Yield : 71 . 2 mg ( 81 %); R f = 0 . 3 ( MeOH : dichloromethane = 1 : 20 ) ; Yellow solid ; Melting point : 225 - 227 ℃; 1 H NMR ( 400 MHz , CDCl 3 ) δ 9 . 08 ( d , J = 5 . 6 Hz , 2 H ) , 8 . 18 ( t , J = 7 . 8 Hz , 1 H ) , 7 . 89 ( t , J = 7 . 1 Hz , 2 H ) , 7 . 73 - 7 . 68 ( m , 3 H ) , 7 . 31 - 7 . 27 ( m , 2 H ) 7 . 25 - 7 . 20 ( m , 3 H ) , 7 . 20 - 7 . 15 ( m , 5 H ) , 3 . 38 ( s , 3 H ) .