1
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Shin HS, Moon DY, An S, Park BS. Solvent assisted photochemical formation of a new keto[3,3]paracyclophane. Org Biomol Chem 2022; 20:4303-4308. [PMID: 35575223 DOI: 10.1039/d2ob00660j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photolysis of a phenacyl benzoate tethered with a phenol leads to a very efficient release of benzoic acid, which is suggested to occur by electron transfer and/or proton transfer from the remote phenol moiety to the triplet excited carbonyl. Photolysis of the compound in protic solvents forms a new keto[3,3]paracyclophane.
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Affiliation(s)
- Ho Suk Shin
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Da Yoon Moon
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Sejin An
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Bong Ser Park
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
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2
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Guo Y, Dai M, Phillips DL, Xu W, Ma J. Photodeprotection Reaction Mechanisms of Caged Species Utilizing a Photochromism Function. J Phys Chem Lett 2022; 13:3417-3423. [PMID: 35404609 DOI: 10.1021/acs.jpclett.2c00619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Acetoxy-1,2,2-tri(aryl)ethanone (1) is a novel and visual release-and-report system that contains the photochromic diarylethylene function attached to the photocage dimethoxybenzoin platform. However, the mechanism of 1 cyclization and a subsequent deprotection remains unclear. Here, we use femtosecond and nanosecond transient absorption spectroscopies in combination with density functional theory computations to study the detailed reaction mechanism. The photodeprotection proceeds with competition between pathways initiated by two different configurations of the singlet excited state of 1 (labeled as 11LE and 11CT); the stepwise elimination after cyclization of 11LE constitutes the predominant pathway, whereas the concerted removal of acetic acid after cyclization of 11CT is the minor pathway. These results contribute to a detailed photodeprotection mechanism of 1 and provide new insights into the effect of geometric configurations of intermediates on the photodeprotection pathways. This new information can help in the further development of this type of the photolabile protecting group (PPG) for the protection of biorelevant molecules and in the design of an improved and versatile release-and-report PPG.
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Affiliation(s)
- Yan Guo
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Mingdong Dai
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong 999077, P. R. China
| | - Wenhua Xu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Jiani Ma
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
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3
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Toriumi N, Yamashita K, Iwasawa N. Metal-Free Photoredox-Catalyzed Hydrodefluorination of Fluoroarenes Utilizing Amide Solvent as Reductant. Chemistry 2021; 27:12635-12641. [PMID: 34190366 DOI: 10.1002/chem.202101813] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Indexed: 12/15/2022]
Abstract
A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N',N'-tetramethyl-para-phenylenediamine (1) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis.
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Affiliation(s)
- Naoyuki Toriumi
- Department of Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Kazuya Yamashita
- Department of Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Nobuharu Iwasawa
- Department of Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo, 152-8551, Japan
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4
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Weinstain R, Slanina T, Kand D, Klán P. Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials. Chem Rev 2020; 120:13135-13272. [PMID: 33125209 PMCID: PMC7833475 DOI: 10.1021/acs.chemrev.0c00663] [Citation(s) in RCA: 271] [Impact Index Per Article: 67.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 02/08/2023]
Abstract
Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.
