Reaction of partially protected aldoses with stabilized arsenic ylides: Synthesis of E unsaturated acyclic derivatives and C-glycosyl derivatives

The reaction of partially protected aldoses with (carbomethoxymethyl)triphenylarsonium bromide and zinc in toluene gave E alpha,beta-unsaturated acyclic esters. When intramolecular transesterification occurred, bicyclic 1,4-lactone derivatives were formed concurrently. Otherwise, using these non alcaline conditions, olefination did not favour the formation of C-glycosyl derivatives. On the other hand, when the reaction was performed with (carbomethoxymethylene)triphenylarsorane in toluene, followed by the addition of n-butyllithium, bicyclic derivatives were obtained rapidly in good yields. Moreover, when cyanomethyltriphenylarsonium bromide was used in place of (carbomethoxymethyl)triphenylarsonium bromide, the corresponding E aldooctenonitriles were produced in satisfactory yields.