1 H NMR ( 300 MHz , DMSO - d 6 ) δ 3 . 42 - 3 . 49 ( 2 H , m ) , 4 . 61 - 4 . 68 ( 2 H , m ) , 6 . 67 - 6 . 73 ( 1 H , m ) , 7 . 00 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 10 - 7 . 30 ( 4 H , m ) , 7 . 53 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 62 ( 1 H , dd , J = 7 . 2 , 1 . 5 Hz ) , 7 . 73 - 7 . 81 ( 1 H , m ) .