Expeditious synthesis of C-glycosyl conjugated dienes and aldehydes from sugar lactones

Several C-glycosyl conjugated dienes were prepared in two steps from protec ted sugar lactones via addition of allylmagnesium chloride and the subseque nt dehydration. A sequence of allylic addition, ozonolysis and dehydration led to the corresponding glycosyl conjugated aldehydes. These conjugated fu nctionalities can be used as diagnostic chromophores for sugar synthesis an d purification. The synthetic studies of glycosyl dienes were also pursued. Hydroboration of a sugar diene led to tither homoallylic alcohol or spiroa cetal depending on the workup conditions. (C) 2001 Elsevier Science Ltd. Al l rights reserved.