[摘要]：A CH2-linked a(2,3)sialylgalactose analog was efficiently synthesized using an Ireland-Claisen rearrangement, which was developed recently by our group for constructing a CF2-sialoside. The reaction conditions of the rearrangement were optimized for a-stereoselective formation of the CH2-sialoside. On the basis of the obsd. temp. effects, the origin of the stereoselectivity of the Ireland-Claisen rearrangement is discussed. Moreover, reconstruction of the 2a-hydroxyl group on the galactose unit of the rearrangement product was achieved by means of stereoselective dihydroxylation and deoxygenation.
