for the synthesis of 2,3-unsaturated C-glycosides. Various nucleophiles such as allyl trimethylsilane, triethylsilane, trimethylsilyl cyanide, trimethylsilyl azide and heterocycles such as thiophene and furan reacted smoothly with glycals in the presence of catalytic amount of ruthenium trichloride under mild reaction conditions.
Glycals react smoothly with furan in the presence of a catalytic temperature amount of indium trichloride at ambient to afford predominantly the C-3-substituted glycals in high yields. Other heteroaromatics including 2-benzyloxymethylfuran. thiophene and N-Boc protected indole afford exclusively C-I-glycosides in good yields with high beta-selectivity under similar reaction conditions. (C) 2002 Elsevier Science Ltd. All rights reserved,