O[CH:2]([C:9]1[CH:14]=[CH:13][CH:12]=[C:11]([N+:15]([O-:17])=[O:16])[CH:10]=1)[CH2:3][C:4](=[O:8])[CH:5]([CH3:7])[CH3:6].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.C1(C)C=CC=CC=1>C(OCC)(=O)C>[CH3:6][CH:5]([CH3:7])[C:4](=[O:8])[CH:3]=[CH:2][C:9]1[CH:14]=[CH:13][CH:12]=[C:11]([N+:15]([O-:17])=[O:16])[CH:10]=1A mixture of 1-hydroxy-4-methyl-1-(3-nitrophenyl)pentan--3-one (3.32 g), p-toluenesulfonic acid monohydrate (0.03 g) and toluene (50 mL) was refluxed for 1 hour under Dean-Stark conditions. The mixture was diluted with ethyl acetate, washed (sat. sodium bicarbonate, water and brine) and the solvent removed. Chromatography (hexane/ethyl acetate, 3:1) yielded 4-methyl-1-(3-nitrophenyl)-1-penten-3-one (2.98 g) as a yellow solid. NMR: 1.11 (d,6, J=6.8, CH3), 3.02 (m,1, CH), 7.27 (d,1, J=16.2, CH), 7.73 (m,2, CH,Ar), 8.24 (m,2, Ar), 8.61 (m,1, Ar), MS: m/z=219(M).
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