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Affiliation(s)
- Roy Weinstain
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Tomáš Slanina
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic
| | - Dnyaneshwar Kand
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Petr Klán
- Department
of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
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5
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Yang Y, Lu Z, Xu X. Phenacyl Xanthates: A Photoremovable Protecting Group for Alcohols under Visible Light. ASIAN J ORG CHEM 2019. [DOI: 10.1002/ajoc.201900576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Yong‐Qing Yang
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
| | - Zheng Lu
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
| | - Ximing Xu
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
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6
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Bisht R, Singh S, Krishnamoorthy K, Nithyanandhan J. Modulated photochemical reactivities of O-acetylated (3',5'-dimethoxyphenyl)heteroaryl acyloin derivatives under direct irradiation and photo-induced electron transfer conditions. Photochem Photobiol Sci 2018; 17:835-845. [PMID: 29799602 DOI: 10.1039/c8pp00082d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
3',5'-Dimethoxybenzoin esters are important photoremovable protecting groups which form 2-phenylbenzofuran derivatives upon photo-release. We utilized a similar concept to test a photochemical method of installing a benzofuran moiety to the conjugated backbone by subjecting O-acetylated (3',5'-dimethylphenyl)heteroaryl acyloin derivatives through direct photo irradiation and a photo-induced electron transfer reaction. These photochemical methods were explored for a variety of heteroaromatic substrates appended on the ketone part of the O-acetylated cross-acyloin derivatives. The furan, thiophene and bithiophene derivatives led to the expected cyclized (benzofuran capped) products but the derivatives with extended conjugation decomposed under direct irradiation. However, under irradiation in the presence of an electron donor such as triethylamine, the extended acyloin derivatives afforded both cyclized and deacetoxylated products. The semiconducting nature of the extended cyclized products was also explored and tested for solution-processed organic field effect transistors, providing a maximum hole mobility of 1.3 × 10-6 cm2 V-1 s-1.
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Affiliation(s)
- Rajesh Bisht
- Physical and Material Chemistry Division, CSIR-National Chemical Laboratory, CSIR-Network of Institutes for Solar Energy, Dr. Homi Bhaba Road, Pune, India 411008.
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7
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Madea D, Slanina T, Klán P. A 'photorelease, catch and photorelease' strategy for bioconjugation utilizing a p-hydroxyphenacyl group. Chem Commun (Camb) 2018; 52:12901-12904. [PMID: 27738680 DOI: 10.1039/c6cc07496k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A bioorthogonal 'catch and photorelease' strategy, which combines alkyne-azide cycloaddition between p-hydroxyphenacyl azide and alkyne derivatives to form a 1,2,3-triazole adduct and subsequent photochemical release of the triazole moiety via a photo-Favorskii rearrangement, is introduced. The first step can also involve photorelease of a strained alkyne and its Cu-free click reaction with azide.
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Affiliation(s)
- D Madea
- Department of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - T Slanina
- Department of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - P Klán
- Department of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
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8
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Speckmeier E, Zeitler K. Desyl and Phenacyl as Versatile, Photocatalytically Cleavable Protecting Groups: A Classic Approach in a Different (Visible) Light. ACS Catal 2017. [DOI: 10.1021/acscatal.7b02117] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Elisabeth Speckmeier
- Institut für Organische
Chemie, Universität Leipzig, Johannisallee 29, D-04103 Leipzig, Germany
| | - Kirsten Zeitler
- Institut für Organische
Chemie, Universität Leipzig, Johannisallee 29, D-04103 Leipzig, Germany
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9
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Bownik I, Šebej P, Literák J, Heger D, Šimek Z, Givens RS, Klán P. 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions. J Org Chem 2015; 80:9713-21. [DOI: 10.1021/acs.joc.5b01770] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
| | | | | | | | | | - Richard S. Givens
- Department
of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, 5010 Malott
Hall, Lawrence, Kansas 66045, United States
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10
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Faal T, Wong PT, Tang S, Coulter A, Chen Y, Tu CH, Baker JR, Choi SK, Inlay MA. 4-Hydroxytamoxifen probes for light-dependent spatiotemporal control of Cre-ER mediated reporter gene expression. MOLECULAR BIOSYSTEMS 2015; 11:783-90. [DOI: 10.1039/c4mb00581c] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Here, we synthesized and validated a photocaged hydroxytamoxifen molecule to achieve spatiotemporal control of gene expression with light.
