Abstract
Derivatives of 3beta-amino-5-cholestene (3beta-cholesterylamine) are of substantial interest as cellular probes and have potential medicinal applications. However, existing syntheses of 3beta-amino-5-cholestene are of limited preparative utility. We report here a practical method for the stereoselective preparation of 3beta-amino-5-cholestene, 3beta-chloro-5-cholestene, 3beta-bromo-5-cholestene, and 3beta-iodo-5-cholestene from inexpensive cholesterol. A sequential i-steroid/retro-i-steroid rearrangement promoted by boron trifluoride etherate and trimethylsilyl azide converted cholest-5-en-3beta-ol methanesulfonate to 3beta-azido-cholest-5-ene with retention of configuration in 93% yield.