Catalyst-free intramolecular radical cyclization cascades initiated by the direct homolysis of C-Br under visible light

• Published in: Green chemistry : an international journal and green chemistry resource : GC 2023-05, Vol.25 (1), p.3989-3994
• Main Authors: Huang, Panyi, Yan, Zhiyang, Ling, Jiaxin, Li, Peixuan, Wang, Jiayang, Li, Jianjun, Sun, Bin, Jin, Can
• Format: Article
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d3gc00304c

A visible light-driven carbon-carbon bond-forming cyclization cascade under metal- and catalyst-free conditions has been reported. The cascade is initiated through a transient alkyl radical intermediate that is formed by the direct homolysis of C sp 3 -Br under visible light, affording a series of 3-substituted chroman-4-ones. Crucially, this work exhibited a facile and effective strategy for building three-dimensional polycyclic compounds using two-dimensional long-chain compounds as building blocks. The protocol has significant advantages such as high diastereoselectivity, high regioselectivity, metal- and catalyst-free, mild reaction conditions, controllable synthesis, and operational simplicity. A visible light-mediated C sp 3 -Br homolysis-initiated radical cyclization cascade delivering diverse 3-difluorolactam substituted chroman-4-ones with excellent regioselectivity and diastereoselectivity.