[OH:1]/[N:2]=[C:3](\Cl)/[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.CO[CH:13]=[CH:14][C:15](=[O:17])[CH3:16].C(N(CC)CC)C>ClCCl>[C:4]1([C:3]2[C:14]([C:15](=[O:17])[CH3:16])=[CH:13][O:1][N:2]=2)[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1To a mixture of (E)- and/or (Z)-N-hydroxy-benzenecarboximidoyl chloride (7.41 g, 48 mmol) and 4-methoxy-3-buten-2-one (4.77 mL, 48 mmol) in dichloromethane (48 mL) was added triethylamine (6.64 mL, 48 mmol) dropwise under ice-bath cooling keeping the temperature below 5° C. The reaction mixture was then stirred at 5° C. for 15 min, and then the ice-bath was removed and stirring was continued for 30 min (resulting in an increase in temperature to 32° C. Then the mixture was re-cooled under ice-bath cooling for another 30 min and then the ice-bath was removed again and allowed to warm up to room temperature and left overnight. The resulting mixture was then poured into HCl (1 N) and ice-water and then extracted with ethyl acetate. The organic extract was then dried over sodium sulphate and evaporated to leave a yellow oil. Purification by chromatography (SiO2, heptane:ethyl acetate=100:0 to 50:50) afforded the title compound (6.35 g, 71%) which was obtained as a light yellow solid. MS: m/e (EI)=187.1 [M].
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