1 H - NMR ( CDCl 3 ) : 7 . 948 ( d , 1 H , J = 8 Hz ) , 7 . 065 ( d , 1 H , J = 8 Hz ) , 6 . 992 ( d , 1 H , J = 8 Hz ) , 6 . 758 ( s , 1 H ) , 6 . 618 ( d , 1 H , J = 10 Hz ) , 6 . 580 ( d , 1 H , J = 8 Hz ) , 5 . 660 ( d , 1 H , J = 10 Hz ) , 5 . 194 ( s , 2 H ) , 4 . 630 ( d , 2 H , J = 6 Hz ) , 3 . 875 ( s , 3 H ) , 3 . 431 ( t , 1 H , J = 6 . 4 Hz ) , 2 . 624 ( t , 2 H , J = 7 . 6 Hz ) , 1 . 692 ~ 1 . 617 ( m , 2 H ) , 1 . 431 ( s , 6 H ) , 0 . 955 ( t , 3 H , J = 7 . 2 Hz )