De Novo Design and Asymmetric Synthesis of a -1/2 Benzodioxin Fused Glycoside Analogue of Lincomycin.

An designed benzodioxin fused analogue of a des-(1-hydroxyethyl)-lincomycin analogue was synthesized in a asymmetric fashion from an achiral acylfuran, a 4-(-Pr)--methyl-proline, and catechol. The synthesis of the 6-amino-galactose portion of the lincomycin analogue necessitated the development of a novel stereospecific tandem Pd-glycosylation/1,4-addition reaction between catechol and an -Cbz-protected 6-amino-pyranone with a Pd-π-allyl leaving group at the -1 position. The desired -stereochemistry was installed by a subsequent stereoselective ketone reduction, alcohol elimination, and diastereoselective dihydroxylation of the -3/4 alkene.