| 摘要 |
The present invention relates to a process for preparing a compound of formula (II) wherein R1 is CF3, CF2H or CFH2, and R2 and R3 are both independently C1-C6 alkyl, comprising a) reacting compounds of formula (IV), (V) and (VI) wherein R3 is as defined for the compound of formula (II), R4OM (V) wherein M is a lithium, sodium or potassium ion and R4 is C1-C6 alkyl, and (VI) wherein R1 is as defined for the compound of formula (II) and R5 is CrC6 alkyl, to form an enolate of formula (VII) wherein M is as defined for the compound of formula V and R1 and R3 are defined for the compound of formula (II), b) releasing the compound of formula (VIII) wherein R1 and R3 are as defined for the compound of formula (II), from the enolate of formula (VII) by means of an acid, and c) converting the compound of formula (VIII), in the presence of the salt formed from cation M and the anion of the acid in step b), to a compound of formula (II). |
