C([O:5][C:6](=[O:23])[CH2:7][C:8]1([OH:22])[CH2:13][CH:12]2[CH2:14][CH2:15][CH:9]1[CH:10]=[C:11]2[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1)(C)(C)C.O[Li].O.O.CO>CCO>[OH:22][C:8]1([CH2:7][C:6]([OH:23])=[O:5])[CH2:13][CH:12]2[CH2:14][CH2:15][CH:9]1[CH:10]=[C:11]2[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1To a solution of 4.0 g of rac-(1R*,2R*,4R*)-(2-hydroxy-5-phenyl-bicyclo[2.2.2]oct-5-en-2-yl)-acetic acid tert.-butyl ester in 25 mL EtOH were added 2.1 g of LiOH.H2O, 8 mL H2O and 22 mL MeOH. The reaction mixture was stirred at rt for 3 d and then concentrated. The residue was partitioned between water and Et2O. The aq. layer was separated and acidified with 1N HCl resulting in the formation of a white solid. The solid was filtrated, washed with 5 mL aq. HCl and dried in vacuo to obtain 3.2 g of rac-(1R*,2R*,4R*)-(2-hydroxy-5-phenyl-bicyclo[2.2.2]oct-5-en-2-yl)-acetic acid as white solid.
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