1 H - NMR ( CDCl 3 ) : 7 . 979 ( d , 1 H , J = 8 . 8 Hz ) , 7 . 022 ~ 6 . 970 ( m , 2 H ) , 6 . 852 ( d , 1 H , J = 6 . 8 Hz ) , 6 . 569 ( d , 1 H , J = 8 . 4 Hz ) , 6 . 179 ( s , 1 H ) , 5 . 183 ( s , 2 H ) , 4 . 547 ( s , 2 H ) , 3 . 704 ( t , 2 H , J = 6 . 8 Hz ) , 3 . 1 ( br , 1 H ) , 2 . 783 ( t , 2 H , J = 6 . 4 Hz ) , 2 . 521 ( s , 6 H ) , 2 . 325 ( s , 3 H ) , 1 . 772 ~ 1 . 681 ( m , 4 H ) , 1 . 325 ( s , 6 H ) , 0 . 960 ( t , 3 H , J = 6 . 4 Hz )