1 H - NMR ( CDCl 3 ) : 7 . 814 ( d , 1 H , J = 8 . 8 Hz ) , 7 . 662 ( dd , 2 H , J = 6 . 8 , 1 . 6 Hz ) , 7 . 241 ( d , 2 H , J = 8 Hz ) , 7 . 070 ( d , 1 H , J = 8 . 4 Hz ) , 6 . 864 ( dd , 1 H , J = 8 . 8 , 1 . 6 Hz ) , 6 . 769 ( d , 1 H , J = 2 . 4 Hz ) , 6 . 598 ( dd , 1 H , J = 8 , 0 . 4 Hz ) , 6 . 533 ( dd , 1 H , J = 10 , 0 . 4 Hz ) , 5 . 668 ( d , 1 H , J = 10 Hz ) , 5 . 017 ( s , 2 H ) , 4 . 563 ( d , 2 H , J = 4 . 4 Hz ) , 3 . 905 ( t , 2 H , J = 6 . 8 Hz ) , 3 . 079 ( br , 1 H ) , 2 . 423 ( s , 3 H ) , 1 . 829 ~ 1 . 777 ( m , 2 H ) , 1 . 431 ( s , 6 H ) , 1 . 027 ( t , 3 H , J = 3 . 6 Hz )