DD283134A5 - PROCESS FOR PREPARING PYRAZOLIN CARBOXYLIC ACID ESTERS - Google Patents

Abstract

The invention relates to a process for the preparation of Pyrazolincarbonsaeureestern. The aim of the invention is to develop a process for the production of *. According to the invention, the pyrazole carboxylic acid esters of the general formula III in which R is an alkyl radical and R 2 is an optionally substituted phenyl radical can be prepared by reacting the substituted thiazolidinylidenecyanoacetic acid esters of the general formula I in which R is as defined above and R 1 is an optionally substituted phenyl radical, with substituted hydrazines of the general formula II in which R 2 has the above meaning. These Pyrazolincarbonsaeureester can be used as organic intermediates for further syntheses. They are particularly suitable for the preparation of condensed heterocyclic compounds {pyrazoline carboxylic acid ester; thioether; carboxylic acid hydrazides; arylhydrazines; thiazolidinones; cyanoacetic}

Description

ROOC

^C ~ ^C

R ¹ NC = O

-CH

2R ² NHNH,

ROOC-C = CS-CH ₂ -CONHNHr ²

HN = C NH

Claims (1)

Invention claim: A process for the preparation of pyrazolinecarboxylic acid esters of the general formula III in which R is an alkyl radical and R ^{2 is} an optionally substituted phenyl radical, characterized in that substituted thiazolidinylidenecyanoacetic acid esters of the general formula I in which R is as defined above and R ^{1 is} an optionally substituted phenyl radical is reacted with substituted hydrazines of the general formula II in which R ^{2 has} the above meaning, in the presence of acetic acid. For this 1 page formulas Field of application of the invention The invention relates to a process for the preparation of 1-aryl-3- (2-aryl-hydrazinocarbonylmethylthio) -5-imino-A ³ -pyrazolin-4-cerbonsäure-alkyl esters. These pyrazoline carboxylic acid esters can be used as organic intermediates for further syntheses. They are particularly suitable for the preparation of condensed heterocyclic compounds. Characteristic of the known state of the art 1 • Aryl-3- (2-aryl-hydrazinocarbonylmethylthio) -5-imino-Ä ³ -pyrazoline-4-carboxylic acid-8-kylester are not yet known. Object of the invention The aim of the invention is the development of a process for the production of potentially biologically active compounds. Explanation of the essence of the invention The object of the invention is to develop a process for the preparation of 1-aryl-3- (2-aryl-hydrazinocarbonylmethylthio) -5-imino-A ³ -pyrazoline-4-carboxylic acid alkyl esters on the basis of thiazolidinylidenecyanoacetic acid esters. According to the invention, the pyrazolinecarboxylic esters of general formula III in which R is an alkyl radical and R ^{2 is} an optionally substituted phenyl radical can be prepared by reacting the substituted thiazolidinylidenecyanoacetic acid esters of general formula I where R is as defined above and R ^{1 is} an optionally substituted phenyl radical is prepared with substituted hydrazine ™ of the general formula II in which R ^{2 has} the above meaning, be prepared in the presence of acetic acid. The reactions are carried out in protic organic solvents, preferably in alcohols. It is expedient to react the thiazolidinylidenecyanoacetic esters I and the substituted hydrazines II in a molar ratio of 1: 2, as corresponds to the stoichiometry of the reaction equation. The reaction temperatures are at the boiling points of the solvents used. Depending on these boiling temperatures, the reaction times range from 2 to 12 hours. After cooling the reaction mixtures to 20 ⁰ C crystallize the reaction products. They can be recrystallized after filtration and washing with alcohols from organic solvents for further purification. Ausführungsbolsplele
Embodiment 1 5-Imino-1-phenyl-J- (2-phenyl-hydrazinocarbonylmethylthio) -A ³ -pyrazoline-4-carboxylic acid methyl ester A mixture of 0.01 mol / mol of 4-oxo-3-phenyl-thiazolidin-2-ylidene cyanoacetic acid methyl ester, 0.02 mol / mol phenylhydrazine, 0.005 mol / mol acetic acid and 20 ml ethanol is refluxed for 6 hours. The reaction mixture is then allowed to cool to 20 ° C, the precipitate is filtered off, washed with ethanol, the filtrate is concentrated in vacuo, allowed to crystallize again and receives further product. The crude products are recrystallized from ethanol. Yield: 80% of theory. Melting point: 168-171 "C Ausführungsbeisple! 2 Ethyl 5-lmino-1-phenyl-3- (2-phenyl-hydrazinocarbonylmethylthio) -A ³ -pyrazoline-4-carboxylate 0.01 mol / mo! 4-Oxo-3-phenyl-thiazolidin-2-ylidene-cyanoacetic acid ethyl ester and 0.02 mol / mol phenylhydrazine are reacted, as under Ausführungsbeispie! 1 described. Yield: 75% of theory. Melting point: 160-162 ⁰ C Embodiment 3 Ethyl 5-lmino-1-phenyl-3- (2-phenyl-hydrazinocarbonylmethylthio) -A ³ -pyrazoline-4-carboxylate 0.01 mol / mol of S-ip-methoxy-phenyD ^ -oxothiazolidine-1-ylidene-cyanoacetic acid ethyl ester is reacted with 0.02 mol / mol of phenylhydrazine as described in Example 1. Yield: 80% of theory. Melting point: 160-162 ⁰ C