1 H NMR ( 400 MHz , chloroform - d 1 ) δ = 7 . 55 ( d , J = 9 . 2 Hz , 2 H ) , 7 . 52 ( d , J = 4 . 4 Hz , 1 H ) , 7 . 49 ( d , J = 9 . 2 Hz , 2 H ) , 7 . 00 ( d , J = 4 . 4 Hz , 1 H ) , 4 . 89 - 4 . 81 ( m , 1 H ) , 4 . 09 - 3 . 99 ( m 2 H ) , 3 . 94 - 3 . 88 ( m , 2 H ) , 3 . 85 - 3 . 73 ( m 2 H ) , 3 . 68 - 3 . 56 ( m , 2 H ) , 2 . 79 ( s , 3 H )