1 H NMR ( 400 MHz , DMSO - d 6 ) δ [ ppm ] = 1 . 16 ( d , 3 H ) , 2 . 37 ( s , 3 H ) , 3 . 40 - 3 . 49 ( m , 2 H ) , 3 . 99 - 4 . 08 ( m , 1 H ) , 4 . 94 ( t , 1 H ) , 7 . 34 ( d , 2 H ) , 7 . 60 - 7 . 65 ( m , 1 H ) , 7 . 86 ( d , 2 H ) , 8 . 16 ( ddd , 1 H ) , 8 . 64 ( s , 1 H ) , 8 . 68 ( dd , 1 H ) , 8 . 90 ( d , 1 H ) , 9 . 44 ( d , 1 H ) .