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Affiliation(s)
- Tannaz Faal
- Sue and Bill Gross Stem Cell Research Center
- University of California Irvine
- Irvine
- USA
- Department of Molecular Biology and Biochemistry
| | - Pamela T. Wong
- Department of Internal Medicine
- Michigan Nanotechnology Institute for Medicine and Biological Sciences
- University of Michigan
- Ann Arbor
- USA
| | - Shengzhuang Tang
- Department of Internal Medicine
- Michigan Nanotechnology Institute for Medicine and Biological Sciences
- University of Michigan
- Ann Arbor
- USA
| | - Alexa Coulter
- Department of Internal Medicine
- Michigan Nanotechnology Institute for Medicine and Biological Sciences
- University of Michigan
- Ann Arbor
- USA
| | - Yumay Chen
- Sue and Bill Gross Stem Cell Research Center
- University of California Irvine
- Irvine
- USA
- Department of Medicine
| | - Christina H. Tu
- Sue and Bill Gross Stem Cell Research Center
- University of California Irvine
- Irvine
- USA
| | - James R. Baker
- Department of Internal Medicine
- Michigan Nanotechnology Institute for Medicine and Biological Sciences
- University of Michigan
- Ann Arbor
- USA
| | - Seok Ki Choi
- Department of Internal Medicine
- Michigan Nanotechnology Institute for Medicine and Biological Sciences
- University of Michigan
- Ann Arbor
- USA
| | - Matthew A. Inlay
- Sue and Bill Gross Stem Cell Research Center
- University of California Irvine
- Irvine
- USA
- Department of Molecular Biology and Biochemistry
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11
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Klán P, Šolomek T, Bochet CG, Blanc A, Givens R, Rubina M, Popik V, Kostikov A, Wirz J. Photoremovable protecting groups in chemistry and biology: reaction mechanisms and efficacy. Chem Rev 2013; 113:119-91. [PMID: 23256727 PMCID: PMC3557858 DOI: 10.1021/cr300177k] [Citation(s) in RCA: 1248] [Impact Index Per Article: 113.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Indexed: 02/06/2023]
Affiliation(s)
- Petr Klán
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
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12
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Edson JB, Spencer LP, Boncella JM. Photorelease of Primary Aliphatic and Aromatic Amines by Visible-Light-Induced Electron Transfer. Org Lett 2011; 13:6156-9. [DOI: 10.1021/ol202456d] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph B. Edson
- Materials, Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Liam P. Spencer
- Materials, Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - James M. Boncella
- Materials, Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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13
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An HY, Kwok WM, Ma C, Guan X, Kan JTW, Toy PH, Phillips DL. Photophysics and Photodeprotection Reactions of p-Methoxyphenacyl Phototriggers: An Ultrafast and Nanosecond Time-Resolved Spectroscopic and Density Functional Theory Study. J Org Chem 2010; 75:5837-51. [DOI: 10.1021/jo100848b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hui-Ying An
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Wai Ming Kwok
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong S. A. R., P. R. China
| | - Chensheng Ma
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Xiangguo Guan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Jovi Tze Wai Kan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Patrick H. Toy
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
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14
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Borak JB, Falvey DE. Ketocoumarin dyes as electron mediators for visible light induced carboxylate photorelease. Photochem Photobiol Sci 2010; 9:854-60. [DOI: 10.1039/c0pp00072h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Borak JB, Falvey DE. A new photolabile protecting group for release of carboxylic acids by visible-light-induced direct and mediated electron transfer. J Org Chem 2009; 74:3894-9. [PMID: 19361187 DOI: 10.1021/jo900182x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new aqueous-compatible photoinduced electron transfer based photolabile protecting group has been developed for the release of carboxylic acids. The reduction potential of this group is more positive than previous systems, thereby allowing the use of sensitizers with modest oxidation potentials. Release of several carboxylic acids has been demonstrated using tris(bipyridyl)ruthenium(II) as both a direct sensitizer and a mediator for electron transfer between a good donor and the protecting group.
