The reaction was carried out by batchwise addition of 5-{[(4-iodophenyl)amino]methylene}-2,2-dimethyl-1,3-dioxane-4,6-dione (120 g) in diphenyl ether (1.3 L, 8.0 mol) at 240 °C for 1.5 hours. After completion of the reaction, the mixture was cooled to room temperature and poured into 1.5 L of hexane. The resulting suspension was filtered and the filter cake was broken and washed with hexane (2 x 500 mL). The solid was dried under vacuum to afford 6-iodo-4-hydroxyquinoline as a brown solid (80 g, 82% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ11.89 (d, J=4.0 Hz, 1H), 8.36 (d, J=2.3 Hz, 1H), 7.89-7.98 (m, 2H), 7.37 (d, J=8.6 Hz, 1H), 6.07 (dd, J=7.5,1.1 Hz, 1H); mass spectra (m /z) 272.0 (M+H+).
![5-[[(4-iodophenyl)amino]methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione](/CAS/20180702/GIF/909344-69-0.gif)
