An enantioselective synthesis of the naturally occurring lipid, guggultetrol, is described with an overall yield of 24% starting from commercially available 1-pentadecanol in ten linear steps. The key chiral-inducing steps include a Sharpless asymmetric epoxidation of allylic alcohol and a dihydroxylation of an alpha,beta-unsaturated ester. (C) 2010 Elsevier Ltd. All rights reserved.
Total Synthesis of α-1<i>C</i>-Galactosylceramide, an Immunostimulatory <i>C</i>-Glycosphingolipid, and Confirmation of the Stereochemistry in the First-Generation Synthesis
作者:Zheng Liu、Hoe-Sup Byun、Robert Bittman
DOI:10.1021/jo201450s
日期:2011.11.4
A nonisosteric alpha-C-glycoside analogue of KRN7000 (alpha-1C-GalCer, 1) was reported to induce a selective type of cytokine release in human invariant natural killer cells in vitro. We report here a very concise synthetic route to 1 and its analogue 1'. The key steps include olefin cross-metathesis, Sharpless asymmetric epoxidation, and epoxide opening by NaN3/NH4Cl. Inversion of configuration at the amide-bearing carbon in the phytosphingosine backbone constructed by epoxide opening in our previous synthesis of 1 was verified, indicating that remote group participation is not involved during the epoxide-opening reaction.