5-amino-3,4-dihydro-4-hydroxy-4-(trifluoromethyl)-1H-quinolin-2-one → 5-hydroxy-4-(trifluoromethyl)-1H-quinolin-2-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-amino-3,4-dihydro-4-hydroxy-4-(trifluoromethyl)-1H-quinolin-2-one (6.0 g, 24 mmol) in 100 mL 4.8 M H2SO4 was added a solution of NaNO2 (1.85 g, 26.8 mmol) in 6 mL water at 0° C. The reaction mixture became deep red. This solution was transferred to 120 mL 10M H2SO4 preheated to 145° C. The mixture was heated at 145° C. for 0.5 h, then poured into 400 g of ice water. The crude solid was adsorbed onto silica gel and eluted with 9:1 CH2Cl2:MeOH to afford 4.6 g (82%) of 5-hydroxy-4-(trifluoromethyl)-1H-quinolin-2-one, an off-white solid. 1H NMR (400 MHz, acetone-d6) δ 11.0 (broad s, 1H), 9.64 (s, 1H), 7.42 (t, 1H, J=8.1), 6.99 (d, 1H, J=8.1), 6.90 (s, 1H), 6.79 (d, 1H, J=8.1).

Provenance & Evidence