The Synthesis and Conformational Analysis of α-Bromo-16-ketones of 13α-Androstanes

Abstract

15α- and 17α-bromo-3β-hydroxy-5α, 13α-androstan-16-one acetates (VI, VII) were synthesized starting from the parent 16-oxosteroid (Ib) by way of the enol acetate (V). Configuration of both bromine atoms introduced was established to be α by the standard method of Fieser and Ettorre. These two positional isomers were readily distinguished by leading to the Δ^15- and Δ¹⁶-unsaturated compounds (X, XI), respectively. On the basis of infrared, ultraviolet, rotatory dispersion and circular dichroism spectral data, the nature of 15α- and 17α-bonds and the conformation of rign D with a ketone at C-16 were discussed.