Total Synthesis of the Phenolic Glycolipid Mycoside B and the Glycosylatedp-Hydroxybenzoic Acid Methyl Ester HBAD-I, Virulence Markers ofMycobacterium tuberculosis
The phenolic glycolipid mycoside B, present in Mycobacterium bovis and hypervirulent strains of Mycobacterium tuberculosis, has been synthesized for the first time. Multiple methyl groups were introduced by the extensive use of catalytic asymmetric 1,4-addition reactions, asymmetric hydrogenation of a -keto ester afforded the basis for the central 1,3-diol moiety, and introduction of the 2-O-methyl--L-rhamnoside unit was achieved by stereoselective glycosylation with p-iodophenol and subsequent Sonogashira coupling, providing a basis for the generation of analogues. In addition, the related monosaccharide HBAD-I, present in the same species, has been efficiently synthesized for the first time by selective methylation of the hydroxy group at C-2 of a rhamnoside.