Mohammed Lakhrissi

Efficient conditions for the synthesis of C-glycosylidene derivatives: a direct and stereoselective route to C-glycosyl compounds

Abstract Efficient conditions for the synthesis of C -glycosylidene compounds from lactones based on Wittig reactions of cyanomethyl triphenylphosphoranylidene involving microwave heating are described: subsequent stereoselective reduction of the anomeric olefins gave the corresponding C -glycosides in good yields with high stereocontrol.

A short route to α-chloro- and α-azido-ulosonic esters

Abstract A two step route to α-chloro-ulosonic esters from lactones involving the reaction of dichloroolefins with m -chloroperbenzoic acid in dichloromethane is described. Subsequent substitution of chlorine by the azide ion yields the corresponding anomeric azido-esters, which may be useful intermediates for the preparation of “anomeric amino-acids” and related compounds.

Facile synthesis of fused furanosyl β-amino acids from protected sugar lactones: incorporation into a peptide chain

Abstract The synthesis of fused furanosyl β-amino esters from protected sugar lactones is described, using the combination of a Wittig type reaction and 1,4-addition of benzylamine on the resulting glycosylidenes. This sequence of reactions afford either N-glycosyl-3-ulosonic acid esters, which are the β-analogues of anomeric sugar α-amino esters, or open-chain sugar β-enamino esters, when a retro-Michael reaction takes place after addition of benzylamine. Incorporation of the fused furanosyl β-amino ester 2a into a peptide chain is also described.

Wittig olefination of partially protected sugar lactones: A direct entry to dioxabicyclic and trioxatricyclic systems

Partially protected sugar lactones reacts with stabilized phosphoranes at high temperature yielding activated olefins which undergo subsequent 1,4-addition to give bicyclic adducts, simultaneous furan formation being also observed.

Unusual behaviour of some γ- and δ-lactones towards dichloromethylenation using tris(dimethylamino)phosphine–tetrachloromethane

Lactones derived from D-glucose, D-mannose and L-ascorbic acid reacted unexpectedly with tris(dimethylamino)phosphine–tetrachloromethane to give, respectively, dichloroalkene, anomeric vinyl chloride or acyl chloride; this behaviour supports an ionic mechanism for the alkenation.

Unusual chlorination of some olefins with meta-chloroperbenzoic acid in dichloroethane

Abstract In the presence of poorly reactive olefins such as dichloroolefins, meta-chloroperbenzoic acid reacts with dichloromethane, probably via a radical mechanism, to produce a powerful chlorinating species which behaves like other chlorinating agents.