C([O:3][CH:4]([C:28](=[O:50])[CH:29]=[CH:30][CH:31]=[CH:32][CH:33]=[CH:34][CH:35]=[CH:36][CH:37]=[CH:38][CH:39]=[CH:40][CH2:41][CH2:42][CH2:43][CH2:44][CH2:45][CH2:46][CH2:47][CH2:48][CH3:49])[C:5](=[O:27])[CH:6]=[CH:7][CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=[CH:15][CH:16]=[CH:17][CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH2:25][CH3:26])=O.[OH-].[K+]>CCO>[C:28]([CH:4]([C:5](=[O:27])[CH:6]=[CH:7][CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=[CH:15][CH:16]=[CH:17][CH2:18][CH2:19][CH2:20][CH2:21][CH2:22][CH2:23][CH2:24][CH2:25][CH3:26])[OH:3])(=[O:50])[CH:29]=[CH:30][CH:31]=[CH:32][CH:33]=[CH:34][CH:35]=[CH:36][CH:37]=[CH:38][CH:39]=[CH:40][CH2:41][CH2:42][CH2:43][CH2:44][CH2:45][CH2:46][CH2:47][CH2:48][CH3:49]The above didocosahexaenoylmethyl formate (III, 1.38 g, 2.1 mmol) and KOH (300 mg) were stirred in 90% EtOH (70 mL) at room temperature under nitrogen for 90 min. Upon completion of the reaction, most of the solvent was evaporated. The resulting mixture was treated with 60 mL of 2M HCl solution. The aqueous phase was extracted with ether (2×75 mL). The combined ether extract was washed with water (2×50 mL), brine (50 mL), and dried over anhydrous MgSO4. Evaporation of the solvent gave 1.18 g of crude IV as yellowish oil. The crude product was purified by column chromatography on silica gel (230-400 mesh, 50 mL) eluted with 0-6% ethyl acetate gradient in hexanes. This gave 1.0 g of didocosahexaenoyl methanol (IV) as colourless oil.
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