1 H NMR ( 400 MHz , CDCl 3 ) δ 9 . 11 ( s , 1 H ) , 8 . 60 ( br s , 1 H ) , 8 . 15 ( d , J = 9 . 0 Hz , 1 H ) , 7 . 92 ( dd , J = 8 . 8 , 1 . 8 Hz , 1 H ) , 6 . 84 ( d , J = 8 . 0 Hz , 1 H ) , 6 . 22 ( dd , J = 8 . 3 , 2 . 3 Hz , 1 H ) , 6 . 16 ( d , J = 2 . 0 Hz , 1 H ) , 4 . 33 - 4 . 44 ( m , 2 H ) , 4 . 02 - 4 . 10 ( m , 1 H ) , 3 . 77 - 3 . 87 ( m , 1 H ) , 3 . 68 ( s , 3 H ) , 3 . 50 ( s , 3 H ) , 3 . 36 - 3 . 46 ( m , 2 H ) , 1 . 95 - 2 . 10 ( m , 3 H ) , 1 . 67 - 1 . 78 ( m , 1 H ) , 1 . 23 ( d , J = 6 . 0 Hz , 3 H ) .