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0 °C

1.1 equivalents of n-butyllithium are added to 309 mg (0.89 mmol) of chloromethyltriphenylphosphonium chloride in 5 ml of tetrahydrofuran cooled to 0° C. After stirring for one hour, 150 mg (0.74 mmol) of 7-acetyl-1-benzoxepin-3(2H)-one, prepared according to example 79, are added at ambient temperature. The medium is stirred for a further 1 hour. After the usual treatments and evaporating the solvent under reduced pressure, the crude reaction product is taken up in pentane in order to precipitate triphenylphosphine oxide. Evaporation of the solvents provides 95.5 mg (55%) of 1-[3-(chloromethylene)-2,3-dihydro-1-benzoxepin-7-yl]ethanone in the form of a mixture of two Z/E isomers in a 90/10 ratio; 1H NMR (C6D6): 7.85 (d, 1H, J=2.2 Hz), 7.76 (dd, 2.2 Hz and 8.4 Hz), 7.04 (d, 8.4 Hz), 6.85 (d, J-=11.8 Hz, 1H), 6.57 (d, J=11.8 Hz, 1H), 6.16 (s, 1H), 4.57 (4.87) (s, 2H), 2.56 (s, 3H).

1. additionare added at ambient temperature
2. stirringThe medium is stirred for a further 1 hour
3. customAfter the usual treatments and evaporating the solvent under reduced pressure
4. customthe crude reaction product
5. customto precipitate triphenylphosphine oxide
6. customEvaporation of the solvents