(2Z)-2-(4-chloro-5-oxofuran-2-ylidene)acetate (2Z)-2-(4-chloro-5-oxo-2-furylidene)acetate (2Z)-2-(4-chloro-5-keto-2-furylidene)acetate (2Z)-2-(4-chloro-5-oxo-furan-2-ylidene)ethanoate 2-Chlorodienelactone c0291