Chemical process for preparing .DELTA.9(11) dehydrosteroids
AssigneeResearch Institute for Medicine and Chemistry Inc.
InventorsDerek H. R. Barton, Robert H. Hesse
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Abstract
The Specification describes a synthetic route for the preparation of a 9,11-dehydro-3-oxygenated 17.alpha.-hydroxy-20-ketopregnane which comprises the steps (i) electrophilically fluorinating a saturated 9,11-unsubstituted 3-oxygenated-17.alpha.-(esterified hydroxy)-20-ketopregnane, (ii) dehydrofluorinating the resulting 9.alpha.-fluorosteroid, if desired after transformations elsewhere in the molecule have been effected, and (iii) cleaving the ester group at the 17.alpha.-position to generate a 17.alpha.-hydroxy group.
Claims15
A process for electrophilically fluorinating a saturated 9,11-unsubstituted-3-oxygenated-17.alpha.-(esterified hydroxy)-20-ketpregnane steriod wherein the esterified hydroxy group at the 17.alpha.-position is a nitrooxy, trifluoroacetoxy or trichloroacetoxy group, which comprises reacting said steriod and a fluorinating agent, wherein the fluorinating agent is molecular fluorine, a fluorosulphur hypofluorite or a C.sub.1-6 fluoroalkyl hypofluorite;
- substantially homogeneously dispersed in a liquid medium in the presence of a free radical inhibitor whereby formation of free fluorine radicals is suppressed and the 9.alpha.-hydrogen atom of said steriod is replaced by a fluorine atom.
A process for the preparation of a 9,11-dehydro-3-oxygenated-17.alpha.-hydroxy-20-ketopregnane which comprises the steps (i) fluorinating a saturated 9,11-unsubstituted-3-oxygenated-17.alpha.-(esterified hydroxy)-20-ketopregnane wherein the esterified hydroxy group at the 17.alpha.-position is a nitrooxy, trifluoroacetoxy or trichloroacetoxy group, which comprises reacting said steriod and a fluorinating agent, wherein the fluorinating agent is molecular fluorine, a fluorosulphur hypofluorite or a C.sub.1-6 fluoroalkyl hypofluorite;
- substantially homogeneously dispersed in a liquid medium in the presence of a free radical inhibitor, whereby formation of free fluorine radicals is suppressed and the 9.alpha.-hydrogen atom of said steriod is replaced by a fluorine atom, (ii) dehydrofluorinating the resulting 9.alpha.-fluorosteriod, and (iii) cleaving the ester group at the 17.alpha.-position to generate a 17.alpha.-hydroxy group.
Dependencies are inferred from the claim text.