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Keywords:

  • acylhydrazones;
  • cycloaddition;
  • enantioselectivity;
  • Lewis acids;
  • MS-153;
  • silicon

Abstract

Our previously reported chiral silane-promoted enol ether-acylhydrazone [3+2] cycloaddition reaction has been applied to a brief and efficient synthesis of the neuroprotective agent MS-153. Unsatisfactory and variable levels of efficiency and enantioselectivity with the requisite acetaldehyde-derived acylhydrazone occasioned a modification to the chiral silane Lewis acid, which led to the key cycloaddition step proceeding with excellent efficiency (85 % yield) and enantioselectivity (≥98 % ee).