Photocatalytic [3+2] Cycloaddition of Alkyl/aryl Iodides and Internal Alkynes by Merging Halogen and Hydrogen Atom Transfer
Zhenyu Gu , Rong Jia , Tianqing Zeng , Hanliang Zheng , Gangguo Zhu
Chinese Journal of Chemistry ›› 2024, Vol. 42 ›› Issue (19) : 2329 -2334.
Photocatalytic [3+2] Cycloaddition of Alkyl/aryl Iodides and Internal Alkynes by Merging Halogen and Hydrogen Atom Transfer
A visible light photocatalytic [3+2] cycloaddition of alkynes with readily accessible organic iodides as the C3 synthon is developed herein. By merging halogen atom transfer (XAT) and hydrogen atom transfer (HAT), alkyl/aryl iodides serve as a formal diradical precursor and add across C-C triple bonds to deliver a number of functionalized cyclopentanes in moderate to high yields with exceptional regio- and diastereoselectivity. A reductive radical-polar crossover mechanism, involving the cascade XAT, radical addition, 1, 5-HAT, polar effect-promoted 5-endo annulation, single electron transfer (SET) reduction, and protonation, may account for this unprecedented dehalogenative [3+2] cycloaddition. This work not only expands the repertoire of the traditional RATC methodology, but also provides a robust platform for the expedient assembly of cyclopentanes, a valuable structural motif in the realms of medicinal chemistry and material sciences.
Photocatalysis / Halogen atom transfer / Hydrogen atom transfer / [3+2] cycloaddition / Cyclopentane / Carbocycles / Radical reactions / Diastereoselectivity
2024 SIOC, CAS, Shanghai, & WILEY-VCH GmbH.
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