[C:1]([O:12][CH2:13][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)(=[O:11])[C:2]1[C:3](=[CH:7][CH:8]=[CH:9][CH:10]=1)[C:4]([O-])=[O:5].C(Cl)(=O)C(Cl)=O.[BH4-].[Na+].OS([O-])(=O)=O.[K+]>CO>[OH:5][CH2:4][C:3]1[CH:7]=[CH:8][CH:9]=[CH:10][C:2]=1[C:1]([O:12][CH2:13][CH2:14][C:15]1[CH:16]=[CH:17][CH:18]=[CH:19][CH:20]=1)=[O:11]
25.2 g (93 mmol) monophenylethyl (−)-phthalate was heated at reflux in 50 ml oxalyl chloride (3 eq.) for 2 h. The excess oxalyl chloride was distilled under vacuum. The crude acid chloride was then diluted in 100 ml THF cooled to 0° under argon, and 7.4 g (2 eq.) NaBH4 was added. The reaction mixture was maintained under stirring at ambient temperature for 1 h, then cooled to 0° and 20 ml of methanol was added. After leaving the reaction mixture under stirring at ambient temperature for 1 h it was poured over cold 5% KHSO4 then extracted using diethyl ether. Chromatography of the crude product over silica gel (9:1 toluene/ether) yielded 12.1 g (47%) 2-phenylethyl 2-hydroxymethylbenzoate containing about 9% phthalide in the form of a white solid.
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