Process for the preparation of aromatic carboxylic acid amides

Details Process for the preparation of aromatic carboxylic acid amides Process for the preparation of aromatic carboxylic acid amides

2001-06-21

2002-08-27

Kumar, Shailendra (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Amino nitrogen containing

C564S169000, C564S183000, C546S323000

Reexamination Certificate

active

06441233

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the preparation of primary aromatic carboxamides by reacting aromatic compounds, which contain a leaving group, with carbon monoxide and a primary carboxamide, for example formamide, in the presence of a homogeneous or heterogeneous palladium catalyst and an acylation catalyst at an elevated temperature.
2. Description of the Prior Art
In J. Am. Chem. Soc. 1989, 111, pages 8742 to 8744, Y. Ben-David et al. describe the carbonylation of aryl halides in the presence of a specific Pd(0) phosphine complex, whereby depending on the nucleophile used, for example water, alkanol or secondary amine, arylcarboxylic acids, arylcarboxylates or arylcarboxamides are obtained. If dimethylformamide is used as the solvent during the reaction, it is inert and does not lead to arylcarboxylic acid dimethylamides. Under the conditions of this reaction, the production of primary amides is practically excluded and is also not mentioned.
In Tetrahedron Letters 39 (1998), pages 2835 to 2838, E. Morera et al. describe the preparation of primary aromatic carboxamides, in which an aryl iodide or triflate is carbonylated in the presence of a homogeneous Pd catalyst and hexamethyldisilazane, and afterwards the reaction mixture is worked up hydrolytically. The starting products are expensive and the necessary hydrolytic working up is uneconomical, so that this process is not suitable for use on an industrial scale.
In J. Org. Chem. 1993, 58, pages 7016 to 7021, J. Perry et al. describe the preparation of arylbenzimidazoles by reacting iodine aromatics, 1,2-phenylene and carbon monoxide in the presence of a palladium catalyst and a tertiary nitrogen base in N,N-dimethylacetamide as solvent. It is also mentioned that aromatic N,N-dimethylcarboxamides are produced as a by-product, the formation of which is explained by a decomposition of the solvent.
BRIEF SUMMARY OF THE INVENTION
It has now surprisingly been found that primary aromatic carboxamides are obtained with high selectivity and in a high yield it carbonylation is carried out by starting with aromatic compounds which contain a leaving group, with homogeneous or even heterogeneous Pd catalysts, in the presence of at least stoichiometric amounts of a primary carboxamide, for example formamide, and additionally in the presence of an acylation catalyst. Selectivity and high yields are attained even if N-alkylated carboxamides are used as the solvent.
DETAILED DESCRIPTION OF THE INVENTION
The subject matter of the invention is a process for the preparation of primary aromatic carboxamides by the carbonylation of an aromatic compound, which contains at least one leaving group, with carbon monoxide, in the presence of a homogeneous or heterogeneous Pd catalyst and at least stoichiometric amounts of an amidation agent at elevated temperatures, which is characterised in that a primary carboxamide or urethane is used as the amidation agent, and the reaction is carried out in the presence of an acylation catalyst.
The aromatic compounds in question may be hydrocarbon aromatics or hetero-aromatics. The hydrocarbon aromatics may contain, for example, 6 to 18 carbon atoms, preferably 6 to 14 carbon atoms, most preferably 6 to 10 carbon atoms. The hetero-aromatics may contain, for example 5 to 17 carbon atoms, preferably 5 to 13 carbon atoms, most preferably 4 to 9 carbon atoms, and at least one hetero atom selected from the group O, S, N and P. The aromatic compounds also include aryl- and heteroaryl-vinyls with a leaving group (especially chlorine or bromine) on a vinyl carbon atom.
Examples of hydrocarbon aromatics are benzene, pentalene, indene, indoline, naphthalene, acenaphthylene, anthracene, phenanthrene, fluorene, triphenylene, pyrene, chrysene, naphthacene, biphenyl, biphenylether, 1,4-diphenylbenzene, vinylbenzene and vinyinaphthalene. Benzene, biphenyl and naphthalene are preferred.
