The molecule is dianion of (2E)-2-(methoxycarbonylmethyl)but-2-enedioic acid arising from deprotonation of both carboxylic acid functions. It is a conjugate base of a (2E)-2-(methoxycarbonylmethyl)but-2-enedioic acid.
(E)-2-(2-methoxy-2-oxoethyl)but-2-enedioate