Yield:91901-43-8 92%

Reaction Conditions:

with sulfuric acid for 24 h;Heating / reflux;

Steps:

32.1

A solution of 5-nitro-1-naphthoic acid (see Chem. Pharm. Bull., 32, 3968-80 (1984)) (5.995 g, 27.60 mmol) and conc. sulfuric acid (2 ml) in ethanol (100 ml) was heated under reflux for one day. The reaction solution was concentrated, diluted with ethyl acetate, and washed with aqueous sodium hydrogen carbonate solution and water. The obtained ethyl acetate solution was dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure to give the objective substance. yellow solid yield-6.212 g, 92% Recrystallization from ethanol gave a pale-yellow powder. mp 92-93°C; 1H-NMR (CDCl3, 200MHz) δ 1.48 (3H, t, J = 7.2 Hz), 4.50 (2H, q, J = 7.1 Hz), 7.67 (1H, dd, J = 7.6 Hz, 8.8 Hz), 7.74 (1H, dd, J = 7.2 Hz, 8.8 Hz), 8.20 (1H, dd, J = 1.1 Hz, 7.7 Hz), 8.29 (1H, dd, J = 1.1 Hz, 7.3 Hz), 8.66 (1H, td, J = 1.0 Hz, 8.8 Hz), 9.26 (1H, td, J = 1.0 Hz, 8.6 Hz); IR (KBr) 1725, 1520, 1354, 1277, 1155, 793, 764 cm-1; Anal. Calcd for C13H11NO4:! C, 63.67; H, 4.52; N, 5.71. Found: C, 63.45; H, 4.47; N, 5.69.

References:

EP1362846,2003,A1 Location in patent:Page/Page column 48-49