[NH2:1][C:2]1[C:3]([CH3:8])=[CH:4][CH:5]=[CH:6][CH:7]=1.C(=O)([O-])[O-].[Na+].[Na+].Br[CH2:16][CH2:17][CH2:18][CH2:19]Br>CO.O>[C:3]1([CH3:8])[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=1[N:1]1[CH2:19][CH2:18][CH2:17][CH2:16]1To a solution of o-toluidine (2.0 g; 18.7 mmol) in methanol (62 mL) was added sodium carbonate (4.95 g; 46.75 mmol) followed by 1,4-dibromobutane (4.85 g; 22.4 mmol). The resulting mixture was stirred at 50° C. under a nitrogen atmosphere overnight and then diluted with water and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The crude residue was purified by automated silica gel column chromatography (Biotage®) eluting with ethyl acetate/hexanes (0 to 40% v/v over 900 mL gradient elution) to yield the title product as a dark yellow-orange oil (1.24 g).
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