Reaction Steps
Following a reported procedure, a sample of 3 (265 mg, 0.70 mmol) in NMP (2.5 mL) was heated to 120° C. and treated with DBU (105 μL, 0.70 mmol). After stirring for 2 min, iodopropane (105 μL, 0.70 mmol) was added and the mixture was stirred for 15 min. A second dose of DBU (68 μL, 0.70 mmol), followed by iodopropane (68 μL, 0.70 mmol), was added, and 15 min later, a third identical round of DBU and iodopropane was again added. After the mixture was stirred for 15 min, the reaction mixture was allowed to cool and was diluted with ethyl acetate. The organic solution was washed with water and brine. The organic layer was dried (Na2SO4), filtered, concentrated, and chromatographed (silica, CH2Cl2 w/ethyl acetate gradient of 0-5%). Some starting material was recovered (83 mg, 31%), and fractions containing the product were concentrated to give a colorless solid (183 mg, 62%): mp 132-134° C.; 1H NMR δ 0.92 (t, J=8.0 Hz, 3H), 1.82-1.93 (m, 2H), 2.52 (d, J=8.8 Hz, 6H), 4.31 (t, J=7.6 Hz, 2H), 4.98-5.09 (m, 6H), 5.50-5.63 (3H), 7.53 (d, J=8.4 Hz, 2H), 7.70 (d, J=8.4 Hz, 2H), 7.88 (s, 1H), 8.19 (s, 1H); 13C NMR δ 11.4, 23.5, 41.9, 44.1, 47.3, 108.5, 109.0, 116.7, 116.8, 118.5, 126.1, 126.4, 127.9, 129.2, 134.0, 137.9, 145.4, 149.9, 159.4; Anal. Calcd for C28H28N4: C, 79.97; H, 6.71; N, 13.32. Found: C, 79.93; H, 6.73; N, 13.35.
