Claims
- 1. A process for the preparation of an essentially pure compound for the formula I: ##STR8## or salts thereof, wherein X stands for chlorine, bromine or iodine, which process comprises base-catalyzed epimerization of a salt of a 6.alpha.-halopenicillanic acid in aqueous solution or stereoselective reduction of a 6,6-dihalopenicillanic acid or a salt thereof with alkali metal or tetraalkylammonium borohydride or cyanoborohydride, followed by recovery of the pure compound of formula I or a salt thereof by chromatographic separation or fractionate crystallization.
- 2. A process as claimed in claim 1, wherein the epimerization is carried out at a pH of 9.0 to 9.2 and at a temperature of 30.degree. C. to 32.degree. C. for a period of 20 to 24 hours, the pH being kept constant during the course of the reaction by addition of dilute aqueous sodium or potassium hydroxide via an automatic titrator.
- 3. A process as claimed in claim 2, wherein the reduction is carried out in a polar organic solvent selected from the group consisting of dimethylformamide and dimethyl sulfoxide.
- 4. A process as claimed in claim 1, wherein the pure compound of formula I is recovered in the form of a dicyclohexylammonium salt.
Priority Claims (4)
Number |
Date |
Country |
Kind |
7917665 |
May 1979 |
GBX |
|
7930819 |
Sep 1979 |
GBX |
|
7941252 |
Nov 1979 |
GBX |
|
8006681 |
Feb 1980 |
GBX |
|
Parent Case Info
This is a continuation of application Ser. No. 564,901, filed Dec. 23, 1983, now U.S. Pat. No. 4,594,246, which is a continuation of Ser. No. 207,614 filed Nov. 17, 1980, now U.S. Pat. No. 4,446,144, which is a continuation-in-part of Ser. No. 145,880, filed May 1, 1980, now U.S. Pat. No. 4,511,512.
US Referenced Citations (3)
Continuations (2)
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Number |
Date |
Country |
Parent |
564901 |
Dec 1983 |
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Parent |
207614 |
Nov 1980 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
145880 |
May 1980 |
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