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US 2016/0244412 A1Published application
Process for the Preparation of Pyrazole Derivatives
AssigneeSRF Limited
InventorsSrikant DAKSHINAMOORTHY, Thangaselvam KAMARAJ, Sarathy IYENGAR, Arumugam NAGAPPAN, Rahul SAXENA, Rajdeep ANAND
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Abstract
The present invention provides a process for the preparation of N-alkylated fluorine-containing pyrazolecarboxylic acid derivatives of Formula I. The present invention further provides a pyrazole compound of formula IIIa.
Claims17
A process for the preparation of pyrazole compound of Formula I,
- wherein R1 represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylalkyl group which is optionally substituted;
- R2 hydrogen, alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylalkyl group which is optionally substituted, or an aryl group which is optionally substituted;
- R3 represents an alkyl group having 1 to 6 carbon atoms which is substituted by at least one halogen atom;
- and
- halogen atom selected from fluorine, chlorine, bromine and iodine
- said process comprising:
- (a) contacting a compound of Formula V with a ferric chloride to obtain a compound of Formula VI;
- R3 is defined as above;
- R5 represents an alkyl group having 1 to 6 carbon atoms;
- X is halogen atom selected from fluorine, chlorine, bromine and iodine;
- (b) contacting the compound of Formula VI with a compound of Formula VII to obtain a compound of Formula VIII;
- R2 and R3 defined as above;
- (c) contacting the compound of Formula VIII with a compound of Formula IX to obtain a compound of Formula II;
- R1 defined as above;
- (d) contacting the compound of Formula II with a compound of Formula IV and hydrochloric acid to obtain a compound of Formula III;
- and
- R1, R2 and R3 defined as above;
- R1, R2 and R3 defined as above;
- R4 represents an alkyl group having 1 to 6 carbon atoms;
- (e) contacting the compound of Formula III with water to obtain the compound of Formula I;
- wherein the compounds of Formula VI, VIII, II, and III are not isolated from the reaction mixture.
18 more elements
A process for the preparation of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid, said process comprising:
- (a) contacting 1,1,2,2-tetrafluoro-1-methoxyethane with ferric chloride on carbon pellets to obtain a first mixture;
- (b) contacting the first mixture as obtained in step (a) with 3-(dimethylamino) acrylonitrile to obtain a second mixture;
- (c) contacting monomethylhydrazine with the second mixture to obtain a third mixture comprising an aqueous layer and an organic layer;
- (d) contacting methanol and hydrochloric acid with the organic layer of step (c) to obtain hydrochloric acid salt of 3-(difluoromethyl)-1-methyl-1-H-pyrazole carboximidoate;
- (e) converting hydrochloric acid salt of methyl 3-(difluoromethyl)-1-methyl-1-H-pyrazole carboximidoateto 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid;
- and
- (f) isolating 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid from step (f).
4 more elements
A compound of Formula IIIa or its salts thereof
- wherein:
- R1 represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylalkyl group which is optionally substituted;
- R2 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylalkyl group which is optionally substituted or aryl group which is optionally substituted;
- R3 represents an alkyl group having 1 to 6 carbon atoms which is substituted by at least one halogen atom;
- halogen atom is selected from the group consisting of iodine, bromine, chlorine and fluorine;
- and
- R4 represents an alkyl group having 1 to 6 carbon atoms.
4 more elements
Dependencies are inferred from the claim text.