Synthetic approach toward complexity of sialic acid-containing glycans

The biological relevance of sialic acid-containing glycans (sialo-glycans) to various interactions at the cell surface has increased the demand for the supply of structurally defined sialo-glycans. Due to their unique structures, the stereoselective synthesis of glycosides of sialic acid is inherently difficult, which makes the synthetic approach to synthesize diverse and complex sialo-glycans far from successful. However, the gap between the chemical and natural synthesis of complex sialo-glycans is narrowing through the emergence of synthetic methods. This review highlights recent progress made in the synthesis of complex sialo-glycans via cutting-edge synthetic methods. The development of versatile synthetic units of sialic acid allowed to synthesize highly complicated sialic acid-containing molecules.