Nitrogen → 2,2-dimethyl-6-cyano-3,4-dihydro-2H-1,3-benzoxazin-4-one

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Reaction Steps

1.9 g of 1H-2-pyridone are added to a stirred slurry of 741 mg of NaH (80%) in 40 ml of dry DMF while passing N2 into the flask. After the mixture has been stirred for 0.5 hour, 2.2 g of 2,2-dimethyl-4-chloro-6-cyano-2H-1,3-benzoxazine ("IIa"; m.p. 127°-129°; obtainable by condensing 5-cyano-2-hydroxybenzamide with acetone to form 2,2-dimethyl-6-cyano-3,4-dihydro-2H-1,3-benzoxazin-4-one (m.p. 213°-216°) and subsequently reacting the product with POCl3 /PCl5) are added, and the mixture is stirred at 50° for a further 72 hours. Saturated NaCl solution is subsequently added, the mixture is extracted with ethyl acetate, the organic phase is washed with NaCl solution, dried over sodium sulfate and evaporated, and the residue is chromatographed on silica gel (ethyl acetate/petroleum ether). 2,2-Dimethyl-4-(2-pyridyl-oxy)-6-cyano-2H-1,3-benzoxazine ("A"; m.p. 115°- 116°) is obtained as the first fraction, and 2,2-dimethyl-4-(2-oxo-1,2-dihydropyridyl)-6-cyano-2H-1,3-benzoxazine ("B"; m.p. 158°-159°) as the second fraction.

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