Triethylamine → 2-Methyl-6-trifluoromethylnicotinic acid 4-oxobicyclo[3.2.1]oct-2-en-2-yl ester

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Reaction Steps

The 2-methyl-6-trifluoromethyl-nicotinic acid (2.0 g, 0.0098 mol) obtained is dissolved in 20 ml of oxalyl chloride. Three drops of dimethylformamide are added and the mixture is refluxed for 1 hour. The mixture is then concentrated using a rotary evaporator and the residue (2-methyl-6-trifluoromethyl-nicotinoyl chloride) is taken up in 30 ml of methylene chloride. At 0° C., 2.7 ml (0.0196 mol) of triethylamine and 0.12 g (0.00098 mol) of dimethylaminopyridine are added, and then 1.49 g (0.0108 mol) of bicyclo[3.2.1]oct-2,4-dione, dissolved in 20 ml of methylene chloride, are added dropwise. After 3 hours at 22° C., the reaction mixture is extracted by shaking with 2N hydrochloric acid. The separated methylene chloride phase is washed with water and then extracted by shaking with 10% aqueous sodium bicarbonate solution, dried over sodium sulfate and concentrated by evaporation. 3.18 g (100% of theory) of 2-methyl-6-trifluoromethyl-nicotinic acid 4-oxo-bicyclo[3.2.1]oct-2-en-2-yl ester are obtained in the form of an oil, which can be used further without purification.

Provenance & Evidence