Hydroperoxy steroids

Copper halides catalyze the radical [2,3] sigmatropic rearrangement of the 5a-hydroperoxy steroids and the subsequent reaction to the corresponding unsaturated ketone1. 

A recent communication described the cleavage of 17a-hydroperoxy-20-keto steroids with base to give 17-ketoandrostanes in good yield. Since such hydroperoxides are now accessible from 20-ketopregnanes in one step vide infra), this constitutes a convenient two-step degradation process. In practice, the intermediate hydroperoxide need not be isolated. Other enolizable... 

This selenium-dependent enzyme [EC 1.11.1.9] catalyzes the reaction of two molecules of glutathione with hydrogen peroxide to produce glutathione disulfide and two water molecules. Hydrogen peroxide can be replaced by steroid and lipid hydroperoxides, albeit not as effectively (nevertheless, this enzyme is not identical with phospholipid-hydroperoxide glutathione peroxidase [EC 1.11.1.12]). However, the hydroperoxy products formed by the action of lipoxygenase [EC 1.13.11.12] are not substrates. 

Other steroid systems have also been investigated. Methyl groups at the bridgehead position always shield the /3-side and thus promote exclusive a-attack. Additionally, for the triacetoxy derivative 1268, an intermediate in the synthesis of a-ecdysone, and for 3j6-acetoxy-8(14)-cholesten-6-one (14)69, the regioselectivity of the ene reaction with singlet oxygen is high. In both cases only the y-hydroperoxy-a,/J-unsaturated ketone is formed. 

In einer ahulich verlaufenden Reaktion wird das Steroid III durch Licht in 3 -Hydroxy-7a.-hydroperoxy-17j3-acetyl-androsten-(5) (IV) umgclagert2 ... 

Covey, D.F., W.F. Hood, and P.C. McMullan (1986). Studies of the inactivation of human placental aromatase by 17a-ethynyl-substituted lOP-hydroperoxy and related 19-nor steroids. Biochem. Pharmacol. 35, 1671-1674. 

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