1 H NMR ( CDCl 3 ) δ 8 . 88 ( 1 H , ddd , J = 4 . 3 , 1 . 8 , 1 . 2 Hz ) , 7 . 74 ( 1 H , br d , J = 7 . 9 Hz ) , 7 . 50 ( 1 H , dd , J = 7 . 9 , 4 . 3 Hz ) , 7 . 14 ( 3 H , br d , J = 7 . 9 Hz ) , 4 . 88 ( 1 H , d , J = 13 . 4 Hz ) , 4 . 82 ( 1 H , d , J = 13 . 4 Hz ) , 4 . 71 ( 1 H , dd , J = 14 . 1 , 5 . 5 Hz ) , 4 . 62 ( 1 H , dd , J = 14 . 1 , 5 . 5 Hz ) , 3 . 16 ( 1 H , m ) , 2 . 99 ( 1 H , m ) , 2 . 79 ( 1 H , m ) , 2 . 54 ( 1 H , m ) , 0 . 94 ( 9 H , s ) , 0 . 12 ( 3 H , s ) , 0 . 11 ( 3 H , s ) .