1 H NMR ( DMSO d 6 ) δ 8 . 42 ( 1 H , d , J = 4 . 6 Hz ) , 8 . 37 ( 1 H , br ) , 7 . 50 ( 1 H , s ) , 7 . 40 - 7 . 36 ( 2 H , m ) , 7 . 23 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 5 . 18 ( 0 . 7 H , d , J = 4 . 0 Hz ) , 5 . 13 ( 0 . 3 H , d , J = 4 . 0 Hz ) , 4 . 51 ( 1 H , br ) , 4 . 44 ( 0 . 7 H , s ) , 4 . 42 ( 0 . 7 H , s ) , 4 . 39 ( 0 . 3 H , s ) , 4 . 37 ( 0 . 3 H , s ) , 3 . 74 ( 0 . 3 H , br ) , 3 . 65 ( 0 . 7 H , br ) , 2 . 40 ( 2 . 1 H , s ) , 2 . 37 ( 0 . 9 H , s ) , 2 . 20 - 1 . 90 ( 2 H , m ) , 1 . 82 - 1 . 76 ( 2 H , m ) .