A new practical synthesis of 1-dehydro-3-keto steroids of the A/B cis series

✍ Scribed by Y. Shimizu; H. Mitsuhashi; E. Caspi

• Book ID: 104223437
• Publisher: Elsevier Science
• Year: 1966
• Tongue: French
• Weight: 145 KB
• Volume: 7
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)90297-1

✦ Synopsis

At pesent there are no convenient procedures for the preparation of l-dehydro-3-keto-steroids of the A/B cis series. Usually for the introduction of unsaturation in conjugation with a carbonyl advantaga is taken of the direction of enolisation of the ketone. Consequently, methods employed for the synthesis of 5a-A'3-ketones me not applicable in the 5S-series2. In the A/B cis series circuitous routes requiring selective hydrogenation of 1,4-dien-3-one's3 or selective de-4 hydrobromination of 2,4-dibromo-3-one's are used. These procedures are cumbersome and unsatisfactory. We wish to present a convenient and practical m&hod for the introduction of unsaturation at C-l in 5S-3-ketones.

lbe approach chosen was based on the aeferential formylation at C-2 of A/B-cis-3-ketones 596 . Thus, lYS-hydroxy-5Sandrostan-3-one (1) was converted to the known 2-hydrollymethylene 2_ in over 9C$ yield. 'Ihe 2-hydroxymethylsne's of the A/B trans series undergo facile dshydrogenation at c-lupon treatment with dichloro dicyano quinone (D.D.Q.) and yieu the correspoaaing All;,-f-13-ketones'l.

We anticipated that a