0.80 g (2.7 mmol) of methyl 2-chloro-3-hydroximinomethyl-4-methylsulfonylbenzoate are dissolved in 20 ml of dimethylformamide with 0.38 g (2.9 mmol) of N-chlorosuccinimide. After stirring at room temperature for 4 hours, 0.49 g (2.9 mmol) of allylbenzene and then 0.29 g (2.9 mmol) of triethylamine are added dropwise at 0° C. After stirring at room temperature for 16 hours, the reaction mixture is concentrated in a rotary evaporator, the residue is dissolved in dichloromethane and the solution is washed with sodium bicarbonate solution and with water. After drying over magnesium sulfate and evaporating the solvent, 1.1 g (100% of theory) of methyl 2-chloro-3-(5-benzylisoxazolin-3-yl)-4-methylsulfonylbenzoate are obtained as a colorless oil.
