1 H NMR ( 400 MHz , DMSO - d 6 ) δ 10 . 03 ( s , 1 H ) , 8 . 43 - 8 . 40 ( m , 1 H ) , 7 . 68 ( t , J = 9 . 2 Hz , 1 H ) , 7 . 27 ( d , J = 8 . 4 Hz , 1 H ) , 7 . 06 ( d , J = 8 . 4 Hz , 1 H ) , 5 . 80 ( dd , J = 10 . 4 , 3 . 6 Hz , 1 H ) , 4 . 36 - 4 . 31 ( m , 1 H ) , 4 . 24 - 4 . 13 ( m , 3 H ) , 3 . 77 ( s , 3 H ) , 3 . 10 ( s , 3 H ) , 2 . 00 - 1 . 97 ( m , 1 H ) , 1 . 20 ( t , J = 7 . 2 Hz , 3 H ) , 0 . 87 ( d , J = 5 . 2 Hz , 4 H ) . LCMS : [ M + H ] + = 506 . 2 .