1 H NMR ( 400 MHz , DMSO - d 6 ) : δ [ ppm ] = 1 . 17 ( d , 3 H ) , 3 . 40 - 3 . 50 ( m , 2 H ) , 3 . 99 - 4 . 10 ( m , 1 H ) , 4 . 95 ( t , 1 H ) , 7 . 64 ( ddd , 1 H ) , 7 . 89 ( d , 2 H ) , 8 . 18 ( ddd , 1 H ) , 8 . 21 ( d , 2 H ) , 8 . 70 ( dd , 1 H ) , 8 . 73 ( s , 1 H ) , 8 . 92 ( d , 1 H ) , 9 . 39 ( d , 1 H ) .