Efficient stereocontrolled synthesis of C-glycosides using glycosyl donorssubstituted by propane 1,3-diyl phosphate as the leaving group

a- and beta -Glycosyl cyanides, per-O-acetyl-1,2-O-1-cyanoethylidenes and C -allyl glycopyranosides were efficiently prepared by treatment of 2,3,4-tri -O-acetyl-alpha,beta -L-rhamno-, L-fuco- and 2,3,4,6-tetra-O-acetyl-alpha,b eta -D-galactopyranosyl propane-1,3-diyl phosphates with trimethylsilyl cya nide (TMSCN) and allyltrimethylsilane in the presence of trimethylsilyl tri flate (TMSOTf). Similarly 2,3,4,6-tetra-O-benzyl-alpha,beta -D-manno- and D -glucopyranosyl propane-1,3-diyl phosphates were employed in the synthesis of C-glycosides. (C) 2001 Elsevier Science Ltd. All rights reserved.