[O:1]=[C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH2:5][C@@H:4]([C:12]([O:14][CH3:15])=[O:13])[CH2:3]1.[CH2:16](O)[CH2:17][OH:18].C1(C)C=CC(S(O)(=O)=O)=CC=1>C1C=CC=CC=1>[C:2]12([O:18][CH2:17][CH2:16][O:1]1)[C:11]1[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=1)[CH2:5][C@@H:4]([C:12]([O:14][CH3:15])=[O:13])[CH2:3]2To the stirred solution of (R)-methyl 4-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylate (4.5 g, 22.03 mmol) in benzene (40 mL), ethane-1,2-diol (3.69 mL, 66.1 mmol) and a catalytic amount of p-toluenesulfonic acid was added. The reaction mixture was heated to reflux temperature and further maintained for 20 hours. After 20 hours, the reaction mixture was allowed to RT, concentrated under vacuum to yield 12 g of crude compound. Crude material was purified by flash chromatography (Biotage) using 7% ethyl acetate:hexane get title compound (4.7 g) m/z 248.6.
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