1 H NMR ( 300 MHz , CDCl 3 ) δ 6 . 55 ( t , 1 H , J = 1 . 2 Hz ) , 5 . 83 ( m , 1 H ) , 5 . 05 ( m , 1 H ) , 4 . 99 ( m , 2 H ) , 3 . 96 ( m , 4 H ) , 3 . 43 ( dd , 1 H , J = 9 . 6 , 17 . 7 Hz ) , 3 . 25 ( t , 1 H , J = 9 . 6 Hz ) , 2 . 36 ( m , 1 H ) , 2 . 25 ( m , 1 H ) , 2 . 11 ( ddd , 1 H , J = 8 . 4 , 11 . 4 , 19 . 8 Hz ) , 1 . 89 ( m , 1 H )