Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2000-01-19
2003-01-07
Berch, Mark L (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
active
06504027
ABSTRACT:
BACKGROUND OF THE INVENTION
In the past purification and isolation of the compound of formulae I and II were achieved via a combination of several operations: extractions using solvents such as dichloromethane to remove residual organic solvents, chromatography using hydrophobic resins, nanofiltration for concentration of the process stream followed by crystallization of the pure drug. Several of these operations require high capital expenditure. In addition, the time-cycle of such a process is relatively long compromising the quality of the carbapenem product.
The object of the present invention is to teach a much simplified isolation protocol of the compound of formulae I and II via extractions with an alcohol with or without containing an appropriate ion-pairing reagent which concomitantly concentrates the carbapenem compounds followed by a direct crystallization of the product. The present invention is a more practical, efficient, safer and cost effective process because it eliminates the time consuming (and capital intensive) column purification and nanofiltration steps which can compromise the quality of the carbapenem compound due to degradation.
These and other objects will be apparent from the teachings contained herein.
SUMMARY OF THE INVENTION
A process for the direct crystallization of a compound of the formula I:
or a pharmaceutically acceptable salt thereof, is disclosed, wherein R
1
and R
2
represent H, C
1-10
alkyl, aryl or heteroaryl, or substituted C
1-10
alkyl, aryl or heteroaryl and X
+
represents a charge balancing group, comprising
extracting a solution containing a crude compound of formula I or Ia:
or a pharmaceutically acceptable salt thereof, wherein each X+ is a charge balancing group, and R1 and R2 are as described above with a C4-10 alcohol, collecting and crystallizing the resulting aqueous phase to produce a crystalline compound of formula I.
DETAILED DESCRIPTION OF THE INVENTION
Carbapenems can be prepared by coupling the, appropriate sidechain to a protected enolphosphate (3). In this reaction a base and solvent are used. The resulting crude product can then be deprotected to give the desired carbapenem in its crude form. In order to isolate this product in pure form via crystallization sideproducts and solvents need to be removed and the concentration of the product increased. In the past this has been typically achieved via a combination of extraction, column chromatography and nanofiltration.
It has now been discovered that the column chromatography and nanofiltration operations can be eliminated when the extraction is carried out with an appropriate alcohol. A preferred extraction is carried out with the appropriate alcohol in the presence of an ion-pairing reagent. The process described herein allows a direct crystallization of carbapenem compounds after this type of extraction. The process eliminates the column purification step and replaces the nanofiltration step for concentration of the carbapenem compound in preparation for the crystallization step.
The invention is described herein in detail using the terms defined below unless otherwise specified.
The term “alkyl” refers to a monovalent alkane (hydrocarbon) derived radical containing from 1 to 15 carbon atoms unless otherwise defined. It may be straight or branched, and when of sufficient size, e.g., C
3115
may be cyclic. Preferred straight or branched alkyl groups include methyl, ethyl, propyl, isopropyl, butyl and t-butyl. Preferred cycloalkyl groups include cyclopropyl, cyclopentyl and cyclohexyl.
Alkyl also includes an alkyl group substituted with a cycloalkyl group, such as cyclopropylmethyl.
Alkyl also includes a straight or branched alkyl group which contains or is interrupted by a cycloalkylene portion. Examples include the following:
wherein: x′ and y′=from 0-10; and w and z=from 0-9.
The alkylene and monovalent alkyl portion(s) of the alkyl group can be attached at any available point of attachment to the cycloalkylene portion.
When substituted alkyl is present, this refers to a straight, branched or cyclic alkyl group as defined above, substituted with 1-3 groups as defined with respect to each variable.
Heteroalkyl means an alkyl group containing from 2-15 carbon atoms and being interrupted by from 1-4 heteroatoms selected from O, S and N.
