Br[C:2]1[C:17]([CH3:18])=[CH:16][CH:15]=[CH:14][C:3]=1[CH2:4][CH2:5][O:6][CH2:7][C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1.C([Li])(C)(C)C.CN(C)[CH:26]=[O:27].Cl>O1CCCC1.C(OCC)C.O>[CH2:7]([O:6][CH2:5][CH2:4][C:3]1[CH:14]=[CH:15][CH:16]=[C:17]([CH3:18])[C:2]=1[CH:26]=[O:27])[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1
To a solution of benzyl 2-bromo-3-methylphenethyl ether (3.2 g, 0.0105 mol) in dry tetrahydrofuran in a nitrogen atmosphere at −65° C. was added tert-butyllithium (1.7 M in pentane)(10.5 ml, 0.018 mol) and the mixture was stirred at −20° C. for 30 min. Dimethylformamide (1.5 g, 0.021 mol) was added dropwise at −65° C. and the mixture was stirred at −20° C. for 30 min and at room temperature for 1 h. To the solution was water added carefully and 2M HCl to make it acidic and the mixture was stirred for 30 min. To the mixture was added diethyl ether (50 ml), the organic layer was separated, washed with saturated sodium carbonate and water. The organic layer was separated, dried and evaporated under reduced pressure. Purification of the residue by column chromatography on silica gel using heptane:methylene chloride (2:8) as eluent gave 1.0 g (38.5%) of the title compound.
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