Synthesis of a Six-Carbon Sialic Acid Using an Indium-Mediated Coupling

[reaction: see text] The synthesis of a six-carbon truncated sialic acid is described. A key step in the synthesis was an indium-mediated allyl addition to a serine-derived aldehyde. Careful choice of protecting groups was found to be necessary in order to prevent unwanted side reactions throughout the sequence. The truncated sialic acid was obtained in a form suitable for activation as a glycosyl donor.