1 H NMR ( 400 MHz , DMSO - d 6 ) δ [ ppm ] = 1 . 16 ( d , 3 H ) , 3 . 42 - 3 . 50 ( m , 2 H ) , 3 . 99 - 4 . 09 ( m , 1 H ) , 4 . 95 ( t , 1 H ) , 7 . 51 ( d , 2 H ) , 7 . 63 ( dd , 1 H ) , 8 . 09 - 8 . 14 ( m , 2 H ) , 8 . 17 ( ddd , 1 H ) , 8 . 67 - 8 . 71 ( m , 2 H ) , 8 . 91 ( d , 1 H ) , 9 . 41 ( d , 1 H ) .