Preparation method of isoxaflutole key intermediate

The invention relates to the field of pesticide chemistry, in particular to a preparation method of an isoxaflutole key intermediate. The preparation method comprises the steps of under the protection of inert gas, dissolving 1-(2-(methylthio)-4-(trifluoromethyl) phenyl) ethanone and cyclopropane formonitrile in an organic solvent, adding strong base, carrying out heat treatment reaction on the mixture, adding acidizing fluid to adjust the pH value to be neutral after the reaction is completed, separating out a water phase, and concentrating an organic phase to obtain an intermediate I; and dissolving the intermediate I in an organic solvent, adding water and strong acid, carrying out a heat treatment reaction, separating a water phase after the reaction is completed, and concentrating an organic phase to obtain the 1-cyclopropyl-3-(2-(methylthio)-4-(trifluoromethyl) phenyl) propyl-1, 3-diketone. The preparation method of the isoxaflutole key intermediate provided by the invention has the advantages of mild r