1 H NMR ( 400 MHz , CDCl 3 ) : δ 7 . 10 ( m , 1 H ) , 6 . 91 ( m , 1 H ) , 5 . 57 ( m , 1 H ) , 5 . 45 ( m , 2 H ) , 4 . 18 ( m , 2 H ) , 3 . 97 ( s , 3 H ) , 3 . 36 ( t , 1 H ) , 2 . 98 ( m , 2 H ) , 2 . 26 ( m , 2 H ) , 1 . 60 ( d , 3 H ) , 1 . 40 ( s , 9 H ) .