To a solution of 4-(2-(5-amino-8-methylbenzo[f][1,7]naphthyridin-2-yl)ethyl)phenol (from Example 170) (1.0 equiv.) and triethyl amine (2 equiv.) in dichloromethane (0.10 M) at 0° C. was added ethyl chloroformate (1.2 equiv.). The resulting mixture was allowed to stir for 30 minutes at 0° C., after which it was diluted with water and dichloromethane. The biphasic layers were separated and the aqueous layer was washed twice with dichloromethane. The combined organic layers were dried over anhydrous Na2SO4 and the volatiles were removed in vacuo. The resulting residue was purified by a COMBIFLASH® system (ISCO) using 0-50% ethyl acetate in hexanes to provide 4-(2-(5-amino-8-methylbenzo[f][1,7]naphthyridin-2-yl)ethyl)phenyl ethyl carbonate as a solid. 1H NMR (Acetone-d6): δ 8.78 (s, 1H), 8.73 (s, 1H), 8.28 (d, 1H), 7.43 (s, 1H), 7.33 (d, 2H), 7.10-7.17 (m, 3H), 6.64 (br, 2H), 4.18 (t, 2H), 3.25 (t, 2H), 3.14 (t, 2H), 2.45 (s, 3H), 1.68-1.77 (m, 2H), 0.97 (t, 3H). LRMS [M+H]=416.2
