Enantioselective Aminocatalytic [2 + 2] Cycloaddition through Visible Light Excitation

Rigotti, Thomas; Mas-Ballesté, Rubén; Alemán, José

UAM_Biblioteca

Author

Rigotti, Thomas; Mas-Ballesté, Rubén; Alemán, José

Entity

UAM. Departamento de Química Inorgánica; UAM. Departamento de Química Orgánica

Publisher

American Chemistry Society

Date

2020-05-01

Citation

ACS Catalysis 10.9 (2020): 5335-5346

ISSN

2155-5435

DOI

10.1021/acscatal.0c01413

Funded by

Financial support was provided by the European Research Council (ERC-CoG, Contract No. 647550), the Spanish Government (RTI2018-095038–B-I00), “Comunidad de Madrid”, and European Structural Funds (S2018/NMT-4367)

Project

Gobierno de España. RTI2018-095038–B-I00; Comunidad de Madrid. S2018/NMT-4367; info:eu-repo/grantAgreement/EC/H2020/647550/EU//UNBICAT

Editor's Version

https://doi.org/10.1021/acscatal.0c01413

Subjects

Photocatalysis; Enantioselective [2+2] photocycloaddition; Iminium ion catalysis; Charge transfer complex; EDA complex photoactivity; Cyclobutanes; Aminocatalysis; Química

URI

http://hdl.handle.net/10486/690972

Note

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: https://pubs.acs.org/doi/full/10.1021/acscatal.0c01413

Rights

Abstract

An asymmetric aminocatalytic activation strategy to obtain enantioenriched cyclobutanes through [2 + 2] photocycloaddition under visible light irradiation is presented. This metal-free process does not require the use of any external photocatalyst, as it is catalyzed by a simple diamine which, upon condensation with an enone substrate, forms an iminium ion intermediate that absorbs in the visible light region. The direct excitation of such an intermediate leads to a charge transfer (CT) excited state that unlocks a stereocontrolled intermolecular photocycloaddition with good enantiomeric and diastereoisomeric ratios and high yields. Finally, DFT calculations and experiments were performed to support the charge transfer behavior and the mechanistic proposal

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