Synthesis of the N-Acyl Amycolose Moiety of Amycolamicin and Its Methyl Glycosides

The N-acyl amycolose moiety incorporated in amycolamicin, a broad-spectrum antibacterial natural product produced by soil actinomycetes, and its two anomeric methyl glycosides have been synthesized enantioselectively each in 12 steps from a known methyl ( R)-lactate derivative by exploiting a diastereoselective nucleophilic addition of a p-methoxybenzyloxy-substituted vinyllithium reagent to an α,β-bisalkoxy ketone intermediate to provide the corresponding tertiary alcohol as a single diastereomer. The three sugar derivatives are known as cytotoxic degradation products of amycolamicin.