1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 61 - 1 . 82 ( 3 H , m ) , 1 . 86 - 2 . 12 ( 4 H , m ) , 3 . 23 - 3 . 29 ( 2 H , m ) , 3 . 38 - 3 . 58 ( 2 H , m ) , 3 . 69 - 3 . 91 ( 3 H , m ) , 6 . 95 - 7 . 12 ( 4 H , m ) , 7 . 25 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 57 ( 2 H , d , J = 8 . 7 Hz ) .