1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 1 . 19 ( d , 3 H ) , 3 . 42 - 3 . 52 ( m , 2 H ) , 4 . 00 - 4 . 11 ( m , 1 H ) , 4 . 96 ( br s , 1 H ) , 7 . 57 - 7 . 62 ( m , 2 H ) , 8 . 07 - 8 . 13 ( m , 2 H ) , 8 . 14 - 8 . 55 ( m , 2 H ) , 8 . 59 ( s , 1 H ) , 9 . 52 ( d , 1 H ) , 13 . 24 ( br s , 1 H ) .