Optimization of the allylic oxidation in the synthesis of 7-keto-delta5-steroidal substrates.
A variety of delta5-steroids were converted into alpha, beta-unsaturated 7-ketones using a modification of the already known method of t-butyl hydroperoxide in the presence of copper iodide in acetonitrile. The same alteration was applied to another oxidative procedure, which had never been used before on steroidal substrates. The same oxidative agent was used in the presence of copper iodide, and tetra-n-butylammonium bromide was used as a phase-transfer catalyst in a two-phase system of water/methylene chloride. It was found that the allylic oxidation proceeded more efficiently when t-butyl hydroperoxide was added to the reaction mixture in portions. The initial addition of the total amount of oxidant or its dropwise addition afforded low yields. This observation contributes to the investigation of the reaction mechanism, and high-yield conversions of steroidal 5,6-enes into the corresponding conjugated 7-ones in short reaction times are reported.
Arsenou
Evaggelia S
ES
Laboratory of Pharmaceutical Chemistry, School of Health Sciences, Department of Pharmacy, University of Patras, 26 500 Patras, Greece.
Koutsourea
Anna I
AI
Fousteris
Manolis A
MA
Nikolaropoulos
Sotiris S
SS
D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D007454:Iodides / Q000737:chemistry; D007664:Ketosteroids / Q000138:chemical synthesis*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013997:Time Factors; D020122:tert-Butylhydroperoxide / Q000737:chemistry
D000498:Allyl Compounds; D007454:Iodides; D007664:Ketosteroids; D003300:Copper; D020122:tert-Butylhydroperoxide