1. Highly Stereocontrolled Total Synthesis of β-<scp>d</scp>-Mannosyl Phosphomycoketide: A Natural Product from Mycobacterium tuberculosis
- Author
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Louise Scharf, Nan-Sheng Li, Erin J. Adams, and Joseph A. Piccirilli
- Subjects
Biological Products ,Natural product ,biology ,Stereochemistry ,Organic Chemistry ,Total synthesis ,Stereoisomerism ,Mycobacterium tuberculosis ,biology.organism_classification ,Phytol ,chemistry.chemical_compound ,Glycolipid ,chemistry ,Diimide ,Molecule ,Glycolipids ,Propionates ,Chirality (chemistry) - Abstract
β-D-mannosyl phosphomycoketide (C32-MPM), a naturally occurring glycolipid found in the cell walls of Mycobacterium tuberculosis, acts as a potent antigen to activate T-cells upon presentation by CD1c protein. The lipid portion of C32-MPM contains a C32-mycoketide, consisting of a saturated oligoisoprenoid chain with five chiral methyl branches. Here we develop several stereocontrolled approaches to assemble the oligoisoprenoid chain with high stereopurity (>96%) using Julia-Kocienski olefinations followed by diimide reduction. By careful choice of olefination sites, we could derive all chirality from a single commercial compound, methyl (2S)-3-hydroxy-2-methylpropionate (>99% ee). Our approach is the first highly stereocontrolled method to prepare C32-MPM molecule with >96% stereopurity from a single >99% ee starting material. We anticipate that our methods will facilitate the highly stereocontrolled synthesis of a variety of other natural products containing chiral oligoisoprenoid-like chains, including vitamins, phytol, insect pheromones, and archaeal lipids.
- Published
- 2013
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