1 H - NMR ( DMSO - d 6 ) δ 8 . 95 ( t , 1 H - NH , J = 6 . 0 Hz ) , 8 . 52 ( s , 1 H ) , 7 . 89 ( d , 1 H , J = 8 . 4 Hz ) , 7 . 43 ( d , 1 H , J = 8 . 0 Hz ) , 5 . 82 ( d , 1 H , J = 7 . 6 Hz ) , 5 . 57 ( brs , 1 H ) , 5 . 38 ( brs , 1 H ) , 4 . 71 ( d , 1 H , J = 6 . 0 Hz ) , 4 . 60 ( brs , 1 H ) , 4 . 34 ( brs , 1 H ) , 3 . 41 ( dd , 1 H , J = 4 . 0 , 10 . 8 Hz ) , 2 . 80 ( dd , 1 H , J = 2 . 8 , 10 . 8 Hz ) ;