The term “alkenyl” refers to a hydrocarbon radical straight, branched or cyclic containing from 2 to 15 carbon atoms and at least one carbon to carbon double bond. Preferably one carbon to carbon double bond is present, and up to four non-aromatic (non-resonating) carbon-carbon double bonds may be present. Preferred alkenyl groups include ethenyl, propenyl, butenyl and cyclohexenyl. As described above with respect to alkyl, the straight, branched or cyclic portion of the alkenyl group may contain double bonds and may be substituted when a substituted alkenyl group is provided.
The term “alkynyl” refers to a hydrocarbon radical straight, branched or cyclic, containing from 2 to 15 carbon atoms and at least one carbon to carbon triple bond. Up to three carbon-carbon triple bonds may be present. Preferred alkynyl groups include ethynyl, propynyl and butynyl. As described above with respect to alkyl, the straight, branched or cyclic portion of the alkynyl group may contain triple bonds and may be substituted when a substituted alkynyl group is provided.
Aryl refers to aromatic rings e.g., phenyl, substituted phenyl and like groups as well as rings which are fused, e.g., naphthyl and the like. Aryl thus contains at least one ring having at least 6 atoms, with up to two such rings being present, containing up to 10 atoms therein, with alternating (resonating) double bonds between adjacent carbon atoms. The preferred aryl groups are phenyl and naphthyl. Aryl groups may likewise be substituted as defined below. Preferred substituted aryls include phenyl and naphthyl substituted with one to three groups, such as selected from halo, alkyl and trifluoromethyl.
The term “heteroaryl” refers to a monocyclic aromatic hydrocarbon group having 5 or 6 ring atoms, or a bicyclic aromatic group having 8 to 10 atoms, containing at least one heteroatom, O, S or N, in which a carbon or nitrogen atom is the point of attachment, and in which one additional carbon atom is optionally replaced by a heteroatom selected from O or S, and in which from 1 to 3 additional carbon atoms are optionally replaced by nitrogen heteroatoms. The heteroaryl group is optionally substituted with up to three groups.
Heteroaryl includes aromatic and partially aromatic groups which contain one or more heteroatoms. Examples of this type are thiophene, purine, imidazopyridine, pyridine, oxazole, thiazole, oxazine, pyrazole, tetrazole, imidazole, pyridine, pyrimidine, pyrazine and triazine. Examples of partially aromatic groups are tetrahydroimidazo[4,5-c]pyridine, phthalidyl and saccharinyl, as defined below.
Substituted alkyl, aryl and heteroaryl, and the substituted portions of aralkyl, aralkoxy, heteroaralkyl, heteroaralkoxy and like groups are substituted with from 1-3 groups selected from the group consisting of: halo, hydroxy, cyano, acyl, acylamino, aralkoxy, alkylsulfonyl, arylsulfonyl, alkylsulfonylamino, arylsulfonylamino, alkylaminocarbonyl, alkyl, alkoxy, aryl, aryloxy, aralkoxy, amino, alkylamino, dialkylamino, carboxy and sulfonylamino.
The terms “heterocycloalkyl” and “heterocyclyl” refer to a cycloalkyl group (nonaromatic) in which one of the carbon atoms in the ring is replaced by a heteroatom selected from O, S(O)y or N, and in which up to three additional carbon atoms may be replaced by said heteroatoms. When three heteroatoms are present in the heterocycle, they are not all linked together.
Examples of heterocyclyls are piperidinyl, morpholinyl, azetidinyl, pyrrolidinyl, tetrahydrofuranyl, imidazolinyl, piperazinyl, pyrolidin-2-one, piperidin-2-one and the like.
Acyl as used herein refers to —C(O)C
1-6
alkyl and —C(O)-aryl.
Acylamino refers to the group —NHC(O)C
1-6
alkyl and —NHC(O)aryl.
Aralkoxy refers to th
Brands Karel M. J.
Houghton Peter
Skerlj Renato T.
Williams John M.
Ayler Sylvia A.
Berch Mark L
Daniel Mark R.
Merck & Co. , Inc.
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