Synthesis and oxidation of pregna‐3,5‐dien‐20‐ols and ‐20‐one and selective reduction of pregna‐3,5‐dien‐20‐one

Pregna‐3,5‐dien‐20‐one ( 4 ) and (20S)‐ and (20R)‐pregna‐3,5‐dien‐20‐ol ( 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 ), 6β‐hydroxyprogesterone ( 6 ) and 5α‐pregnane‐3,6,20‐trione ( 7 ). With L‐selectride as reducing agent, reduction of 4 led to 2 and 3 in a ratio of about 1:1. However, some reducing agents gave a higher ratio of isomer 3 .