1 H - NMR : ( 300 MHz , DMSO - d 6 ) δ 11 . 40 ( s , 1 H ) , 9 . 88 ( s , 1 H ) , 8 . 21 ( s , 1 H ) , 7 . 41 ( dd , 1 H , J = 2 . 25 Hz ) , 7 . 29 ( m , 2 H , J = 5 . 67 Hz , 7 . 35 Hz ) , 6 . 05 ( s , 1 H ) , 4 . 22 ( d , 2 H , J = 12 . 6 ) , 3 . 60 ( s , 3 H ) , 2 . 88 ( t , 2 H , 12 . 45 Hz ) , 2 . 40 ( s , 3 H ) , 2 . 27 ( d , 2 H , J = 6 . 93 Hz ) , 2 . 24 ( s , 3 H ) , 1 . 99 ( broad , 1 H ) , 1 . 75 ( d , 2 H , J = 8 . 3 Hz ) , 1 . 11 ( m , 2 H )