1 H NMR ( DMSO d 6 ) δ 9 . 27 ( 1 H , br s ) , 8 . 74 ( 1 H , d , J = 4 . 5 Hz ) , 7 . 75 - 7 . 80 ( 2 H , m ) , 7 . 62 ( 1 H , d , J = 2 . 1 Hz ) , 7 . 53 ( 1 H , dd , J = 8 . 0 , 4 . 7 Hz ) , 7 . 45 ( 1 H , dd , J = 8 . 4 , 2 . 1 Hz ) , 7 . 36 ( 1 H , d , J = 8 . 3 Hz ) , 4 . 40 ( 2 H , t , J = 5 . 3 Hz ) , 3 . 88 ( 1 H , d , J = 8 . 6 Hz ) , 3 . 53 ( 1 H , d , J = 8 . 4 Hz ) , 2 . 29 - 2 . 48 ( 5 H , m ) .