Effective and mild method for converting 3β-hydroxysteroids to 3-keto steroids via DDQ/TEMPO

• A mild and efficient method for oxidizing of 3β-hydroxysteroids to the corresponding 3-keto steroids.
• This is a good method for the synthesis of 4,6-diene-3-one from the corresponding 3β-hydroxysteroids.
• Configurations of the oxidation compounds 2a, 2b, 3b, 2c, 2f and 2g were identified by X-ray diffraction.
• A possible mechanism is presented and discussed.

A mild and efficient oxidation of 3β-hydroxysteroids to the corresponding 3-keto steroids can be carried out at room temperature, using DDQ in the presence of catalytic TEMPO. Oxidation of saturated 3β-hydroxysteroids gave the corresponding ketones in excellent yield. The 5-unsaturated 3β-hydroxysteroids are oxidized selectively to 4-en-3-one or 4,6-diene-3-one derivatives according to the amount of DDQ in reaction. This is a good method for the synthesis of 4,6-diene-3-one from the corresponding 3β-hydroxy-5-ene steroids. Meanwhile, configurations of the oxidation compounds 2a, 2b, 3b, 2c, 2f and 2g were identified by X-ray diffraction. A possible mechanism is presented and discussed.