[CH:1]1([C:5]2[C:13](I)=[CH:12][C:8]([C:9]([OH:11])=[O:10])=[C:7]([CH3:15])[CH:6]=2)[CH2:4][CH2:3][CH2:2]1.[O:16]1CCC[CH2:17]1.C([Li])CCC.CN(C)C=O>CCOCC>[CH:1]1([C:5]2[C:13]([CH:17]=[O:16])=[CH:12][C:8]([C:9]([OH:11])=[O:10])=[C:7]([CH3:15])[CH:6]=2)[CH2:4][CH2:3][CH2:2]1Into a three neck round-bottom flask, which was purged and maintained with an inert atmosphere of nitrogen, was placed a solution of 4-cyclobutyl-5-iodo-2-methylbenzoic acid (compound 62.1, 5.00 g, 80%, 12.7 mmol) in a solvent mixture of tetrahydrofuran and Et2O (50 mL/50 mL). The solution was cooled to −78° C. then n-butyllithium (15 mL, 2.5 M in hexanes) was added drop-wise with stirring. N,N-Dimethylformamide (2.64 mL, 34.2 mmol) was added and the resulting mixture was stirred for 1 h at −78° C., then carefully quenched by slow addition of aqueous NH4Cl (sat., 50 mL). The pH was adjusted to 1-2 with aqueous hydrogen chloride (6 M), then diluted with ethyl acetate (100 mL) and washed with brine (4×50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified using silica gel column chromatography with ethyl acetate/petroleum ether (1:1) as the eluent to furnish 1.62 g (41%) of the title compound as a white solid.
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