Photochemistry of Pyrimidin-2(1H)-ones: Intramolecular γ-Hydrogen Abstraction by the Nitrogen of the Imino Group

Article abstract of DOI:10.1039/P19860001147

Irradiation of 1-aryl-4-propyl- (1a) and 1-aryl-4-(3-ethoxypropyl)-6-methylpyrimidin-2(1H)-ones (1b-d) gave the photoelimination products, 1-aryl-4,6-dimethylpyrimidin-2(1H)-ones (2a-d), via intramolecular γ-hydrogen atom abstraction of the excited imino nitrogen of the starting pyrimidin-2(1H)-one (1), in addition to the 1,3-diazabicyclo<2.2.0>hex-5-en-2-ones (3a-d).The pyrimidin-2(1H)-ones (1f) and (1h), which have no γ-hydrogens at the C-4 position, underwent photochemical electrocyclization to give the 1,3-diazabicyclo<2.2.0>hex-5-en-2-ones (3f) and (3h) as the sole products.