1 H - NMR ( CDCl 3 ) : 7 . 942 ( d , 1 H , J = 8 . 8 Hz ) , 7 . 044 ( d , 1 H , J = 8 Hz ) , 6 . 978 ( s , 2 H ) , 6 . 876 ( dd , 1 H , J = 8 . 8 , 2 Hz ) , 6 . 586 ~ 6 . 545 ( m , 2 H ) , 6 . 293 ( d , 1 H , J = 2 . 4 Hz ) , 5 . 938 ~ 5 . 869 ( m , 1 H ) , 5 . 647 ( d , 1 H , J = 10 Hz ) , 5 . 327 ~ 5 . 263 ( m , 2 H ) , 5 . 156 ( s , 2 H ) , 4 . 563 ( d , 2 H , J = 2 . 4 Hz ) , 4 . 376 ( d , 2 H , J = 5 . 6 Hz ) , 3 . 092 ( br , 1 H ) , 2 . 529 ( s , 6 H ) , 2 . 334 ( s , 3 H ) , 1 . 421 ( s , 6 H )