Claims
- 1. In a process for preparing 2-bromo-6.beta.-fluoro pregna-1,4-dien-3,20-dione compounds having the formula A ##STR4## wherein X represents Br, Cl, or OQ; Y represents Br, Cl, F or H; R.sub.1 represents OQ; R.sub.2 represents OQ; R.sub.3 represents H, CH.sub.3 or .alpha.-OQ; and the groups Q, which may be the same or different from each other, represent H or acyl or the two OQ groups in 16- and 17-position or the two OQ groups in 17- and 21-position together form a cyclic ketal, cyclic acetal or cyclic alkyl orthorester, wherein at least one group OQ is a carboxylic or inorganic acid radical, by ketalizing a compound of formula I ##STR5## wherein R.sub.3 ' is hydrogen or methyl and Ac is CH.sub.3 CO under migration of the double bond into 5,6-position, epoxidizing the double bond and reacting the resulting 5.alpha.6.beta.-epoxide with hydro-fluoric acid to form a fluoro hydrin compound of formula IV ##STR6## wherein R.sub.3 ' and Ac are as defined above converting the compound of (IV) into a compound of formula VIII ##STR7## wherein R.sub.3 ' and Ac are as defined above introducing the substituents X and Y in 9- and 11-position of the compound of formula VIII and converting the OAc groups in 17- and 21-position into a group OQ to form a compound of formula A' ##STR8## wherein X, Y, R.sub.1, R.sub.2 and R.sub.3 ' are as defined above, and dehydrating a compound of formula A' wherein R.sub.3 ' is hydrogen and X, R.sub.1 and R.sub.2 each are hydroxy to form a compound of formula ##STR9## oxidizing the compound of formula XIc into the corresponding 16, 17 dihydroxy compound and converting the 16, 17 and 21 hydroxy groups therein into a group OQ to obtain a compound of formula A" ##STR10## wherein X, Y, R.sub.1 and R.sub.2 are as defined above and R.sub.3 " is OQ, wherein the improvement comprises the conversion of a compound of formula IV into a compound of formula VIII comprising the steps of
- (a) monobrominating the compound of formula IV into a corresponding 2.alpha.-bromo compound of the formula V ##STR11## wherein R.sub.3 ' and Ac are as defined above, (b) mesylating the 11-hydroxy group of the compound of formula V and acetylating the resulting 11-mesylate into a compound of formula VII ##STR12## wherein R.sub.3 ' and Ac are as defined above and MS represents CH.sub.3 SO.sub.2 --,
- (c) brominating the compound of formula VII under dehydroacetylation into a compound of formula VII bis ##STR13## wherein R.sub.3 ' Ac and MS are as defined above, and (d) dehydrobrominating the compound (VIII bis) under dehydromesylation into the compound of formula VIII.
- 2. The process as defined in claim 1 wherein in step (a) the monobromination is carried out with bromine in a buffered reaction medium.
- 3. The process as defined in claim 2 wherein the monobromination is carried out with bromine in sodium-acetate buffered dioxane.
- 4. The process as defined in claim 1 wherein in step (c) the bromination is carried out with bromine in acetic acid containing sodium or potassium acetate.
- 5. The process as defined in claim 1 wherein in step (d) the compound of formula VII bis is treated with a combination comprising a metal halide and an amide solvent.
- 6. The process as defined in claim 1 wherein the metal halide is lithium chloride, lithium bromide or mixtures thereof.
- 7. The process as defined in claim 6 wherein the combination further comprises lithium carbonate.
- 8. The process as defined in claim 6 wherein the amide solvent is selected from the group consisting of dimethylformamide, dimethylacetamide, N-formylpiperidine, and mixtures thereof.
- 9. The process as defined in claim 8 wherein the compound of formula VII bis is treated with a combination of lithium bromide and lithium carbonate in dimethylformamide.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8928/74 |
Feb 1974 |
GBX |
|
Parent Case Info
This is a division of application Ser. No. 553,124, filed Feb. 26, 1975 now U.S. Pat. No. 4,226,862.
US Referenced Citations (4)
Divisions (1)
|
Number |
Date |
Country |
Parent |
553124 |
Feb 1975 |
|