1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 3 . 68 - 3 . 76 ( m , 1 H ) , 3 . 84 ( dt , 1 H ) , 3 . 93 ( s , 3 H ) , 4 . 81 - 4 . 94 ( m , 1 H ) , 5 . 47 ( t , 1 H ) , 7 . 58 - 7 . 63 ( m , 2 H ) , 8 . 10 - 8 . 15 ( m , 3 H ) , 8 . 60 ( s , 1 H ) , 8 . 65 ( s , 1 H ) , 10 . 12 ( d , 1 H ) .