1 H - NMR ( CDCl 3 , 300 MHz ) : δ 8 . 11 ( s , 2 H ) , 7 . 99 - 7 . 86 ( m , 4 H ) , 7 . 44 - 7 . 05 ( m , 8 H ) , 6 . 36 - 6 . 29 ( m , 2 H ) , 5 . 99 ( t , 1 H ) , 5 . 64 ( t , 1 H ) , 5 . 36 ( t , 1 H ) , 4 . 58 ( m , 2 H ) , 3 . 06 ( m , 2 H ) 1 . 44 ( s , 18 H ) , 1 . 33 ( s , 2 H ) , 0 . 03 ( s , 9 H ) .