An Improved Synthesis of 3β-Cholesteryl Halides Involving i-Steroid and Retro-i-Steroid Rearrangements

Abstract

Treatment of 3β-cholesteryl methanesulfonate with tetrabutylammonium halides in the presence of BF3·Et2O provides a mild and efficient method for the preparation of 3β-cholesteryl halides via i-steroid and retro-i-steroid rearrangements. The utilization of tetrabutylammonium halides avoided the moisture sensitivity and lowered the cost of reagents for the reported method based on trimethylsilyl halides.