1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 70 - 1 . 82 ( 3 H , m ) , 1 . 95 - 2 . 09 ( 1 H , m ) , 3 . 26 - 3 . 29 ( 2 H , m ) , 3 . 39 - 3 . 55 ( 2 H , m ) , 3 . 75 - 3 . 87 ( 3 H , m ) , 7 . 03 - 7 . 18 ( 4 H , m ) , 7 . 29 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 74 ( 2 H , d , J = 8 . 7 Hz ) .