1 H - NMR . δ ( CDCl 3 ) : 7 . 57 ( d , 1 H , J = 7 . 5 Hz ) , 7 . 40 - 7 . 47 ( m , 2 H ) , 7 . 32 - 7 . 39 ( m , 4 H ) , 7 . 27 - 7 . 31 ( m , 2 H ) , 7 . 27 - 7 . 24 ( m , 5 H ) , 6 . 94 - 7 . 09 ( m , 6 H ) , 6 . 83 ( brs , 2 H ) , 1 . 33 ( s , 18 H ) , 1 . 32 ( s , 6 H ) , 1 . 20 ( s , 9 H ) .