1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 3 . 35 - 3 . 41 ( m , 1 H ) , 3 . 62 - 3 . 69 ( m , 1 H ) , 3 . 78 - 3 . 91 ( m , 1 H ) , 5 . 94 ( dt , 1 H ) , 6 . 00 ( br d , 1 H ) , 7 . 57 - 7 . 61 ( m , 2 H ) , 7 . 64 ( ddd , 1 H ) , 7 . 99 - 8 . 04 ( m , 2 H ) , 8 . 17 ( ddd , 1 H ) , 8 . 68 ( s , 1 H ) , 8 . 69 ( dd , 1 H ) , 8 . 92 ( d , 1 H ) , 9 . 54 ( t , 1 H ) .