1 H - NMR . δ ( CDCl 3 ) : 7 . 66 ( d , 1 H , J = 7 . 5 Hz ) , 7 . 63 ( d , 1 H , J = 8 . 0 Hz ) , 7 . 59 ( d , 2 H , J = 7 . 5 Hz ) , 7 . 52 ( dt , 2 H , J = 2 . 0 Hz , 8 . 5 Hz ) , 7 . 39 - 7 . 45 ( m , 7 H ) , 7 . 36 ( d , 4 H , J = 2 . 5 Hz ) , 7 . 29 - 7 . 34 ( m , 6 H ) , 7 . 26 - 7 . 29 ( m , 1 H ) , 7 . 19 ( dd , 1 H , J = 2 . 5 Hz , 8 . 0 Hz ) , 1 . 47 ( s , 6 H ) , 1 . 33 ( s , 36 H ) .