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Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis
Heterogeneous semiconductor photoredox catalysis (SCPC), particularly with TiO(2), is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i) interact with a precursor that donates an electron to the semiconductor thus generating a...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Beilstein-Institut
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4660884/ https://www.ncbi.nlm.nih.gov/pubmed/26664577 http://dx.doi.org/10.3762/bjoc.11.173 |
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author | Manley, David W Walton, John C |
author_facet | Manley, David W Walton, John C |
author_sort | Manley, David W |
collection | PubMed |
description | Heterogeneous semiconductor photoredox catalysis (SCPC), particularly with TiO(2), is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i) interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii) interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas. |
format | Online Article Text |
id | pubmed-4660884 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Beilstein-Institut |
record_format | MEDLINE/PubMed |
spelling | pubmed-46608842015-12-09 Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis Manley, David W Walton, John C Beilstein J Org Chem Review Heterogeneous semiconductor photoredox catalysis (SCPC), particularly with TiO(2), is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i) interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii) interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas. Beilstein-Institut 2015-09-09 /pmc/articles/PMC4660884/ /pubmed/26664577 http://dx.doi.org/10.3762/bjoc.11.173 Text en Copyright © 2015, Manley and Walton https://creativecommons.org/licenses/by/2.0https://www.beilstein-journals.org/bjoc/termsThis is an Open Access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (https://www.beilstein-journals.org/bjoc/terms) |
spellingShingle | Review Manley, David W Walton, John C Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title | Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title_full | Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title_fullStr | Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title_full_unstemmed | Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title_short | Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis |
title_sort | preparative semiconductor photoredox catalysis: an emerging theme in organic synthesis |
topic | Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4660884/ https://www.ncbi.nlm.nih.gov/pubmed/26664577 http://dx.doi.org/10.3762/bjoc.11.173 |
work_keys_str_mv | AT manleydavidw preparativesemiconductorphotoredoxcatalysisanemergingthemeinorganicsynthesis AT waltonjohnc preparativesemiconductorphotoredoxcatalysisanemergingthemeinorganicsynthesis |