Total Synthesis of Conjugation-Ready Tetrasaccharide Repeating Units of a Multidrug-Resistant Pathogen Acinetobacter baumannii Strain 34 and O5.

Herein, we report the first total synthesis of conjugation-ready tetrasaccharide repeating units of Acinetobacter baumannii strain 34 and O5 comprising a common disaccharide motif [α-l-FucpNAc-(1→4)-α-d-GalpNAcA]. The installation of 1,2- cis linkages employing a disarmed 2-azido-d-galacturonic acid derivative as the donor is addressed here. The synthesis of the tetrasaccharide repeating units of A. baumannii strain 34 and O5 is accomplished via the longest linear sequences of 19 steps in 9.8% and 21 steps in 8.4% overall yields, respectively.