Triethylamine → 3-Oxocyclohex-1-enyl 2-chloro-4-methylsulfonyl-3-(3a,4,5,6a-tetra-hydrofuro[3,2-d]isoxazol-3-yl)benzoate

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Reaction Steps

58.0 g (167.8 mmol) of 2-chloro-4-methylsulfonyl-3-(3a,4,5,6a-tetrahydrofuro[3,2-d]isoxazol-3-yl)-benzoate are dissolved in 600 ml of dichloromethane, and 31.94 g (251.6 mmol) of oxalyl chloride and three drops of dimethylformamide are added at room temperature. After the evolution of gas has ceased (approx. 2 hours), the mixture is refluxed for a further hour. It is subsequently concentrated, and redissolved in 300 ml of dichloromethane. At 0-5° C., a mixture of 19.5 g (173.9 mmol) of 1,3-cyclohexanedione and 17.6 g (173.9 mmol) of triethylamine in 200 ml of dichlormethane is added dropwise. The mixture is stirred for 2 hours and then washed in succession with sodium carbonate solution and sodium chloride solution, and the organic phase is then dried over magnesium sulfate. After removal of the solvent, 64.5 g (87% of theory) of crude 3-oxocyclohex-1-enyl 2-chloro-4-methyl-sulfonyl-3-(3a,4,5,6a-tetrahydrofuro[3,2-d]isoxazol-3-yl)benzoate are obtained.

Provenance & Evidence