Volume 28, Issue 65 e202202018
Research Article

Design of a Photocatalytic [2+2] Cycloaddition Reaction Using Redox-Tag Strategy

Yasuhiro Hashimoto

Yasuhiro Hashimoto

Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, 184-8588 Koganei, Tokyo, Japan

Search for more papers by this author
Dr. Genki Horiguchi

Dr. Genki Horiguchi

Energy Catalyst Technology Group, Energy Process Research Institute (EPRI), National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, 305-8559 Tsukuba, Ibaraki, Japan

Search for more papers by this author
Prof. Dr. Hidehiro Kamiya

Prof. Dr. Hidehiro Kamiya

Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, 184-8588 Koganei, Tokyo, Japan

Search for more papers by this author
Prof. Dr. Yohei Okada

Corresponding Author

Prof. Dr. Yohei Okada

Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, 183-8509 Fuchu, Tokyo, Japan

Search for more papers by this author
First published: 24 August 2022
Citations: 3

Graphical Abstract

A new photocatalytic [2+2] cycloaddition reaction based on our Redox-Tag strategy was developed involving carefully designed substrates which turned out to be effective for the reaction. A radical cation was formed by oxidative single electron transfer (SET) that immediately reacted with an alkene. An aryl radical cation was generated by intramolecular SET and during the subsequent reductive SET a cyclobutane was formed.

Abstract

The design of photocatalytic processes is important for a sustainable society. Key to these photocatalytic reactions is electron transfer. This article is focused on titanium dioxide photocatalyzed organic synthesis and the design of a new [2+2] cycloaddition reaction based on the electron transfer process. Electron transfer - not only between the substrate and the photocatalyst but also inter- and intramolecularly – is crucial for the reaction design. Radical cations were generated by the photocatalyst and trapped by alkenes. The resultant cyclobutyl radical cations were immediately reduced by the aryl rings via intramolecular electron transfer to obtain cyclobutane rings. The outcome of the reaction was controlled by substitution of the aryl ring and the linker connecting the aryl ring to the enol ether. The carefully designed substrates were highly effective for photocatalytic cycloaddition.

Conflict of interest

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available in the supplementary material of this article.