Cellobiose-Derived β-Linked Disaccharide Donor Enables Convergent Syntheses of Acinetobacter baumannii K91 and K25 Capsular Trisaccharides.

Herein, we report a convergent 2 + 1 strategy for the synthesis of the Acinetobacter baumannii K91 and K25 CPS trisaccharide repeating units. A cellobiose-derived β-linked disaccharide donor bearing the requisite β-1,4-glycosidic framework enabled divergent assembly of both targets, while late-stage functional-group interconversions provided the β-ManNAcA-containing motifs. This route minimizes glycosylation steps and offers efficient access to structurally defined CPS oligosaccharides.