1 H NMR ( 300 MHz , DMSO - d 6 ) δ 0 . 91 ( 6 H , d , J = 6 . 8 Hz ) , 2 . 04 - 2 . 27 ( 1 H , m ) , 3 . 88 ( 2 H , d , J = 7 . 2 Hz ) , 6 . 42 ( 1 H , d , J = 2 . 6 Hz ) , 7 . 07 ( 1 H , d , J = 3 . 0 Hz ) , 7 . 16 - 7 . 22 ( 1 H , m ) , 7 . 24 - 7 . 25 ( 1 H , m ) , 7 . 74 ( 1 H , d , J = 1 . 5 Hz ) .