Reaction Steps
A solution of the crude ethyl-(2E, 4E, 6E)-7-(3,5-diisopropyl-2-n-heptyloxyphenyl)-3-methylocta-2,4,6-trienoate (500 mg, 1.10 mmol) in methanol (5 mL) was hydrolyzed with NaOH (1 mL of 5N aqueous solution) at reflux temperature. After 10 min, the mixture was cooled to room temperature and acidified with a 20% aqueous HCl solution. The solution was concentrated and the aqueous residue was extracted with EtOAc (2×10 mL). The EtOAc layer was washed with water (2×5 mL) and brine (5 mL), dried (MgSO4), filtered and concentrated. The major product (highest running spot by TLC) was isolated by preparative TLC (20% EtOAC-80% hexanes) to give (2E, 4E, 6E)-7-(3,5-diisopropyl-2-n-heptyloxyphenyl)-3-methylocta-2,4,6-trienoic acid (146) 220 mg (47%): TLC (10% MeOH-90% CHCl3) Rf=0.6; 1H NMR (CDCl3) δ 7.04(m, 1H, olefinic), 7.01(s, 1H, ArH ), 6.84(s, 1H, ArH ), 6.35(d, J=11.0 Hz, 1H, olefinic), 6.30(d, J=15.0 Hz, 1H, olefinic), 5.79(s, 1H, olefinic), 3.65(t, J=7.4 Hz, 2H, OCH2), 3.32(m, 1H, CH), 2.84(m, 1H, CH), 2.37(s, 3H, CH3), 2.19(s, 3H, CH3), 1.66(m, 2H, CH2), 1.31(m, 8H, 4CH2), 1.27(d, J=14.0 Hz, 6H, 2CH3), 1.24(d, J=14.0 Hz, 6H, 2CH3), 0.89(t, J=7.5 Hz, 3H, CH3).
