1 H NMR ( DMSO d 6 ) δ 8 . 48 ( 1 H , dd , J = 4 . 6 , 2 . 0 Hz ) , 8 . 12 ( 1 H , br t , J = 5 . 3 Hz ) , 7 . 53 ( 1 H , dd , J = 7 . 9 , 2 . 0 Hz ) , 7 . 47 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 32 ( 1 H , d , J = 2 . 0 Hz ) , 7 . 26 ( 1 H , dd , J = 7 . 9 , 4 . 6 Hz ) , 6 . 26 ( 1 H , s ) , 6 . 18 ( 1 H , s ) , 5 . 15 ( 1 H , br ) , 4 . 44 ( 2 H , d , J = 5 . 3 Hz ) , 2 . 74 ( 2 H , m ) , 2 . 40 ( 3 H , s ) , 2 . 15 ( 1 H , m ) , 1 . 86 ( 1 H , m ) .