1 H NMR ( 300 MHz , DMSO - d 6 ) δ : 8 . 42 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 61 - 7 . 52 ( m , 4 H ) , 7 . 46 - 7 . 34 ( m , 4 H ) , 7 . 26 ( s , 1 H ) , 4 . 14 ( s , 3 H ) , 3 . 78 ( t , J = 7 . 2 Hz , 2 H ) , 2 . 99 ( d , J = 20 . 9 Hz , 1 H ) , 1 . 70 - 1 . 60 ( m , 3 H ) , 0 . 98 ( d , J = 6 . 2 Hz , 6 H ) .