Reaction Steps
To a solution of 8-phenyl-1,6-naphthyridin-5-one (142 mg, 0.6 moles) in 5 ml DMF was added solid potassium carbonate. The resulting suspension was stirred under nitrogen at 21° C. for 30 minutes. Iodoethane (0.13 ml, 1.6 moles) was added and the reaction mixture heated overnight to 80° C. The mixture was cooled and concentrated under vacuum, and chromatographed by silica gel [column chromatography, eluting with 1:1 ethyl acetate/hexanes] to give 70 mg (47% yield) of the desired 6-ethyl-8-phenyl-1,6-naphthyridin-5-one as a white solid. Characteristic analytical data are as follows: mp 141.5°-141.7° C.; 1H NMR (CDCl3, 300 MHz) δ1.44 (t, 3H, J=7.2 Hz), 4.12 (q, 2H, J=7.2 Hz) , 7.38-7.63 (m, 7H), 8.78 (dd, 1H, J=8.1, 2.0 Hz), 8.95 (dd, 1 H, J=4.6, 1.8 Hz); 13C NMR (75 MHz, CDCl3) δ161.59, 154.09, 151.99, 136.51, 135.38, 134.01, 129.98, 128.38, 127.66, 121.96, 121.74, 120.98, 44.52, 14.67; IR (KBr) vmax 1647, 1620, 1597, 1587, 1550, 1498, 1437, 1375, 1298, 1246, 1178, 1169, 792, 758, 726, 694, 626, 598, 499, 455 cm-1 ; mass spectrum (EI), m/e 250. Anal. (C16H14N2O) Calcd.: C, 76.78; H, 5.64; N, 11.19. Found C, 76.78; H, 5.61; N, 11.18.
