1 H NMR ( 300 MHz , DMSO - d 6 ) δ 2 . 35 ( 3 H , s ) , 3 . 41 - 3 . 51 ( 2 H , m ) , 4 . 58 - 4 . 73 ( 2 H , m ) , 6 . 72 ( 1 H , t , J = 7 . 0 Hz ) , 7 . 27 - 7 . 36 ( 2 H , m ) , 7 . 44 ( 2 H , d , J = 8 . 3 Hz ) , 7 . 49 - 7 . 58 ( 2 H , m ) , 7 . 59 - 7 . 70 ( 3 H , m ) , 7 . 80 ( 1 H , dd , J = 6 . 8 , 1 . 5 Hz ) .