1 H NMR ( 300 MHz , DMSO - d 6 ) δ : 8 . 00 ( d , J = 7 . 7 Hz , 1 H ) , 7 . 68 - 7 . 61 ( m , 5 H ) , 7 . 53 - 7 . 45 ( m , 2 H ) , 6 . 73 ( d , J = 7 . 5 Hz , 1 H ) , 4 . 98 ( m , 1 H ) , 1 . 36 ( d , J = 6 . 2 Hz , 6 H ) .