1 H - NMR ( CDCl 3 ) : 7 . 824 ( d , 1 H , J = 8 . 8 Hz ) , 7 . 663 ( d , 1 H , J = 8 . 4 Hz ) , 7 . 272 ( s , 1 H ) , 7 . 243 ( d , 1 H , J = 8 Hz ) , 7 . 069 ( d , 1 H , J = 8 Hz ) , 6 . 868 ( dd , 1 H , J = 8 . 8 , 2 . 4 Hz ) , 6 . 751 ( d , 1 H , J = 2 . 4 Hz ) , 6 . 593 ( d , 1 H , J = 8 . 4 Hz ) , 6 . 536 ( d , 1 H , J = 9 . 6 Hz ) , 5 . 664 ( d , 1 H , J = 10 Hz ) , 5 . 026 ( s , 2 H ) , 4 . 562 ( s , 2 H ) , 3 . 798 ( s , 3 H ) , 3 . 15 ( br , 1 H ) , 2 . 418 ( s , 3 H ) , 1 . 427 ( s , 6 H )