1 H NMR ( 300 MHz , DMSO - d 6 ) δ 0 . 92 ( 6 H , t , J = 7 . 4 Hz ) , 1 . 51 - 1 . 76 ( 4 H , m ) , 3 . 38 - 3 . 55 ( 2 H , m ) , 4 . 17 - 4 . 37 ( 1 H , m ) , 4 . 55 - 4 . 73 ( 2 H , m ) , 6 . 69 ( 1 H , t , J = 7 . 0 Hz ) , 6 . 87 - 7 . 02 ( 2 H , m ) , 7 . 37 - 7 . 51 ( 2 H , m ) , 7 . 59 ( 1 H , d , J = 7 . 2 Hz ) , 7 . 74 ( 1 H , d , J = 6 . 8 Hz ) .