Visible-light-induced intramolecular charge transfer in the radical spirocyclisation of indole-tethered ynones

Hon Eong Ho, Angela Pagano, James A. Rossi-Ashton, James R. Donald, Ryan G. Epton, Jonathan C. Churchill, Michael J. James, Peter O'Brien, Richard J.K. Taylor*, William P. Unsworth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Indole-tethered ynones form an intramolecular electron donor-acceptor complex that can undergo visible-light-induced charge transfer to promote thiyl radical generation from thiols. This initiates a novel radical chain sequence, based on dearomatising spirocyclisation with concomitant C-S bond formation. Sulfur-containing spirocycles are formed in high yields using this simple and mild synthetic protocol, in which neither transition metal catalysts nor photocatalysts are required. The proposed mechanism is supported by various mechanistic studies, and the unusual radical initiation mode represents only the second report of the use of an intramolecular electron donor-acceptor complex in synthesis.

Original languageEnglish
Pages (from-to)1353-1360
Number of pages8
JournalChemical Science
Issue number5
Early online date13 Dec 2019
Publication statusPublished - 7 Feb 2020

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© The Royal Society of Chemistry 2020

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