[CH2:1]([N:8]([CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)[C:9]1[CH:14]=[C:13]([CH3:15])[C:12](I)=[CH:11][C:10]=1[CH3:17])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C([Li])CCC.CN(C)[CH:32]=[O:33].Cl>C1(C)C=CC=CC=1.[Cl-].[Na+].O>[CH2:1]([N:8]([CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)[C:9]1[C:10]([CH3:17])=[CH:11][C:12]([CH:32]=[O:33])=[C:13]([CH3:15])[CH:14]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1To a stirred solution of dibenzyl-(4-iodo-2,5-dimethylphenyl)amine (9.35 g, 21.9 mmol) in toluene (100 mL) under nitrogen at −15° C. was added n-butyllithium in hexanes (1.6 M, 20.5 mL, 32.8 mmol) dropwise via syringe over a 30 min period. The resulting mixture was stirred at −15° C. for 15 min and then N,N-dimethylformamide (1.86 mL, 24.1 mmol) was added dropwise over a 10 min period. After 2 h, aqueous hydrochloric acid (1 M, 46.6 mL) and brine (30 mL) were added and the resulting mixture was stirred for 15 min. The layers were separated and the organic layer was extracted with brine, dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (0-50% DCM in hexanes) to give the title compound (3.60 g, 49% yield) as a clear oil.
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