1 H NMR ( 400 MHz , CDCl 3 ) δ 9 . 41 ( s , 1 H ) , 8 . 91 - 8 . 78 ( br m , 1 H ) , 8 . 08 ( br s , 1 H ) , 8 . 06 ( d , J = 9 . 0 Hz , 1 H ) , 7 . 79 ( dd , J = 9 . 0 , 2 . 0 Hz , 1 H ) , 4 . 86 - 4 . 72 ( br m , 1 H ) , 4 . 30 - 4 . 12 ( br m , 1 H ) , 4 . 03 - 3 . 86 ( br m , 1 H ) , 3 . 86 - 3 . 71 ( m , 1 H ) , 3 . 64 - 3 . 52 ( br m , 1 H ) , 1 . 51 ( s , 9 H ) .