1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 1 . 17 ( d , 3 H ) , 3 . 40 - 3 . 50 ( m , 2 H ) , 3 . 99 - 4 . 10 ( m , 1 H ) , 4 . 96 ( t , 1 H ) , 7 . 58 - 7 . 62 ( m , 2 H ) , 8 . 03 - 8 . 07 ( m , 2 H ) , 8 . 68 ( s , 1 H ) , 9 . 25 ( s , 2 H ) , 9 . 29 - 9 . 32 ( m , 2 H ) .