Here we report the first total synthesis of the conjugation-ready
tetrasaccharide repeating unit of Shewanella japonica type strain KMM 3299T. The presence of rare deoxyamino
sugars and installation of three consecutive 1,2-cis glycosidic linkages makes the synthesis formidable. The challenging
late-stage oxidation was overcome by using a galacturonate donor.
The total synthesis was completed via a longest linear sequence of
22 steps in an overall yield of 3.5% starting from d-mannose.