The photochemistry of the 4-pyrimidinones lb-1 in liquid NH,-ether solution at-40" C or in methanol at-10 to-40" C was studied. Irradiation of lb-g at low temperature gave the corresponding Dewar 4-pyrimidinones (2b-g), whose physical properties (IR, NMR, and UV) were determined. The photolysis of lh-j in methanol at-10 to-20 OC gave methanol adducts 5- 7 which suggested the formation of the Dewar 4-pyrimidinones 2h-j. However, the ...
