1 H - NMR ( 250 MHz , CDCl 3 ) δ 7 . 35 - 7 . 23 ( m , 5 H ) , 4 . 94 ( dd , 1 H , J 1 = 4 . 74 Hz , J 2 = 8 . 25 Hz ) , 3 . 64 ( br s , 3 H ) , 3 . 12 - 2 . 89 ( m , 2 H ) , 1 . 78 - 1 . 68 ( m , 2 H )