1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 3 . 30 ( s , 3 H ) , 3 . 44 - 3 . 61 ( m , 4 H ) , 3 . 93 ( s , 3 H ) , 4 . 10 - 4 . 19 ( m , 1 H ) , 4 . 99 ( t , 1 H ) , 7 . 58 - 7 . 62 ( m , 2 H ) , 8 . 08 - 8 . 12 ( m , 3 H ) , 8 . 56 ( s , 1 H ) , 8 . 60 ( s , 1 H ) , 9 . 64 ( d , 1 H ) .