1 H - NMR ( 400 MHz , DMSO - D 6 ) δ : 1 . 16 ( 6 H , s ) , 3 . 76 ( 2 H , s ) , 4 . 70 ( 1 H , s ) , 7 . 08 ( 1 H , d , J = 8 . 2 Hz ) , 7 . 84 ( 1 H , dd , J = 8 . 2 , 1 . 8 Hz ) , 8 . 05 ( 1 H , d , J = 1 . 8 Hz ) , 8 . 12 ( 1 H , d , J = 8 . 5 Hz ) , 8 . 22 ( 1 H , dd , J = 8 . 5 , 1 . 8 Hz ) , 8 . 97 ( 1 H , s ) , 11 . 09 ( 1 H , s ) .