Neoglycoprotein cancer vaccines: synthesis of an azido derivative of GM3 and its efficient coupling to proteins through a new linker

A GM3 derivative having an azido group on its reducing end was synthesized in nine separate steps, and it was then conjugated to proteins by a new linker. Therefore, the azido group was reduced to a free amino group, which was followed by the introduction of a 4-pentenoyl group. The carboncarbon double bond of the 4-pentenoyl group was ozonolyzed to form a carbonyl group, and GM3 was thus linked to proteins via the carbonyl group by reductive amination.