Synthesis of the α‐methyl ketoside of 5‐amino neuraminic acid methyl ester and its corresponding 5‐myristoyl and 5‐cyclopropanoyl derivative

Abstract This communication describes the first synthesis of the α‐methyl ketoside of an N ‐unprotected neuraminic acid in the form of its methyl ester (Neu5NH 2 1Me‐α‐2Me) ( 5a ). This compound is a valuable intermediate for the synthesis of unnatural N ‐substituted sialic acids. Syntheses of Neusmyristoyl1me‐α‐2Me ( 5b ) and Neuscyclopropanoyl1me‐α‐2Me ( 5c ) are presented.