| 摘要 |
Novel, improved process for the preparation of compounds of the formula IIA in the cis form <IMAGE> where the symbols have the meanings given in claim 1, by reacting an acetoacetic ester of the formula CH3-CO-X-CH-COOR with a thionophosphoryl halide of the formula <IMAGE> in the presence of aqueous alkali metal hydroxide solution and a catalytically effective amount of a quaternary ammonium compound or quaternary phosphonium compound; the compounds can be used in crop protection and pest control.
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