Step 2) Synthesis of 7-(benzyloxy)quinolin-4-ol: 5-((3-(benzyloxy)phenylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (300 g, 849.8 mmol) was dissolved in 1,2-dichlorobenzene (3 L) and heated to reflux for 5 hours. Upon completion of the reaction, the mixture was cooled to room temperature, followed by further cooling in an ice bath for 2 hours. The precipitated solid was collected by filtration and the solid was stirred with methanol (300 mL) for 2 hours at room temperature. The solid was collected by filtration again and dried under vacuum at 45 °C to afford the title compound 7-(benzyloxy)quinolin-4-ol as a light colored solid (103 g, 48.5% yield). Mass spectrum (ESI, positive ion mode) m/z: 252.2 [M + H]+; 1H NMR (400 MHz, DMSO-d6) δ: 5.23 (s, 2H), 5.98 (d, J = 7.2 Hz, 1H), 7.02 (t, 2H), 7.41 (t, 1H), 7.45 (t, J = 6.8 Hz, 2H), 7.52 (d J = 7.6Hz, 2H), 7.84 (t, J = 6.4Hz, 1H), 8.03 (d, J = 9.2Hz, 1H), 11.60 (s, 1H).
