4-Methyl-1,7-diphenyl-1,6-heptadiene-3,5-dione → 4-Methyl-1,7-diphenylheptane-3,5-dione

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4-Methyl-1,7-diphenyl-1,6-hetpadiene-3,5-dione (6b, 0.96 g, 3.3 mmol) and palladium on activated carbon (0.25 g, 10%) were combined in ethyl acetate (50 ml). The mixture was placed under a hydrogen atmosphere (60 psi) on a Parr apparatus for 2 hr at room temperature. The resulting mixture was filtered through celite and the filtrate was washed with saturated sodium chloride, dried over magnesium sulfate, filtered and evaporated to afford an oil. The crude oil was twice chromatographed on silica gel with ethyl acetate/hexane to give an oil. The oil was distilled bulb to bulb to give 0.71 g (73%) of a clear oil; 1H NMR: δ enol form: 1.66 (s, 3H), 2.73 (m, 8H), 7.17 (m, 10H); keto form: 1.20 (d, 3H, J=7.2 Hz), 2.73 (m, 8H), 3.55 (q, 1H, J=7.0 Hz), 7.17 (m, 10H); 13C NMR: δ 12.3, 29.3, 31.0, 37.6, 42.8, 60.9, 104.2, 125.9, 128.1, 128.2, 140.4, 140.8, 174.6, 191.5, 205.6; Exact mass calcd for C20H22O2: 294.1620, observed (M+H) 295.1693.

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