Some Reactions of Steroidal α-Bromo Ketones

16α-Bromoandrostan-3β-ol-17-one (I) is converted by methoxide ion into the dimethyl ketal of 3β-16α-dihydroxyandrostan-17-one (II). The 16β-bromo epimer la and the 5,6-dehydro analog lb undergo the same transformation. The structure of the ketal II was apparent from its hydrolysis to 16α-hydroxy-17-ketone (III), its acetylation, its reduction to the 16α,17β-diol (VI), and its nmr spectra. The reaction of bromo ketone I with ethoxide takes a different course. The stereochemical results of the reaction of methoxide with I and Ia are discussed assuming 17β-methoxy-16α,17β-epoxyandrostan-3β-ol (VIII) as an intermediate. Some ring-opening reactions of acetoxy epoxides are discussed.