1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 65 - 1 . 84 ( 3 H , m ) , 1 . 92 - 2 . 10 ( 1 H , m ) , 2 . 28 ( 3 H , s ) , 3 . 23 - 3 . 29 ( 2 H , m ) , 3 . 41 - 3 . 55 ( 2 H , m ) , 3 . 70 - 3 . 90 ( 3 H , m ) , 6 . 84 - 6 . 96 ( 2 H , m , J = 8 . 7 Hz ) , 7 . 11 - 7 . 29 ( 3 H , m ) , 7 . 42 - 7 . 51 ( 1 H , m ) , 7 . 57 ( 1 H , d , J = 7 . 9 Hz ) .