1 H NMR ( 400 MHz , DMSO - d 6 ) : δ 9 . 71 ( s , 1 H ) , 8 . 47 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 80 - 7 . 84 ( m , 1 H ) , 7 . 60 ( d , J = 7 . 2 Hz , 1 H ) , 7 . 27 ( d , J = 8 . 0 Hz , 1 H ) , 7 . 02 ( d , J = 8 . 0 Hz , 1 H ) , 5 . 81 ( dd , J = 10 . 8 , 4 . 0 Hz , 1 H ) , 4 . 30 - 4 . 34 ( m , 1 H ) , 4 . 15 - 4 . 22 ( m , . 3 H ) , 3 . 76 ( s , 3 H ) , 3 . 09 ( s , 3 H ) , 2 . 18 ( s , 3 H ) , 1 . 17 ( dd , J = 7 . 2 Hz , 3 H ) . LCMS : [ ( M + 1 ) ] + = 462 . 0 .