1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 1 . 18 ( d , 3 H ) , 3 . 42 - 3 . 52 ( m , 2 H ) , 3 . 99 - 4 . 10 ( m , 1 H ) , 4 . 97 ( t , 1 H ) , 7 . 58 - 7 . 63 ( m , 2 H ) , 8 . 07 - 8 . 12 ( m , 2 H ) , 8 . 64 ( s , 1 H ) , 9 . 13 ( s , 1 H ) , 9 . 39 ( d , 1 H ) , 9 . 61 ( s , 1 H ) .