Electrophilic fluorination of some steroidal α,β-unsaturated ketones

Derek H.R. Barton, John Lister-James, Robert H. Hesse, Maurice M. Pechet, Shlomo Rozen

Research output: Contribution to journalArticlepeer-review

Abstract

3β-Acetoxy-5α,6β-dichloropregn-16-en-20-one (1), on treatment with elemental fluorine at low temperature, gave the 16α,17α-difluoro-adduct (2) and, by rearrangement, the 13α,16α-difluoro-17β-methyl derivative (3). The adduct (2) was subsequently converted via a short, efficient synthetic sequence into 16α,17α-difluoroprogesterone (5). In contrast, fluorination of 21-acetoxypregna-1,4,16-triene-3,11,20-trione (6) afforded the corresponding 16α,17α-difluoro-adduct (8) in low yield. Similarly, androsta-1,4,6-triene-3,17-dione (9) was converted into the 6α,7α- difluoro-adduct (11). Fluorination with CF3OF led to an increased yield of the adduct (11) and also afforded the 6α-trifluoromethoxy- 7α-fluoro-adduct (12). Dehydrofluorination of the latter gave 6-trifluoromethoxyandrosta-1,4,6-triene-3,17-dione (13). 21-Acetoxy-11β, 17α-dihydroxypregna-1,4,6-triene-3,20-dione (5) was prepared by stepwise dehydrogenation of cortisol acetate (14). Subsequent low temperature treatment with CF3OF resulted in two major products, formulated as the adducts (17) and (18).

Original languageEnglish
Pages (from-to)1105-1110
Number of pages6
JournalJournal of the Chemical Society, Perkin Transactions 1
DOIs
StatePublished - 1982
Externally publishedYes

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