Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Patent
1997-06-19
1999-03-16
Barts, Samuel
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
544317, 544327, 5482626, C07D25102
Patent
active
058832530
DESCRIPTION:
BRIEF SUMMARY
This is a 371 application of PCT/EP95/04865 filed Dec. 11, 1995.
The invention relates to a process for the preparation of aromatic ortho-sulfocarboxylic acids by diazotisation and subsequent palladium-catalysed carbonylation of aromatic aminosulfonic acids. The process is particularly suitable for the preparation of ortho-sulfobenzoic acids. The invention also relates to a process for the preparation of sulfonylureas using the ortho-sulfocarboxylic acids as intermediates.
Ortho-sulfobenzoic acids are important intermediates for the preparation of saccharin derivatives which can be used as pharmaceutical products. WO 90/13549 proposes, for example, the use of substituted saccharin derivatives as enzyme inhibitors for the treatment of degenerative diseases.
Saccharin has also long been used as sweetener, and its preparation and properties are described, inter alia, in Ullmanns Enzyklopadie der technischen Chemie, Vol. 22, 353-357, 1982.
Ortho-sulfobenzoic acids are also valuable intermediates for the preparation of acid dyes for textiles, in particular of wool and polyamide dyes.
Another important field in which ortho-sulfobenzoic acids find utility as intermediates is that of the agrochemicals, in particular herbicides of the sulfonylurea type disclosed, inter alia, in EP-A-0496 701.
Ortho-sulfobenzoic acids at the present time are prepared mainly by oxidation of the corresponding toluenesulfonic acids, using bichromate in concentrated sulfuric acid or potassium permanganate for the oxidation. This is described, inter alia, in Ullmanns Enzyklopadie der technischen Chemie, Vol. 22, 356,1982. Beilstein Vol. 11, 414 (1928), for example, specifically describes the oxidation of 4-methoxy-1 -methylbenzene-2-sulfonic acid with KMnO.sub.4.
The reaction conditions are drastic and have serious drawbacks with respect to ecology and industrial hygiene, such as heavy metal pollutants which have to be disposed of, as well as the use of concentrated acids, so that special protective measures and methods of disposal are required.
In particular, these processes are unsuitable for the economic preparation of substituted ortho-sulfocarboxylic acids, since a great number of by-products are formed under such reaction conditions, so that the reaction mixture is often obtained in the form of a dark oil or even in the form of tar. Furthermore, the processing of manganese- or chromium-containing waste acid poses another problem which can only be solved using elaborate technology, e.g. electrolysis for the recovery of chromium oxide.
A further process for the preparation of ortho-sulfobenzoic acids, the so-called Maumee process, is described, inter alia, in WO 90/13549. In this process, the sulfite is first prepared from diazotised anthranilic acid in a Sandmeier reaction with SO.sub.2 and then oxidised with Cl.sub.2. This, too, is a multistep reaction with educts which are difficult to handle and yields which are too low.
In J. Org. Chem., 45, 2365 (1980) and 46, 4413 (1981), Matsuda et al. describe the palladium-catalysed carbonylation of diazonium salts. The reaction is carried out in the presence of a palladium acetate catalyst in an aprotic solvent, e.g. acetonitrile, resulting in the case of the 4-methoxy diazonium salt, used in the form of its tetrafluoroborate, in a 58% yield of 4-methoxy benzoic acid. If protic solvents, e.g. alcohols, are used, a substantial loss in selectivity is observed and, inter alia, ester and free acid are obtained. The reaction is carried out in the presence of acetate, giving first a mixed anhydride which is then hydrolysed to the free acid. At higher reaction temperatures formation of tar is often observed, which renders the catalyst ineffective and results in a considerably reduced yield.
The carbonylation of aromatic ortho-sulfobenzodiazonium salts to the corresponding aromatic ortho-sulfocarboxylic acids is so far not known.
Surprisingly, it has now been found that the internal salt which forms during the diazotisation of aromatic o-aminosulfonic acids is very stable so that no additional ani
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Journal of Organic Chemistry, vol. 45, No. 12, 1980 pp. 2365-2368.
Beyer-Walter, Lehrbuch d. org. Chemie 21: pp. 551, 553 & 559 (1988).
Drugs of the Future 18 (8): pp. 717-720 (1993).
Barry, J., et al, "Solid-Liquid Phase-Transfer Catalysis without Added Solvent, A Simple, Efficient, and Inexpensive . . . " Synthesis, Jan.: pp. 40-45 (1985).
Brunisholz Jean
Muller Manfred
Siegrist Urs
Barts Samuel
Borovian Joseph
Novartis AG
Teoli, Jr. William A.
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