Herein
we report the first total syntheses of the trisaccharide-repeating
units of Pseudomonas chlororaphis subsp. aureofaciens UCM B-306 via a one-pot assembly of the core
trisaccharide structure. The rare-sugar-containing trisaccharide-repeating
units are comprised of d-bacillosamine, 2-amino-2-deoxy-d-galacturonic acid or amide, and d-rhamnose units
linked through three consecutive α-linkages. The total syntheses
of two repeating units were completed starting from d-mannose
via a longest-linear sequence of 27 steps in 5.8% and 4.4% overall
yields, respectively.