Photochemical Divergent Ring-Closing Metathesis of 1,7-Enynes: Efficient Synthesis of Spirocyclic Quinolin-2-ones

Org Lett. 2024 Aug 9;26(31):6664-6669. doi: 10.1021/acs.orglett.4c02332. Epub 2024 Jul 30.

Abstract

A photocatalytic method for the ring-closing 1,7-enyne metathesis using the α-amino radical as an alkene deconstruction auxiliary is present. Preliminary mechanistic studies suggest that intramolecular 1,5-hydrogen atom transfer is the key to the generation and β-scission of the α-amino radical, while the dearomatization of arenes and ring opening of cyclopropanes are the key to construct spirocyclic quinolin-2-ones. This approach highlights the potential of ring-closing 1,7-enyne metathesis, providing a green, efficient, and step-economical way for the synthesis of spirocyclic quinolin-2-ones.