1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 63 - 1 . 85 ( 3 H , m ) , 1 . 93 - 2 . 08 ( 1 H , m ) , 3 . 22 - 3 . 28 ( 2 H , m ) , 3 . 39 - 3 . 56 ( 2 H , m ) , 3 . 74 - 3 . 89 ( 6 H , m ) , 6 . 51 ( 1 H , dd , J = 8 . 7 , 2 . 7 Hz ) , 6 . 91 ( 1 H , d , J = 2 . 7 Hz ) , 6 . 98 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 23 ( 2 H , d , J = 8 . 7 Hz ) , 7 . 39 ( 1 H , d , J = 8 . 7 Hz ) .