1 H NMR ( 400 MHz , DMSO - d 6 ) δ [ ppm ] = 3 . 37 - 3 . 46 ( m , 2 H ) , 3 . 69 ( s , 3 H ) , 3 . 83 ( s , 3 H ) , 3 . 99 - 4 . 06 ( m , 1 H ) , 6 . 30 ( d , 1 H ) , 7 . 49 - 7 . 56 ( m , 2 H ) , 7 . 71 ( d , 1 H ) , 7 . 78 - 7 . 83 ( m , 2 H ) .