1 H - NMR ( 400 MHz , DMSO - D 6 ) δ : 3 . 70 ( 3 H , s ) , 4 . 15 ( 2 H , s ) , 4 . 44 ( 2 H , d , J = 6 . 8 Hz ) , 4 . 601 ( 2 H , d , J = 6 . 8 Hz ) , 6 . 09 ( 1 H , s ) , 6 . 63 ( 1 H , d , J = 2 . 4 Hz ) , 6 . 73 ( 1 H , dd , J = 8 . 8 , 2 . 4 Hz ) , 7 . 26 ( 1 H , d , J = 8 . 8 Hz ) , 7 . 56 ( 2 H , d , J = 8 . 4 Hz ) , 7 . 70 - 7 . 72 ( 2 H , m ) .