Ring cleavage of cyclic ester dienelactone to produce maleylacetate. 2-(5-oxo-2,5-dihydrofuran-2-ylidene)acetate + H2O = 4-oxohex-2-enedioate + H(+) Aromatic compound metabolism; 3-chlorocatechol degradation. Belongs to the dienelactone hydrolase family.