Sialic acid is a type of sugar present in the sugar chain of human cells, and while being involved in cell-cell communication in immunity and the like, it is also an infection target for bacteria and viruses.Therefore, although it is regarded as an important target for pharmaceutical development, there is a problem in its chemical synthesis.

　Sialic acid binds to other molecules in the horizontal direction (α bond) and in the vertical direction (β bond).Curiously, natural sugar chains have only α-bonds, but if you try to make them artificially, only β-bonds will be formed. No one has ever succeeded in completely creating the α-bonded sialic acid.

　This time, the research group thought that if sialic acid was modified so that it could only be bonded in the horizontal direction, only α-bonded sialic acid could be produced. Developed "bridge sialic acid" connected by.As a result, as expected, the carbon chain of the "bridge part" became a vertical wall, and it became possible to synthesize only α-bonded sialic acid.

　The research group went on to use bridging sialic acid to successfully synthesize all sialic acid-containing compounds that were not possible with conventional methods.We have also succeeded in synthesizing non-naturally occurring C-glycosides, which are useful for vaccine development, and gangliosides (glycolipids), which have been regarded as one of the most difficult issues.We also succeeded in synthesizing the world's longest sialic acid pentamer, which is a combination of five sialic acids.

　If the synthetic method developed this time can produce a large amount of α-bonded sialic acid-containing sugar chains, it is expected to be of great help in elucidating life phenomena, infections and diseases related to sugar chains, and researching vaccines and drug development. Has been done.

Paper information:[Science] Constrained Sialic Acid Donors Enable Selective Synthesis of α-Glycosides