1 H NMR ( 300 MHz , CDCl 3 ) δ : 7 . 48 ( d , J = 7 . 9 Hz , 1 H ) , 7 . 30 - 7 . 25 ( m , 2 H ) , 7 . 10 - 7 . 05 ( m , 1 H ) , 4 . 64 ( br s , 1 H ) , 3 . 24 - 3 . 22 ( m , 1 H ) , 1 . 49 ( s , 9 H ) , 0 . 98 ( d , J = 6 . 4 Hz , 6 H ) .