[H-].[Na+].[Br-].[C:4]([CH2:7][CH2:8][CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)([OH:6])=[O:5].[CH3:34][C:35]1[CH:42]=[CH:41][CH:40]=[C:39]([CH3:43])[C:36]=1[CH:37]=O.Cl>O1CCCC1.O>[CH3:34][C:35]1[CH:42]=[CH:41][CH:40]=[C:39]([CH3:43])[C:36]=1[CH:37]=[CH:14][CH2:13][CH2:12][CH2:11][CH2:10][CH2:9][CH2:8][CH2:7][C:4]([OH:6])=[O:5]Sodium hydride (60% dispersion in mineral oil; 0.65 g, 16 mmol) was added portionwise at room temperature to a stirred solution of (8-carboxy-octyl)-triphenyl-phosphonium bromide (2.8 g, 5.6 mmol) in tetrahydrofuran (30 mL) at room temperature, then after 1 hour 2,6-dimethylbenzaldehyde (757 mg, 5.64 mmol) was added portionwise to the reaction mixture and the solution stirred for 2 days at room temperature. On reaction completion, water (10 ml) was added and the solution acidified to pH 3 with concentrated hydrochloric acid. The product was extracted with ethyl acetate, the organic layer dried over magnesium sulfate, filtered and evaporated. Chromatography (SiO2, heptane-ethyl acetate 4:1) afforded 10-(2,6-dimethyl-phenyl)-dec-9-enoic acid as a colorless oil.
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