1 H - NMR ( 400 MHz , DMSO - D 6 ) δ : 1 . 15 ( 6 H , s ) , 3 . 77 ( 2 H , s ) , 4 . 67 ( 1 H , s ) , 7 . 10 ( 1 H , d , J = 7 . 9 Hz ) , 7 . 42 ( 1 H , dd , J = 7 . 9 , 1 . 8 Hz ) , 7 . 71 ( 1 H , d , J = 1 . 8 Hz ) , 7 . 95 ( 1 H , d , J = 8 . 5 Hz ) , 8 . 29 ( 1 H , dd , J = 8 . 5 , 2 . 4 Hz ) , 9 . 05 ( 1 H , d , J = 2 . 4 Hz ) , 11 . 05 ( 1 H , s ) .