Photocatalytic [4 + 1] Cycloaddition Access to Multisubstituted 2-Imino-2,5-dihydrofurans

Isocyanide radical cyclization, typically restricted to aryl isocyanides, is hampered by complex radical precursors. We've developed a strategy that overcomes this constraint by integrating [4 + 1] cyclization with a multifunctional system, which extends to alkyl and biomolecule-derived isocyanides and achieves a rare 1,2,3,4-tetrasubstitution of α,β-unsaturated carbonyls. Over 50 2-imino-2,5-dihydrofuran derivatives have been synthesized, allowing for molecular skeleton editing into valuable frameworks. These derivatives show antitumor activity, indicating their potential in drug development.