1-Chloro-3-(1,2-dibromoethyl)benzene was prepared by two-step bromination reaction with m-chloroethylbenzene as the starting material, and then it was eliminated under the condition of base and phase transfer catalyst, and then the intermediate A was prepared by Grignard reaction and chlorination of chlorosulfoxide with a total of 5-steps reaction, and the intermediate A was prepared by the cyclo-combination of diethyl phthalate as the raw material, sodium ethanol as the base and ethyl butyrate, and then it was prepared by the cyclo-combination of 2-ethyl-1H-indene-1,3(2H)-dione ( Intermediate B), intermediates A and B substitution reaction and then by epoxidation to produce indenone. This method has the following drawbacks: stepwise bromination reaction leads to the increase of reaction danger, the generated hydrobromic acid is more corrosive, the elimination reaction is easy to produce benzyl elimination of by-products, the halogenated olefin is relatively less reactive and the preparation of Grignard's reagent needs to be strictly controlled by the reaction conditions, the chlorination reaction needs to be stimulating sulfoxide chloride, and so on.
