1 H - NMR ( CDCl 3 ) : 7 . 045 ( d , 1 H , J = 8 . 4 Hz ) , 6 . 996 ( s , 2 H ) , 6 . 728 ( d , 1 H , J = 2 Hz ) , 6 . 578 ( s , 1 H ) , 6 . 555 ( d , 1 H , J = 2 Hz ) , 6 . 521 ( dd , 1 H , J = 8 . 8 , 2 Hz ) , 5 . 989 ~ 5 . 920 ( m , 1 H ) , 5 . 649 ( d , 1 H , J = 10 Hz ) , 5 . 377 ~ 5 . 305 ( m , 2 H ) , 5 . 194 ( s , 2 H ) , 4 . 610 ( s , 2 H ) , 4 . 511 ( d , 2 H , J = 5 . 6 Hz ) , 2 . 571 ( s , 6 H ) , 2 . 334 ( s , 3 H ) , 1 . 425 ( s , 6 H )