C-Glycosyl compounds represent a class of products used as chiral synthons' and as potential glycosidase inhibitors'. A number of methods have been devised for their synthesis3, but despite the biological importance of D-glucosamine, few C-glycosyl derivatives of this carbohydrate have been synthesized. cr-C-glycosyl compounds have been obtained selectively from protected 2acetamido-2-deoxy-o-glucose by a Wittig-type reaction and subsequent cyclization4. Other selective reactions include the reaction of mercuric cyanide with tri-0 acetyl-2-deoxy-2-phthalimido+n-glucopyranosyl bromide, to obtain selectively the p-D-glycosyl cyanide, described by Myers et al.'; Carcano et al.6 have prepared 2-amino-2-deoxy-a-u-glucopyranosylmethane from a protected D-arabinofuranosylbenzylamine, the key-step being vinylation with subsequent mercuri-cyclization. Grondin et al.' recently presented an original alternative by synthesizing selectively a-D-glucosaminylalkanes from C-l alkyl glycals. Several authors have reported difficulties in glucosaminylalkane synthesis and, except for the synthesis of Myers et aL5, the few stereoselective syntheses have concerned the (Y anomer. We decided, therefore, to apply to o-glucosamine some syntheses of C-glycosyl compounds previously described with other carbohydrates and leading stereospecifitally to the p anomer. The first is a Wittig-Horner-Emmons type reaction of the sodium salt of phosphonate 1 on unprotected monosaccharides. Davidson et aL8 have observed that such a reaction with D-glucose led to the two anomers of the C-glucofuranosyl derivative; these are converted into the thermodynamically more stable p-C-glucopyranosyl derivative by treatment with base. The second reaction is a Wittig-type * Corresponding author.