Pyridine → 8-Methyl-2-[2-methyl-6-(trifluoromethyl)-3-pyridinyl]-4H-3,1-benzoxazine

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Reaction Steps

A mixture of the 6-methyl isatoic anhydride (3.92 g, 22.1 mmol) and the acid chloride from Step A (5.45 g, 24.3 mmol) was heated at reflux in pyridine for 16 hours. The dark brown solution was cooled to room temperature and the solvent was removed under reduced pressure. Excess pyridine was removed by azeotrope with toluene. Ether was added and the resulting brown solid was removed by filtration. The solid was taken up in a mixture of aqueous sodium bicarbonate and chloroform, the chloroform extracts were dried over magnesium sulfate and evaporated. Excess pyridine was again removed by azeotrope with toluene to afford 5.1 g of the title compound as a brown solid.

Provenance & Evidence