Stereocontrolled and convergent entry to CF2-sialosides:: Synthesis of CF2-linked ganglioside GM4

Sialidase-resistant ganglioside analogues having biological activities similar to those of natural gangliosides are expected to be important probes for clarifying the biological functions of gangliosides. Focusing on difluoromethylene-linked (CF2-linked) alpha(2,3) sialylgalactose as a core structure of sialidase-resistant ganglioside mimics, we have developed novel, stereocontrolled, and efficient methodologies to synthesize CF2-sialosides based on Ireland-Claisen rearrangement. CF2-linked alpha(2,3)sialylgalactose and CF2-linked GM4 were synthesized.