Regiospecific O → N Acyl Migration as a Methodology to Access l-Altropyranosides with an 2,4-Differentiation.

Pseudaminic acid and its biosynthetic altropyranoside precursors are bacterial components currently being investigated toward novel antibacterial strategies. One structural feature associated with these naturally occurring flagellar carbohydrates is the different -acylation patterns on the two amido functionalities, posing a synthetic challenge. A new one-pot methodology is reported and a scope of diverse 2/4-differentiated analogs are presented via a Staudinger reduction-mediated regiospecific O3 → N4 acyl migration, followed by an autonomous 2-acylation.