1 H - NMR . δ ( CDCl 3 ) : 7 . 66 ( d , 1 H , J = 7 . 5 Hz ) , 7 . 62 ( d , 1 H , J = 8 . 0 Hz ) , 7 . 51 ( d , 4 H , J = 8 . 5 Hz ) , 7 . 38 - 7 . 44 ( m , 7 H ) , 7 . 26 - 7 . 35 ( m , 3 H ) , 7 . 20 - 7 . 25 ( m , 4 H ) , 7 . 13 ( dd , 1 H , J = 8 . 0 Hz , 1 . 5 Hz ) , 1 . 45 ( s , 6 H ) , 1 . 39 ( s , 36 H ) .