The Reduction of Steroid 2α-Fluoro 4-En-3-ones

Article abstract of DOI:10.1021/jo00248a028

Reduction of testosterone with potassium tri-(R,S)-sec-butylborohydride gives predominantly the allylic 3β-alcohol, while 2α-fluorotestosterone is converted solely to 2α-fluoro-4-androstene-3α,17β-diol, and 2α-fluoro-4-androstene-3,17-dione to 2α-fluoro-3α-hydroxy-4-androsten-17-one.Reduction of testosterone with (R,R)- or (S,S)-Rh-DIOP and dihydrosilanes give predominantly allylic alcohols, while with the same catalysts and monohydrosilanes no allylic alcohols are found, the 4-double bond being instead reduced.The chirality of the DIOP reagents contributes only to a minor extent to stereoselectivity of 3-ketone reduction.