D-Homo rearrangement of steroids

What is D-Homo rearrangement of steroids?

The D-Homo rearrangement of steroids was first discovered in 17β-hydroxy-20-ketosteroids, but it has since been extensively investigated in the 17α-hydroxy-20-keto series. This chemical reaction involves an acyloin rearrangement that is catalyzed by either an acid or a base, and it results in the formation of a six-membered D-ring without the loss of any carbon atoms.

D-Homo rearrangement of steroids
D-Homo rearrangement of steroids

When 17-hydroxy-20 derivatives of steroids are treated with bases or acids (including Lewis acids), they undergo D-homo rearrangement, leading to the formation of six-membered D-rings. This reaction can also occur in the absence of a carbonyl group, as long as a carbocation is formed at position 20.

The D-homo rearrangement is highly valuable in the preparation of various steroid derivatives due to its versatility and efficiency.

References

  • Ruzicka, L. and Meldahl, H.F. (1938), Über Steroide und Sexualhormone. 48. Mitteilung. Die Überführung von 17-Äthinyl-androsten-Derivaten in Pregnenon-Derivate. Herstellung des 17-Oxy-progesterons. [On steroids and sex hormones. 48. communication. The conversion of 17-ethynyl-androstene derivatives to pregnenone derivatives. Preparation of 17-oxy-progesterone] Helvetica Chimica Acta, 21: 1760-1770. https://doi.org/10.1002/hlca.193802101214
  • Ruzicka, L. and Meldahl, H.F. (1939), Über Steroide und Sexualhormone. (51. Mitteilung). Die Herstellung von Neo-pregnenolon aus Δ5-3, 17-Dioxypregnenon-(20). [On steroids and sex hormones. (51st Announcement). The preparation of neo-pregnenolone from Δ5-3, 17-dioxypregnenone-(20).] Helvetica Chimica Acta, 22: 421-424. https://doi.org/10.1002/hlca.19390220155
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