- NEW METHOD FOR THE PREPARATION OF THE ANTI-ULCER COMPOUNDS OMEPRAZOLE, LANSOPRAZOLE AND PANTOPRAZOLE
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The present invention describes a new process for the preparation of omeprazole, lansoprazole and pantoprazole of formula (XXI), (XXXIII), and which involves the formation of pyridines N-oxide using a rhenium compound as a catralyst, followed by nitration of the 4-position with nitric acid fuming in presence of a claycop. The chlorination of the 2-methyl group of pyridine was achieved by using the POCI3/Et3N, which allowed the preparation of the derivates 2-chloromethylpyridines in only one step. These derivates reacted with the mercaptobenzimidazolic derivatives in presence of ultra-sonic radiation, giving the thioethers. The oxidation of these thioethers was done with several oxidizing agents and the required anti-ulcer compounds were obtained after the substitution of nitro group by the corresponding OR groups.
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(2010/02/07)
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