1 H NMR ( 300 MHz , DMSO - d 6 ) δ 2 . 30 ( 3 H , s ) , 3 . 40 - 3 . 50 ( 2 H , m ) , 4 . 60 - 4 . 70 ( 2 H , m ) , 6 . 70 ( 1 H , t , J = 7 . 0 Hz ) , 6 . 92 - 7 . 04 ( 2 H , m ) , 7 . 27 ( 1 H , s ) , 7 . 47 - 7 . 66 ( 5 H , m ) , 7 . 77 ( 1 H , dd , J = 6 . 6 , 1 . 7 Hz ) .