1 H 　 NMR ( DMSO - d 6 , 400 MHz ) δ 10 . 33 ( s , 1 H ) , 9 . 65 ( s , 1 H ) , 9 . 15 ( s , 1 H ) , 7 . 77 ( br , 2 H ) , 7 . 67 ( s , 1 H ) , 7 . 00 ( d , J = 8 Hz , 2 H ) , 6 . 85 ( d , J = 4 Hz , 1 H ) , 6 . 76 ( dJ = 4 Hz , 1 H ) , 3 . 92 ( s , 3 H ) , 3 . 81 ( s , 3 H ) , 3 . 72 ( br , 1 H ) , 3 . 12 ( t , J = 6 Hz , 4 H ) , 2 . 97 ( t , J = 6 Hz , 4 H ) .