Dibromohydantoin → 9alpha-Bromo-11-hydroxypregna-1,4-diene

Participants

Reaction Steps

The pregna-1,4,9(11)-trienes represented by formula (A) above are converted to various intermediates by means known in the art. For example they are treated with chlorine according to the process of U.S. Pat. No. 3,009,933 to give the corresponding 9α,11β-dichloropregna-1,4-diene ##STR15## The 9α-fluoro-11β-hydroxy compound is prepared by reacting the appropriate pregna-1,4,9(11) triene with dibromohydantoin to form the 9α-bromo-11-hydroxypregna-1,4-diene which in turn is reacted with sodium hydroxide to give the corresponding 9β,11β-epoxide. This epoxide is then treated with a hydrogen fluoride/urea complex according to the process set forth in U.S. Pat. No. 3,211,758 to Tarkoey to give the 9α-fluoro-11β-hydroxy compound. The 9α-chloro-11β-hydroxy compound is prepared by reacting the 9β,11β-epoxide with hydrogen chloride in methylene chloride or by reacting the Δ9,(11) steroid with dichlorohydrantoin. An 11β-hydroxy (9-unsubstituted) steroid is readily prepared by methods well known in the art such as employing Cunninghamella blakesleena, Cunninghamella bainieri, Curvularia lunata or other suitable micro-organisms in a suitable medium which selectively affords the desired 11-hydroxy steroid.

Provenance & Evidence