Issue 30, 2024

Charge-recombinative triplet sensitization of alkenes for DeMayo-type [2 + 2] cycloaddition

Abstract

Synthetic photochemistry has undergone significant development, largely owing to the development of visible-light-absorbing photocatalysts (PCs). PCs have significantly improved the efficiency and precision of cycloaddition reactions, primarily through energy or electron transfer pathways. Recent research has identified photocatalysis that does not follow energy- or electron-transfer formalisms, indicating the existence of other, undiscovered photoactivation pathways. This study unveils an alternative route: a charge-neutral photocatalytic process called charge-recombinative triplet sensitization (CRTS), a mechanism with limited precedents in synthetic chemistry. Our investigations revealed CRTS occurrence in DeMayo-type [2 + 2] cycloaddition reactions catalyzed by indole-fused organoPCs. Our mechanistic investigations, including steady-state and transient spectroscopic analyses, electrochemical investigations, and quantum chemical calculations, suggest a mechanism involving substrate activation through photoinduced electron transfer, followed by charge recombination, leading to substrate triplet state formation. Our findings provide valuable insights into the underlying photocatalytic reaction mechanisms and pave the way for the systematic design and realization of innovative photochemical processes.

Graphical abstract: Charge-recombinative triplet sensitization of alkenes for DeMayo-type [2 + 2] cycloaddition

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Article information

Article type
Edge Article
Submitted
19 Apr 2024
Accepted
27 Jun 2024
First published
28 Jun 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2024,15, 12058-12066

Charge-recombinative triplet sensitization of alkenes for DeMayo-type [2 + 2] cycloaddition

Y. Lee, B. H. Jhun, S. Woo, S. Kim, J. Bae, Y. You and E. J. Cho, Chem. Sci., 2024, 15, 12058 DOI: 10.1039/D4SC02601B

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