Abstract The lactam 21 was obtained in an overall yield of 72% from the hydroxy amide 16 by oxidation with the Dess-Martin periodinane, acid-catalysed isomerization of the oxidation products in toluene, whereupon 18/19 precipitated, and reductive dehydroxylation of 18/19 (Et 3 SiH/BF 3· OEt 2; Scheme 1). The amide 16 was obtained by ammonolysis of the N- acetylglucosamine-derived lactone 15. Depending on the oxidation method, 16 yielded ...