Reaction Steps
A 25 mL round-bottom flask was charged with 3 (340 mg, 2.15 mmol), NMP (10 mL), 4-iodobenzaldehyde, (499 mg, 2.15 mmol), and a magnetic stirring bar. The flask was fitted with a Hickman still, placed in an oil bath heated to 120° C., and stirred for 1 h. Then FeCl3.6H2O (29 mg, 0.11 mmol) was added to the reaction vessel and oxygen was bubbled through the mixture as it was heated and stirred for an additional 24 h. The reaction mixture was then removed from heat and added to ethyl acetate. The ethyl acetate solution was washed three times with water, then washed with brine, dried over Na2SO4, filtered, and concentrated to dryness. The residue (603 mg, 1.63 mmol) was suspended in CH3CN and heated to 80° C. Then DBU (243 μL, 1.63 μmol) was added and the mixture was stirred for 2 min, and iodopropane (159 μL, 1.63 mmol) was added. After 20 min, the mixture was treated with a second round of DBU and iodopropane, and after an additional 20 min, a third round of reagents was added. After a final 20 min of heating, the mixture was transferred to ethyl acetate and washed three times with water, followed by brine. After drying the organic layer over Na2SO4, the mixture was filtered, concentrated to dryness, and chromatographed (silica, CHCl3, 5% ethyl acetate), giving a white solid (440 mg, 50%): mp 208-209° C.; 1H NMR (CDCl3) δ 0.91 (t, J=7.6 Hz, 3H), 1.80-1.91 (m, 2H) 4.26 (t, J=7.6 Hz, 2H), 7.46 (d, J=8.0 Hz, 2H), 7.87 (s, 1H), 7.95 (d, J=8.0 Hz, 2H), 8.22 (s, 1H); 13C NMR (CDCl3) δ 11.4, 23.6, 47.4, 98.4, 109.0, 109.3, 116.55, 116.62, 116.9, 126.7, 128.2, 130.9, 137.8, 138.7, 145.3, 158.4; Anal. Calcd for C18H13IN4: C, 52.45; H, 3.18; N, 13.59. Found: C, 52.40; H, 3.06; N, 13.40.
