Metal-Free Photoinduced Hydrocyclization of Unactivated Alkenes toward Ring-Fused Quinazolin-4(3H)-ones via Intermolecular Hydrogen Atom Transfer

A visible-light-induced hydrocyclization of unactivated alkenes was developed using 3CzClIPN as the photocatalyst to generate substituted alpha-methyldeoxyvasicinones and alpha-methylmackinazolinones in moderate to good yields. An intermolecular hydrogen atom transfer with THF as the hydrogen source was involved. Mechanism studies indicated that the intramolecular addition of the in situ formed aminal radical to the unactivated alkene generated the polycyclic quinazolinone.

Automated summary

A visible-light-induced hydrocyclization of unactivated alkenes was achieved using 3CzClIPN as the photocatalyst, leading to the formation of substituted alpha-methyldeoxyvasicinones and alpha-methylmackinazolinones in moderate to good yields. The reaction involves an intermolecular hydrogen atom transfer with THF as the hydrogen source. Mechanistic studies revealed that the in situ formed aminal radical undergoes intramolecular addition to the unactivated alkene, resulting in the formation of a polycyclic quinazolinone.