Synthesis of disaccharide and trisaccharide substructures of an A. baumannii lipooligosaccharide core.

Identification and synthesis of highly conserved glycans is a priority for understanding chemical immunology as it applies to drug-resistant pathogens such as Gram-negative Acinetobacter baumannii. Herein, we report on our initial efforts aimed toward the synthesis of a highly conserved lipooligosaccharide core isolated originally from A. baumannii ATCC 19606. Key steps in the syntheses include a regioselective acetonide cleavage and a stereoselective and regioselective O-glycosylation of the 4-position of the 8-carbon sugar "Kdo."