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US 9,957,256 B2Granted
Process for the preparation of 5-fluoro-1H-pyrazoles starting from hexafluoropropene
AssigneeBayer CropScience AG
InventorsSergii Pazenok, Norbert Lui, Christian Funke
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Abstract
A new process for the preparation of 5-fluoro-1H-pyrazoles of the general formula (I) as described herein and further reactions with this compound.
Claims17
A process for synthesis of 5-fluoro-1H-pyrazoles of formula (I)
- wherein
- R1 represents optionally halogenated (C1-C4)alkyl or optionally halogenated cyclopropyl;
- comprising
- preparing perfluoro-4-methyl-2-pentene (intermediate (2)) in a Step 1
- by reacting hexafluoropropene (compound (1))
- in the presence of a catalyst to form its dimer perfluoro-4-methyl-2-pentene;
- and
- preparing perfluoro-2-methyl-2-pentene (intermediate (3)) in a Step 2
- by isomerizing perfluoro-4-methyl-2-pentene into perfluoro-2-methyl-2-pentene;
- and
- preparing perfluoro-2-methyl-2-penten-)3-enolate (intermediate (4)) in a Step 3
- wherein Cat+ refers to a positively charged organic ion, alkaline metal cation or alkaline earth metal cation,
- by reacting perfluoro-2-methyl-2-pentene with water and a base;
- and
- preparing compound of formula (I) in a Step 4 by reacting intermediate (4) in Step 4 with a hydrazine of formula (5)
- R1-NH—NH2 (5)
- wherein
- R1 is optionally halogenated C1-C4-alkyl or optionally halogenated cyclopropyl.
15 more elements
Dependencies are inferred from the claim text.