Process for preparing alkyl 2-alkoxymethylene-4,4-difluoro-3-oxobutyrates
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Abstract
A process for preparing alkyl 2-alkoxymethylene-4,4-difluoro-3-oxobutyrates (VI)
where R is methyl or ethyl,
from crude reaction mixtures of alkyl 4,4-difluoroacetoacetates (I)
by
- a) reacting
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- where M is a sodium or potassium ion, and
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- without additional solvent to form an enolate (V)
- b) releasing the corresponding alkyl 4,4-difluoroacetoacetate (I) from the enolate (V) by means of acid,
- c) removing the salt formed from cation M and acid anion as a solid and
- d) converting (I), without isolation from the crude reaction mixture, to the alkyl 2-alkoxymethylene-4,4-difluoro-3-oxobutyrate (VI),
and the use of (VI) for preparing 1-methyl-3-difluoromethyl-pyrazol-3-ylcarboxyates VII
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Citations
21 Claims
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1-10. -10. (canceled)
- 11. A process for preparing an alkyl 2-alkoxymethylene-4,4-difluoro-3-oxobutyrate of the formula (VI)
Specification