Photochemistry of 1,3-dimethyluracil: a novel photochemical ring-opening leading to an enamine

Abstract Besides known reduction and solvent addition products, the photolysis of 1,3-dimethyluracil in methanol resulted in formation of the enamine 2-methoxycarbonyl-N-methyl-3-methylaminopropenamide (5) via a novel ring-opening reaction. A mechanism for the formation of 5 is suggested and its structure was confirmed by an independent synthesis.