METHOD OF SYNTHESIS OF 4-METHYL-3-[2-(N-PROPYL- -AMINO)PROPIONYLAMINO]THIOPHENE-2-CARBOXYLIC ACID METHYL ESTER HYDROCHLORIDE Russian patent published in 2002 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to a method of synthesis of 4-methyl-3-[2-(n-propylamino)propionylamino] -thiophene-2-carboxylic acid methyl ester hydrochloride which the best topical anesthetic agent now - articaine hydrochloride using in stomatological practice and surgery. Acylation process is carried out in a mixture of methylene chloride with water, obtained reaction mass is separated for an aqueous and an organic layer - a solution of intermediate product in methylene chloride. Solvent is distilled off and residue containing an intermediate product is subjected for interaction with a double excess of n-propylamine in dimethylformamide or acetonitrile medium at 40-50 C. Solvent is distilled off and a base is separated from hydrochloric solution followed by treatment with activated carbon and precipitation with alkaline agent and the following preparing hydrochloride by conventional method. This method ensures to obtain articaine hydrochloride without the special isolation of intermediate product and without the use of high-vacuum distillation of 4-methyl-3-[2-(n-propylamino)propionylamino] thiophene-2-carboxylic acid methyl ester. EFFECT: improved and simplified method of synthesis and preparing. 1 ex