| 摘要 |
The process for preparing substantially pure cis a-bis-oxime isomer of the formula (Ia): R1O-N=CR2-CR3=N-OR4 {wherein R1O- and R2 are in the cis configuration with respect to the N=C bond; R1 is a C-organic radical; R2 is an organic group, which may be bound directly or via an oxygen, sulphur or nitrogen atom to the main chain; R3 is hydrogen, cyano, nitro, hydroxy, amino, halogen, alkyl, haloalkyl, alkoxy, haloalkoxy, alkylthio, alkylamino, dialkylamino or cycloalkyl and R4 are hydrogen} comprises: treating a mixture of the cis and trans isomers of the a-bis-oxime isomer of the formula Ia as defined above with a Lewis acid in an aliphatic or aromatic hydrocarbon solvent is claimed.
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