Pregna-3,5-dien-20-one (4) and (20s)-and (20R)-pregna-3,5dien-20-01 (2 and 3) were synthesized from progesterone. Oxidation of a mixture of 2 and 3 with Jones reagent gave 4, while a large excess of Jones reagent afforded besides 4, 6-oxoprogesterone (5), 60-hydroxyprogesterone (6) and 5apregnane-3,6,20-trione (7). With L-selectride as reducing agent, reduction of 4 led to 2 and 3 in a ratio of about 1:l. However, some reducing agents gave a higher ratio of isomer 3.