1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 64 - 1 . 85 ( 3 H , m ) , 1 . 88 - 2 . 10 ( 1 H , m , J = 6 . 0 Hz ) , 3 . 23 - 3 . 29 ( 2 H , m ) , 3 . 38 - 3 . 57 ( 2 H , m ) , 3 . 71 - 3 . 91 ( 3 H , m ) , 6 . 94 - 7 . 10 ( 3 H , m ) , 7 . 18 - 7 . 34 ( 3 H , m ) , 7 . 44 ( 1 H , t , J = 9 . 1 Hz ) .