[CH2:1]([O:8][C@H:9]([CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH3:25])[CH2:10][C:11]([O:13]C)=[O:12])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.O.[OH-].[Li+].Cl>C1COCC1.CO.CC#N.O>[CH2:1]([O:8][C@H:9]([CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH3:25])[CH2:10][C:11]([OH:13])=[O:12])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1Ester 31 (1.3 g, 3.73 mmol) was dissolved in THF/MeOH/CH3CN mixture (v/v/v, 1/1/1, 90 mL). Lithium hydroxide monohydrate (235 mg, 5.6 mmol) as a solution in water (30 mL) was added, and the mixture stirred overnight. The solvent amount was reduced in vacuo to about 30 mL. To the remaining aqueous solution was added 1 M hydrochloric acid to bring the pH down to 3. The aqueous layer was extracted with diethyl ether (3×40 mL). The combined organic extracts were dried over sodium sulfate. The drying agent was removed by filtration, and the solvents removed using a rotary evaporator. The residue was purified by chromatography on silica gel (40 g RediSep column, eluting with a gradient of 0% through 50% ethyl acetate/hexanes over 40 min, 40 mL/min) to give the product 33 (990 mg, 79%) as a colorless liquid. 1H NMR (300 MHz, CDCl3) δ 7.30-7.05 (m, 5H), 4.51 (s, 2H), 3.90-3.80 (m, 1H), 2.58-2.45 (m, 2H), 1.80-1.60 (m, 2H), 1.50-1.20 (m, 18H), 0.85 (t, J=5.8 Hz, 3H).
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