1 H NMR ( DMSO d 6 ) δ 8 . 42 ( 1 H , d , J = 4 . 6 Hz ) , 8 . 37 ( 1 H , br ) , 7 . 49 ( 1 H , br s ) , 7 . 37 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 36 ( 1 H , br s ) , 7 . 23 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 5 . 18 ( 1 H , d , J = 4 . 0 Hz ) , 4 . 52 ( 1 H , d , J = 4 . 0 Hz ) , 4 . 43 ( 2 H , d , J = 4 . 0 Hz ) , 3 . 66 ( 1 H , dd , J = 8 . 6 , 5 . 9 Hz ) , 2 . 40 ( 3 H , s ) , 2 . 18 - 1 . 99 ( 2 H , m ) , 1 . 84 - 1 . 79 ( 2 H , m ) .