1 H NMR ( 300 MHz , DMSO - d 6 ) δ 0 . 73 - 0 . 93 ( 2 H , m ) , 0 . 93 - 1 . 07 ( 2 H , m ) , 1 . 68 - 1 . 91 ( 4 H , m ) , 1 . 99 - 2 . 14 ( 1 H , m ) , 3 . 26 - 3 . 29 ( 2 H , m ) , 3 . 44 - 3 . 60 ( 2 H , m ) , 3 . 76 - 4 . 01 ( 3 H , m ) , 6 . 62 ( 1 H , s ) , 7 . 42 ( 2 H , d , J = 8 . 3 Hz ) , 7 . 60 ( 2 H , d , J = 8 . 7 Hz ) .