From polymer to size-defined oligomers: a highly divergent and stereocontrolled construction of chondroitin sulfate A, C, D, E, K, L, and M oligomers from a single precursor: part 2.

An efficient, stereocontrolled, and highly divergent approach for the preparation of oligomers of chondroitin sulfate (CS) A, C, D, E, K, L, and M variants, starting from a single precursor easily obtained by semisynthesis from abundant natural polymer is reported for the first time. Common intermediates were designed that allowed the straightforward construction of O-sulfonated species either on the D-galactosamine unit (CS-A, -C, and -E) or on both D-glucuronic acid and D-galactosamine units (CS-D and CS-K, -L, and -M). This strategy represents a successful improvement and brings a definitive answer toward the synthesis of such complex molecules with numerous relevant biological functions.