1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 64 - 1 . 83 ( 3 H , m ) , 1 . 85 - 2 . 09 ( 4 H , m ) , 3 . 24 - 3 . 30 ( 2 H , m ) , 3 . 39 - 3 . 61 ( 2 H , m ) , 3 . 73 - 3 . 93 ( 3 H , m ) , 7 . 32 ( 2 H , d , J = 7 . 6 Hz ) , 7 . 50 ( 2 H , d , J = 7 . 6 Hz ) .