2-Oxopyran-5-carboxylic acid 2-Pentenedioic acid, 4-(hydroxymethylene)-, delta-lactone 2H-Pyran-5-carboxylic acid, 2-oxo- 500-05-0 Coumalic acid Cumalic acid EINECS 207-899-0 NSC 22978 alpha-Pyrone-5-carboxylic acid