- Preparative method for carboxylic acids
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A preparative method for carboxylic acids is disclosed in the present invention. The method is characterized in that: compounds (II) are reacted in the presence of hydrogen peroxide and base to produce target products (I), as represented by the following reaction scheme: wherein R1 is aryl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, benzothienyl, benzofuranyl, quinolinyl, isoquinolinyl, thiadiazolyl, C1-6 alkyl, C3-6 cycloalkyl, C2-6 alkenyl, C2-6 alkynyl and hydrogen; R2 is alkoxycarbonyl, alkylaminocarbonyl, aminocarbonyl, alkylthiolcarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, aldehyde, carboxyl, nitro, alkyl and hydrogen; R3 is alkoxycarbonyl, alkyl amido carbonyl, aminocarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, carboxyl and nitro. The present invention has the following main benefits: cheap and readily available starting materials, safe processes, high yield, good quality, which facilitates industrial production.
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- PROCESS FOR THE PREPARATION OF 4,5,6-TRICHLOROPICOLINIC ACID
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4,5,6-Trichloropicolinic acid is prepared by selectively dechlonnating 3,4,5,6- tetrachloropicolinic acid with zinc and a catalyst prepared from a nickel compound and a bidentate ligand in a polar solvent. A process for the preparation of 4,5,6-trichloro-picolinic acid by the regioselective reductive dechlorination of 3,4,5,6-tetrachloropicolinic acid is provided. More particularly, the process is described for the preparation of 4,5,6-trichloropicolinic acid (Formula I) which comprises selectively dechlonnating 3,4,5,6-tetrachloropicolinic acid (Formula II) with zinc and a catalyst prepared from a nickel compound and a bidentate ligand in a polar solvent.
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- NOVEL COMPOSITIONS AND METHODS OF USE
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Described herein are novel enzyme inhibitors. In some embodiments the enzyme inhibitors are integrase inhibitors, particularly HIV integrase inhibitors. Also described herein are compositions containing them and methods of using them. Thus, the compounds and compositions described herein are useful for the in vitro and in vivo inhibition of HIV integrase as a method of treating or preventing HIV, AIDS or related disorders.
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Page/Page column 111-112
(2009/09/04)
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- Regiochemical flexibility: The optional functionalization of 2,3,5-trihalopyridines at the 4- or 6-position
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A deprotonation study was performed using 2,3,5-trichloropyridine, 3,5-dichloro-2-fluoropyridine and 5-chloro-2,3-difluoropyridine as the substrates. Upon reaction with lithium diisopropylamide (LDA), deprotonation occurred exclusively at the 4-position. Subsequent carboxylation and iodination led to the acids 1 and 4-iodopyridines 2. The exposure of the latter compounds to lithium 2,2,6,6-tetramethylpiperidide (LITMP) caused deprotonation and immediately ensuing iodine migration. The intermediates were trapped with dry ice to afford the carboxylic acids 3. Upon neutralization, the 6-iodopyridines 4 were obtained. These compounds readily exchanged the heavy halogen for metal when treated with isopropylmagnesium chloride. In this way, functional groups could be selectively introduced in the 6-position. Employing carbon dioxide routinely as the model electrophile, trihalopyridinecarboxylic acids were formed which, all unknown so far, should provide valuable new building blocks for pharmaceutical research. Moreover, the selective nucleophilic displacement of the halogen at the 2-position could give rise to an immense variety of new structures.
- Bobbio, Carla,Schlosser, Manfred
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p. 4533 - 4536
(2007/10/03)
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- Preparation of 3,5,6-trichloropicolinic acid
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3,5,6-Trichloropicolinic acid is prepared in a process which comprises A. reacting by contacting tetrachloropicolinic acid, hydrazine and an alkali reaction medium in water; B. reacting by contacting the thus formed 3,5,6-trichloro-4-hydrazinopicolinic acid intermediate with an alkali metal hydroxide and an alkaline hypochlorite solution; and C. acidifying the reaction mixture with a mineral acid and recovering the desired 3,5,6-trichloropicolinic acid product.
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