2-Azabutadienes are formed in quantitative yield by flash vacuum pyrolysis of oxazol-5(2H)-ones, but partially decompose owing to chemical activation when generated from 2H-azirines.
imines or pyrrole compounds. Harnessing the power of photocatalysis, we accomplished a straightforward synthesis of 3-oxazolin-5-ones from redox-active esters and secondary nitrocompounds. Visible light-induced nondecarboxylative coupling of a redox-active ester, nitro aldol condensation, and subsequent visible light-induced N-oxide deoxygenation were accomplished within 2 h. The reaction mechanism was