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Steroidal 3,5-diene is an important structural motif in steroid drugs. In this report, an iridium-catalyzed reduction-elimination of readily available steroidal 4-en-3-ones is realized to prepare steroidal 3,5-dienes. At a low catalyst loading (S/C = 200), heating 4-en-3-ones in a water-mixed organic solvent with formic acid without inert atmosphere protection afforded the desired 3,5-dienes in moderate to excellent yields. In a gram-scale preparation, recrystallization is used instead of column chromatography to purify products. Excellent functionality tolerance and regioselectivity are featured. Structural moieties such as alkanols (primary, secondary and tertiary), esters (except for formate), tolylates, and ketones (endocyclic or exocyclic) are not affected. Surprisingly, the reduction-elimination only takes place at A-ring 4-en-3-ones. In addition, bicyclic 4-en-3-ones are also viable substrates. Synthetic applications of steroidal 3,5-dienes are demonstrated. Our method can also lead to steroidal 3,5-dienes-3-d (>99% d-incorporation) when DCO2D and D2O are used together.

The long-range effect of substituents in the 17-position on the hydrogenation of double bond of the steroidal Δ4-3-ketones in acetic acid on a platinum catalyst is described in a series of testosterone (1) and epitestosterone (5) esters with carboxylic acids of varying alkyl chain length. The ratio 5α-to 5β-products is affected by the nature of substituents in the position 17.

Aromatase-inhibitors are used in a method of prophylaxis and/or treatment by therapy of prostatic hyperplasia. Pharmaceutical preparations suitable for such a use comprise an aromatase-inhibitor. A particularly preferred aromatase-inhibitor is, for example, testolactone.

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