UV-induced photochemistry of methyl coumalate (methyl 2-pyrone-5-carboxylate) isolated in low-temperature inert matrices

UV-induced photochemistry of monomeric methyl coumalate (5-substituted analogue of α-pyrone, R = COOCH3) isolated in low temperature matrices has been studied. Two observed photoreactions (isomerisation to Dewar analogue and ring-opening) were found to be reversible. Moreover, the Dewar analogue underwent decarboxylation resulting in production of antiaromatic substituted cyclobutadiene derivative.