1 H NMR ( 300 MHz , CDCl 3 ) δ 7 . 87 ( d , J = 1 . 8 Hz , 1 H ) , 7 . 58 ( d , J = 15 . 3 Hz , 1 H ) , 7 . 13 ( d , J = 1 . 8 Hz , 1 H ) , 6 . 80 ( d , J = 15 . 3 Hz , 1 H ) , 4 . 09 - 4 . 16 ( m , 2 H ) , 4 . 06 ( s , 3 H ) , 3 . 05 ( s , 3 H ) , 1 . 52 ( t , J = 6 . 9 Hz , 3 H ) .