Synthesis of the N‐Amykitanosyl Tetramic Acid Moiety of Amycolamicin

Abstract

AbstractAn improved five‐step synthetic route from l‐fucose to an N‐glycosyl l‐valine methyl ester has been developed. The new route involves glycosidation of l‐fucose with phenol in a β‐selective manner without protection/deprotection steps and one‐pot stereochemical inversion of a secondary alcohol intermediate and is superior to our previous one both in the number of steps and in overall yield. An N‐glycosyl l‐valine benzyl ester, prepared from l‐fucose in an analogous way, has been elaborated into an N‐amykitanosyl tetramic acid derivative, Li's synthetic intermediate for amycolamicin, via a four‐step sequence which features the utilization of Bestmann's ylide to stereoconvergently construct an N‐glycosyl tetramic acid intermediate in a single step, opening of a cyclic carbonate ring with an amine to regioselectively install a carbamate functionality, and visible light‐mediated oxidative debenzylation of an N,N‐dibenzyl carbamate.