The addition of hypobromous acid to 3 beta, 17 beta-diacetoxy-4-estrene and an equilibration study involving neighboring group participation by the A-ring acetoxy group.

The reaction of 3 beta, 17 beta-diacetoxy-4-estrene with N-bromoacetamide in a two phase ether/water solvent mixture gave 5-bromo-4 beta, 17 beta-diacetoxy-5 alpha-estran-3 beta-ol as the major product (75%). Four minor products were also isolated and identified. These were: 4 alpha-bromo-3 beta, 17 beta-diacetoxy-5 alpha-estran-5-ol (5%), 5-bromo-3 beta, 17 beta-diacetoxy-5 alpha-estran-4 beta-ol (6%), 5-bromo-4 alpha, 17 beta-diacetoxy-5 alpha-estran-3 beta-ol (3%), and 4 beta-bromo-3 beta, 17 beta-diacetoxy-5 alpha-estran-5-ol (4%). The 5-bromo-4 beta, 17 beta-diacetoxy-5 alpha-estran-3 beta-ol was equilibrated by heating with oxalic acid in refluxing benzene for ca. 16 h to give a mixture of it and 5-bromo-3 beta, 17 beta-diacetoxy-5 alpha-estran-4 beta-ol in the ratio of 16:84 respectively. A similar equilibration mixture (14:86) was obtained under identical conditions when 5-bromo-3 beta, 17 beta-diacetoxy-5 alpha-estran-4 beta-ol was the starting material.