright (C) 2000 Elsevier Science Ltd.