1 H NMR ( 300 MHz , CDCl 3 ) : 6 . 28 ( t , J = 2 . 6 Hz , 2 H ) , 6 . 19 ( t , J = 2 . 6 Hz , 2 H ) , 3 . 31 ( t , 6 . 6 Hz , 2 H ) , 2 . 62 ( t , J = 8 Hz ) , 1 . 7 - 1 . 3 ( m , 8 H ) , 1 . 17 ( s , 9 H ) .