Method for preparing pyridine-2,3-dicarboxylic acid esters
AssigneeLonza Ltd.
InventorsYves Bessard, Gerhard Stucky, Jean-Paul Roduit
Life of this patent
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Abstract
A method for preparing pyridine-2,3-dicarboxylic acid esters of the general formula: wherein R is C1-6-alkyl, C3-6-cycloalkyl, aryl or arylalkyl, and R1 to R3, independently of one another, represent hydrogen, C1-6-alkyl, fluorinated C1-6-alkyl, C1-6-alkoxy, (C1-6-alkoxy)-C1-6-alkyl or (C1-6-alkoxy)carbonyl. These esters are obtained from the corresponding 2,3-dichloropyridine, the corresponding alcohol ROH and carbon monoxide in the presence of a palladium-diphosphine complex and a weak base. Pyridine-2,3-dicarboxylic acid esters are herbicides or intermediates for the preparation of herbicides.
Claims28
A method for preparing a pyridine-2,3-dicarboxylic acid ester of formula:
- wherein R is C1-6-alkyl, C3-6-cycloalkyl, aryl or arylalkyl, and R1 to R3, independently of one another, is hydrogen, C1-6-alkyl, fluorinated C1-6-alkyl, C1-6-alkoxy, (C1-6-alkoxy)-C1-6-alkyl or (C1-6-alkoxy)carbonyl, comprising reacting a 2,3-dichloropyridine of formula:
- wherein R1 and R3 are each defined as above, with carbon monoxide and an alcohol of formula:
- R—OH
- wherein R is defined as above, in the presence of (i) a catalytically active complex of palladium with a diphosphine of formula:
- R4R5P—Q—PR6R7
- wherein R4 to R7, independently of one another, is phenyl, substituted phenyl, C1-6-alkyl or C3-6-cycloalkyl, and Q is a 1,1′-ferrocenediyl group, and (ii) a base that is selected from the group consisting of alkali metal salts of lower carboxylic acids, alkaline earth metal salts of lower carboxylic acids, alkali metal hydrogen carbonates, alkaline earth metal hydrogen carbonates, alkali metal (di)hydrogen phosphates and alkaline earth metal (di)hydrogen phosphates.
A method for preparing a pyridine-2,3-dicarboxylic acid ester of formula:
- wherein R is C1-6-alkyl, C3-6-cycloalkyl, aryl or aylalkyl, and R1 to R3, independently of one another, is hydrogen, C1-6-alkyl, fluorinated C1-6-alkyl, C1-6-alkoxy, (C1-6-alkoxy)-C1-6-alkyl or (C1-6-alkoxy)carbonyl, comprising reacting a 2,3-dichloropyridine of formula:
- wherein R1 to R3 are each as defined above, with carbon monoxide and an alcohol of formula:
- R—OH
- wherein R is defined as above, in the presence of (I) a catalytically active complex of palladium with a diphosphine of formula:
- R4R5P—Q—PR6R7
- wherein R4 to R7, independently of one another, is phenyl, substituted phenyl, C1-6-alkyl or C3-6-cycloalkyl, and Q is a group of the formula —[CH2]n—, wherein n is 3 or 4, and (ii) a base that is selected from the group consisting of alkali metal salts of lower carboxylic acids, alkaline earth metal salts of lower carboxylic acids, alkali metal hydrogen carbonates, alkaline earth metal hydrogen carbonates, alkali metal (di)hydrogen phosphates and alkaline earth metal (di)hydrogen phosphates.
Dependencies are inferred from the claim text.