1 H NMR ( 400 MHz , CD 3 Cl ) δ 7 . 05 ( br d , J = 6 . 6 Hz , 2 H ) , 6 . 73 ( br d , J = 6 . 8 Hz , 1 H ) , 5 . 65 ( br d , J = 3 . 1 Hz , 1 H ) , 3 . 79 ( ddd , J = 1 . 5 , 5 . 0 , 14 . 7 Hz , 1 H ) , 3 . 41 ( br d , J = 14 . 8 Hz , 1 H )