1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 62 - 1 . 85 ( 3 H , m ) , 1 . 89 - 2 . 10 ( 1 H , m ) , 3 . 25 - 3 . 28 ( 2 H , m ) , 3 . 41 - 3 . 56 ( 2 H , m ) , 3 . 69 - 3 . 89 ( 3 H , m ) , 6 . 92 - 7 . 09 ( 4 H , m ) , 7 . 23 ( 2 H , d , J = 8 . 3 Hz ) , 7 . 38 - 7 . 48 ( 2 H , m ) .