Examples of hetero-aromatics are thiophene, vinylthiophene, benzthiophene, furan, benzofuran, pyran, chromene, pyrrole, vinylpyrrole, imidazole, pyrazole, pyridine, vinylpyridine, bipyridyl, pyrazine, pyrimidine, pyridazine, indole, vinylindole, isoindole, 1H-indazole, quinoline, isoquinoline, phthalazine, quinoxaline, quinazoline, carbazole, acridine, phenanthroline, phenazine, thiazole, isothiazole, phenothiazine, oxazole, isooxazole, phenoxazine, pyrazole, piccoline, and lutidine.
The hydrocarbon aromatics and hetero-aromatics may be unsubstituted or substituted by at least one inert substituent, for example 1 to 3 inert substituents. Examples of substituents are C
1
-C
8
-, preferably C
1
-C
4
-alkyl, C
1
-C
8
-, preferably C
1
-C
4
-alkoxy, C
1
-C
8
-, preferably C
1
-C
4
-halogenalkyl,C
1
-C
8
-, preferably C
1
-C
4
-hydroxyalkyl, C
1
-C
8
-, preferably C
1
-C
4
-cyanoalkyl, and —CN.
Examples of alkyl substituents are methyl, ethyl, n- and isopropyl, n-, iso- and tert.-butyl, pentyl, hexyl and octyl. Examples of alkoxy substituents are methoxy, ethoxy, n- and isopropoxy, n-, iso- and tert.-butoxy, pentoxy, hexoxy and octoxy. Examples of halogenalkyl substituents are fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl, perfluoroethyl, chloroethyl, n- and iso-chloro- or -fluoropropyl, n-, iso- and tert-chlorobutyl. Examples of hydroxyalkyl substituents are hydroxymethyl, &bgr;-hydroxyethyl, n-hydroxypropyl and n-hydroxybutyl. Examples of cyanoalkyl substituents are cyanomethyl, 2-cyanoeth-1-yl and 3-cyanoprop-1-yl.
Leaving groups are known and are described in literature. Examples of leaving groups are, in particular, halides such as chloride, bromide and iodide, as well as the group R—S(O
2
)—O—, wherein R is fluorine, chlorine, halogen-methyl, phenyl, halogen-phenyl, mono-, di- or trimethylphenyl or mono-, di- or tri(halogenmethyl)phenyl. Examples are fluorosulphonyloxy, chlorosulphonyloxy, methylsulphonyloxy, trifluoromethylsulphonyloxy, nonaflate and tosylate. Other known leaving groups are aryl-substituted methoxy groups, such as diphenylmethoxy, di(methylphenyl)methoxy, trityl and tri(methylphenyl)methoxy. Preferred leaving groups are halides, especially chloride and bromide.
In the context of the invention, stoichiometric amounts of amidation agent signifies at least an equimolar amount of amidation agent, based on the aromatic compound containing leaving groups, so that there is at least one equivalent of amidation agent per leaving group. The aromatic compound preferably contains two and most preferably one leaving group, so that in this case at least two, or at least one mol of amidation agent is used per mol of aromatic compound. It may be advantageous to use a surplus of amidation agent, for example up to a molar excess of more. A high excess may be used, especially if the amidation agent serves as the solvent at the same time, for example formamide.
The presence of carbon monoxide can mean that the reaction is carried out with pure carbon monoxide, or with mixtures of carbon monoxide with an inert gas, for example nitrogen or noble gases (helium, neon, argon).
The reaction may be carried out under slightly reduced pressure, at normal pressure or preferably at high pressure. High pressure may mean, for example, up to 100 bar, preferably up to 50 bar. The reaction is most preferably carried out at a pressure of 1 to 20 bar, particularly preferably at a pressure of 1 to 10 bar.
Elevated temperature in the context of the invention can mean a temperature range of 30 to 250° C., preferably 50 to 200° C., most preferably 80 to 140° C.
Pd catalysts are known and have been described in literature many times, see for example J. Tsui in Palladium Reagants and Catalysts, John Wiley and Sons (1995). These are generally Pd(0) complexes with ligands from the group mono- and bidentate, tertiary or ditertiary amines, phosphines and arsines. Phosphines are preferred. The N, P and As atoms of the ligands may be substituted by identical or different hydrocarbon radicals having preferably 1 to 18, most preferably 1 to 12, and especially 1

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