1 H NMR ( 400 MHz , DMSO - d 6 ) δ [ ppm ] = 3 . 15 - 3 . 32 ( m , 2 H ) , 3 . 65 - 3 . 69 ( m , 3 H ) , 3 . 77 ( dd , 1 H ) , 7 . 08 ( t , 1 H ) , 7 . 63 ( d , 2 H ) , 7 . 89 ( d , 2 H ) , 11 . 36 ( s , 1 H ) .