To a solution of tert-butyl (+/−)-4-(3-methylbutanoyl)benzoate (527 mg, 2.00 mmol) and 3-methylquinoline N-oxide (318 mg, 2.00 mmol) in dichloromethane (8.0 mL) was added diisopropylethylamine (1.31 mL, 7.50 mmol) followed by bromotripyrrolidinophosphonium hexafluorophosphate (1.18 g, 2.50 mmol). The solution was stirred at room temperature for 18 hours then diluted with sat. aq sodium bicarbonate (20 mL). The mixture was extracted with ethyl acetate (3×20 mL). The combined organics were dried over anhydrous Na2SO4 and filtered, and the filtrate was concentrated. Purification by silica gel flash chromatography (ethyl acetate/heptane) gave tert-butyl (+/−)-4-(3-methyl-1-((3-methylquinolin-2-yl)amino)butyl)benzoate as a white solid. 1H NMR (400 MHz, CDCl3) δ 7.94 (d, J=8.2 Hz, 2 H), 7.63 (d, J=8.2 Hz, 1 H), 7.59 (s, 1 H), 7.54-7.48 (m, 3 H), 7.47-7.41 (m, 1 H), 7.19-7.13 (m, 1 H), 5.56 (q, J=7.4 Hz, 1 H), 4.73 (d, J=7.0 Hz, 1 H), 2.28 (s, 3 H), 1.94-1.83 (m, 1 H), 1.81-1.70 (m, 1 H), 1.70-1.60 (m, 1 H), 1.57 (s, 9 H), 1.04 (d, J=6.6 Hz, 3 H), 0.97 (d, J=6.6 Hz, 3 H).
