Two-Directional Synthesis of Polycyclopropanes. An Approach to the Quinquecyclopropane Fragment of U-106305
作者:W. Scott McDonald、Christopher A. Verbicky、Charles K. Zercher
DOI:10.1021/jo961136b
日期:1997.3.1
The stereoselective preparation of three stereoisomeric tercyclopropanes and a quinquecyclopropane was investigated. Two of the tercyclopropanes were C-2-symmetric and were prepared efficiently through the two-directional application of Charette's reagent-stereocontrolled cyclopropanation methodology. The nonsymmetric tercyclopropane was prepared by an iterative one-directional application of the same reagent-mediated cyclopropanation method. It was shown that the reagent-controlled transformations are far more effective for the stereoselective preparation of the tercyclopropanes than are the reactions which rely upon the influence of the substrate stereocenters. A C-2-symmetric quinquecyclopropane, which possesses the repeating trans-syn stereochemistry, was prepared by iterative application of the two-directional strategy.