The reaction of 4-chloro-Δ⁴-3-oxosteroids (Ia, c, e) with dimethyl sulfoxide were shown to yield Δ^{4, 6}-3-oxosteroids (IIg, h, i). These were accompanied by the 3, 6-dione (III) and Δ⁴-3, 6-dione (IV) in the case of 19-methylsteroid, by estra-1, 3, 5 (10)-triene-3, 17β-diol 17-acetate (VII) from 19-norsteroid, and by Δ⁴-3-oxo-6β, 19-oxide (VI) from 19-hydroxymethylsteroid. With dimethylsulfoxide 4-bromo-Δ⁴-3-oxosteroids (Ib, d, f) gave the 4-bromo-Δ^{4, 6}-3-oxosteroids (IIb, d, V) under the same reaction conditions. Bromination of 17β-acetoxyandrosta-4, 6-dien-3-one (IIg) in dimethylsulfoxide afforded the bromotrienone (X), the 2α-bromo (VIII) and 2, 2-dibromo (IX)-derivatives of IIg being intermediates in the conversion.