First Synthesis of Cytotoxic 8,9-Secokaurene Diterpenoids. An Enantioselective Route to (−)-<i>O</i>-Methylshikoccin and (+)-<i>O</i>-Methylepoxyshikoccin
作者:Leo A. Paquette、Dirk Backhaus、Ralf Braun、Ted L. Underiner、Klaus Fuchs
DOI:10.1021/ja971527n
日期:1997.10.1
A practical route for the totalsynthesis of 8,9-secokaurene diterpenes is described. The central step is the [3.3]sigmatropic rearrangement of spirocyclic intermediates such as 35, 40, and 41. All three compounds must necessarily respond identically to properly install the absolute configuration of the bridgehead methine carbon. The totalsynthesis of (−)-O-methylshikoccin (2b) was realized in 8% overall