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A solution of 10.0 g (62 mmol) of 3,4-dihydro-1-benzoxepin-5(2H)-one (J. Chem. Soc., Perkin Trans. 1 (1991), 2763) and 4.63 g (68 mmol) of hydroxylamine hydrochloride in 45 ml of ethanol and 45 ml of pyridine was heated under reflux for 5 h. After distilling off the solvents on a rotary evaporator, the residue was treated with water, adjusted to pH 2 with dil. hydrochloric acid and stirred for 3 h. After filtering off the precipitated product with suction and drying it, 10.2 g of 3,4-dihydro-1-benzoxepin-5(2H)-one oxime were obtained, m.p. 96-98° C.

1. temperatureunder reflux for 5 h
2. distillationAfter distilling off the solvents
3. customon a rotary evaporator
4. additionthe residue was treated with water
5. filtrationAfter filtering off the precipitated product with suction
6. customdrying it