Synthesis method of spirodiclofen

The invention discloses a synthesis method of spirodiclofen. The synthesis method comprises the following steps: enabling 3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4,5]-deca-3-ene4-ol and 2-2-dimethylbutyl chloride serving as raw materials to have a reaction in the presence of triethylamine serving as a catalyst in a non-proton type organic solvent; after the reaction is over, regulating the pH value of the reaction liquid to 10-11 with alkali liquid, standing for layering to obtain an aqueous phase and an organic phase, and separating out the aqueous phase as the alkali liquid in next batch of synthesis; washing the organic phase with water, drying with anhydrous sodium sulfate, heating and performing atmospheric distillation to remove a mixed solvent containing triethylamine and the non-proton type organic solvent, so as to obtain a solid product, wherein the removed mixed solvent is used as the catalyst and non-proton type organic solvent in next batch of synthesis; and recrystallizing the obtained solid product to obtain the product spirodiclofen. Triethylamine and dichloromethane are recovered together and directly utilized in next batch of synthesis, so that the production cost is lowered, and the emission of high-concentration brine waste water can be reduced.