1 H NMR ( 400 MHz , DMSO - d 6 ) δ ppm = 1 . 10 ( s , 3 H ) , 1 . 13 ( d , 3 H ) , 1 . 15 ( s , 3 H ) , 3 . 85 - 3 . 97 ( m , 1 H ) , 4 . 64 ( s , 1 H ) , 7 . 42 - 7 . 56 ( m , 2 H ) , 7 . 97 - 8 . 09 ( m , 2 H ) , 8 . 55 ( s , 1 H ) , 9 . 75 ( br d , 1 H ) , 14 . 02 ( br s , 1 H ) .