1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 68 - 1 . 80 ( 3 H , m ) , 1 . 91 - 2 . 09 ( 1 H , m ) , 2 . 18 ( 3 H , s ) , 3 . 25 - 3 . 29 ( 2 H , m ) , 3 . 47 ( 2 H , q , J = 5 . 7 Hz ) , 3 . 70 - 3 . 86 ( 3 H , m ) , 6 . 82 ( 2 H , d , J = 8 . 7 Hz ) , 6 . 91 ( 1 H , d , J = 7 . 6 Hz ) , 7 . 06 - 7 . 25 ( 4 H , m ) , 7 . 32 ( 1 H , dd , J = 7 . 4 , 0 . 9 Hz ) .