A new regioselective synthesis and ambient light photochemistry of quinazolin-1-oxides

Quinazolin-1-oxides were prepared by the oxidation of tetrahydroquinazolines with H2O2–tungstate and their ambient light photochemistry was investigated. Substituent effects on their photochemical cyclization and the reactions of the products 1aH-[1,2]oxazireno[2,3-a]quinazolines under photochemical and thermal conditions are reported. The cyclization of quinazolin-1-oxides and the reactions of 1aH-[1,2]oxazireno[2,3-a]quinazolines show pronounced solvent isotope and solvent effects.