Abstract
A novel and efficient method was developed for the preparation of bromo-substituted cholestenone, including 6β-bromocholestenone and 2α,6β-dibromocholestenone. The key step in this synthesis is a very mild method for the transformation of 5α,6β-dibromocholesterol into the 6β-bromocholestenone by treatment with NaClO/NaBr/TEMPO, followed by dehydro-bromination with Et3N. Bromination at C-2 with NBS/BPO (benzoyl peroxide) gave the 2α,6β-dibromo cholestenone. This was used in a synthesis of 1α-hydroxycholesterol.
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