[Synthesis]
To a stirred solution of compound 2 (1.0 eq.) in CH2Cl2 was slowly added a solution of BBr3 (1.9 eq.) in CH2Cl2 at -78 °C. After 1 hour of reaction, the mixture was slowly warmed to -25°C. Upon completion of the reaction, the reaction mixture was quenched with H2O and the solvent was subsequently evaporated to give the crude product. For compounds 3a to 3c, the pure product was obtained by recrystallization from MeOH/H2O solution as a yellow solid, while compound 3d was purified by silica gel column chromatography to give a yellow viscous oil. The 1H-NMR (CDCl3, 500 MHz) data for compound 3a (2-[4-(diethylamino)-2-hydroxybenzoyl]benzoic acid) were as follows: δ 12.65 (s, 1H), 8.07 (dd, 1H, J = 7.8, 0.9Hz), 7.58 (td, 1H, J = 7.6, 1.4Hz), 7.51 (td, 1H, J = 7.8, 1.4Hz), 7.51 (td, 1H, 1H, J = 7.6, 1.4Hz). J = 7.8, 1.4Hz), 7.34 (dd, 1H, J = 7.6, 1.1Hz), 6.91 (d, 1H, J = 8.9Hz), 6.11 (sd, 1H, J = 2.5Hz), 6.03 (dd, 1H, J = 9.2, 2.5Hz), 3.37 (q, 4H, J = 7.1Hz), 1.18 (t, 6H, J = 7.1 Hz).13C-NMR (CDCl3, 500 MHz) data were as follows: δ 199.0, 167.5, 165.2, 153.6, 140.6, 134.6, 131.6, 130.4, 129.5, 128.9, 127.6, 110.1, 103.5, 96.7, 124.5, 12.5. HRMS (EI) calculated value C19H21NO4 (M+): 313.1314, measured value: 313.1313. yield was 65%. |