1 H - NMR ( 400 MHz , CDCl 3 ) δ = 2 . 75 ( dd , 1 H , J 1 = 2 . 65 Hz , J 2 = 4 . 91 Hz ) , 2 . 91 ( dd , 1 H , J 1 = 4 . 2 Hz , J 2 = 4 . 8 Hz ) , 3 . 32 - 3 . 35 ( m , 1 H ) , 3 . 91 ( dd , 1 H , J 1 = 5 . 72 Hz , J 2 = 11 . 02 Hz ) , 4 . 20 ( dd , 1 H , J 1 = 3 . 06 Hz , J 2 = 11 . 00 Hz ) , 6 . 84 - 6 . 99 ( m , 4 H , Ph ) .