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Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition

The [2+2] photocycloaddition is the most valuable and intensively investigated photochemical process. Here we demonstrate that irradiation of N‐acryloyl heterocycles with blue LED light (440 nm) in the presence of an Ir(III) complex leads to efficient and high yielding fused γ‐lactam formation acros...

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Autores principales: Popescu, Mihai V., Mekereeya, Aroonroj, Alegre‐Requena, Juan V., Paton, Robert S., Smith, Martin D.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891567/
https://www.ncbi.nlm.nih.gov/pubmed/32856748
http://dx.doi.org/10.1002/anie.202009704
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author Popescu, Mihai V.
Mekereeya, Aroonroj
Alegre‐Requena, Juan V.
Paton, Robert S.
Smith, Martin D.
author_facet Popescu, Mihai V.
Mekereeya, Aroonroj
Alegre‐Requena, Juan V.
Paton, Robert S.
Smith, Martin D.
author_sort Popescu, Mihai V.
collection PubMed
description The [2+2] photocycloaddition is the most valuable and intensively investigated photochemical process. Here we demonstrate that irradiation of N‐acryloyl heterocycles with blue LED light (440 nm) in the presence of an Ir(III) complex leads to efficient and high yielding fused γ‐lactam formation across a range of substituted heterocycles. Quantum calculations show that the reaction proceeds via cyclization in the triplet excited state to yield a 1,4‐diradical; intersystem crossing leads preferentially to the closed shell singlet zwitterion. This is geometrically restricted from undergoing recombination to yield a cyclobutane by the planarity of the amide substituent. A prototropic shift leads to the observed bicyclic products in what can be viewed as an interrupted [2+2] cycloaddition.
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spelling pubmed-78915672021-03-02 Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition Popescu, Mihai V. Mekereeya, Aroonroj Alegre‐Requena, Juan V. Paton, Robert S. Smith, Martin D. Angew Chem Int Ed Engl Communications The [2+2] photocycloaddition is the most valuable and intensively investigated photochemical process. Here we demonstrate that irradiation of N‐acryloyl heterocycles with blue LED light (440 nm) in the presence of an Ir(III) complex leads to efficient and high yielding fused γ‐lactam formation across a range of substituted heterocycles. Quantum calculations show that the reaction proceeds via cyclization in the triplet excited state to yield a 1,4‐diradical; intersystem crossing leads preferentially to the closed shell singlet zwitterion. This is geometrically restricted from undergoing recombination to yield a cyclobutane by the planarity of the amide substituent. A prototropic shift leads to the observed bicyclic products in what can be viewed as an interrupted [2+2] cycloaddition. John Wiley and Sons Inc. 2020-10-08 2020-12-14 /pmc/articles/PMC7891567/ /pubmed/32856748 http://dx.doi.org/10.1002/anie.202009704 Text en © 2020 The Authors. Published by Wiley-VCH GmbH This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Communications
Popescu, Mihai V.
Mekereeya, Aroonroj
Alegre‐Requena, Juan V.
Paton, Robert S.
Smith, Martin D.
Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title_full Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title_fullStr Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title_full_unstemmed Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title_short Visible‐Light‐Mediated Heterocycle Functionalization via Geometrically Interrupted [2+2] Cycloaddition
title_sort visible‐light‐mediated heterocycle functionalization via geometrically interrupted [2+2] cycloaddition
topic Communications
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891567/
https://www.ncbi.nlm.nih.gov/pubmed/32856748
http://dx.doi.org/10.1002/anie.202009704
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