1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 64 - 1 . 80 ( 3 H , m ) , 1 . 89 - 2 . 06 ( 1 H , m ) , 2 . 17 ( 3 H , s ) , 3 . 27 ( 2 H , t , J = 6 . 4 Hz ) , 3 . 37 - 3 . 54 ( 2 H , m ) , 3 . 69 - 3 . 88 ( 3 H , m ) , 6 . 73 - 6 . 84 ( 2 H , m ) , 6 . 92 - 7 . 10 ( 2 H , m ) , 7 . 13 - 7 . 25 ( 3 H , m ) .