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Affiliation(s)
- J Brian Borak
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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16
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Kulikov A, Arumugam S, Popik VV. Photolabile Protection of Alcohols, Phenols, and Carboxylic Acids with 3-Hydroxy-2-Naphthalenemethanol. J Org Chem 2008; 73:7611-5. [DOI: 10.1021/jo801302m] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Anton Kulikov
- Department of Chemistry, University of Georgia, Athens, Georgia 30602
| | | | - Vladimir V. Popik
- Department of Chemistry, University of Georgia, Athens, Georgia 30602
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17
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1-Oxoindan-2-yl and 1,3-dioxoindan-2-yl esters as photoremovable protecting groups. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2007.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Borak JB, López-Sola S, Falvey DE. Photorelease of Carboxylic Acids Mediated by Visible-Light-Absorbing Gold-Nanoparticles. Org Lett 2007; 10:457-60. [DOI: 10.1021/ol702813w] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Brian Borak
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Susana López-Sola
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Daniel E. Falvey
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
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19
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Kostikov AP, Popik VV. 2,5-Dihydroxybenzyl and (1,4-Dihydroxy-2-naphthyl)methyl, Novel Reductively Armed Photocages for the Hydroxyl Moiety. J Org Chem 2007; 72:9190-4. [DOI: 10.1021/jo701426j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Vladimir V. Popik
- Department of Chemistry, University of Georgia, Athens, Georgia 30602
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20
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Use of a scientific microwave apparatus for rapid optimization of reaction conditions in a monomode function and then substrate screening in a multimode function. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.04.074] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Kammari L, Plístil L, Wirz J, Klán P. 2,5-Dimethylphenacyl carbamate: a photoremovable protecting group for amines and amino acids. Photochem Photobiol Sci 2007; 6:50-6. [PMID: 17200736 DOI: 10.1039/b612233g] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2,5-Dimethylphenacyl (DMP) carbamates (1a-c) released the corresponding free amines or amino acids in high chemical yields, albeit with quantum yields Phi of only 0.04-0.09, upon irradiation in either aprotic or protic solvents. The photoreaction proceeded principally from the triplet excited state via the E-photoenol. The lifetimes of the triplet enol and the E- and Z-enols in the ground state were determined by laser flash photolysis. The primary photoinitiated transformation liberated a carbamic acid derivative, which subsequently decarboxylated to the amino group-containing compound. Exhaustive irradiation of a DMP-protected aniline (1a) in acetonitrile did not provide aniline in quantitative chemical yields, because it was involved in reductive cleavage of the starting material as an electron donor, thereby decreasing the overall deprotection yield (86%). Phenylalanine methyl ester, liberated from 1c, was, however, obtained in excellent chemical yield (97%). It was also found that the carbamates, while thermally stable, released amines with higher quantum yields in acidic methanol solutions. The DMP chromophore is proposed as an excellent photoremovable protecting group for amino acids and, under specific conditions, for amines in organic synthesis and biochemistry.
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Affiliation(s)
- Laxminarayana Kammari
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37, Brno, Czech Republic
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22
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Wöll D, Smirnova J, Pfleiderer W, Steiner UE. Highly Efficient Photolabile Protecting Groups with Intramolecular Energy Transfer. Angew Chem Int Ed Engl 2006; 45:2975-8. [PMID: 16555354 DOI: 10.1002/anie.200504091] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Dominik Wöll
- Fachbereich Chemie, Universität Konstanz, Universitätstrasse 10, 78464 Konstanz, Germany
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23
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Wöll D, Smirnova J, Pfleiderer W, Steiner UE. Hocheffiziente photolabile Schutzgruppen mit intramolekularem Energietransfer. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200504091] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Literák J, Dostálová A, Klán P. Chain Mechanism in the Photocleavage of Phenacyl and Pyridacyl Esters in the Presence of Hydrogen Donors. J Org Chem 2005; 71:713-23. [PMID: 16408984 DOI: 10.1021/jo0521551] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] Excited phenacyl and 3-pyridacyl esters of benzoic acid react with an excess of aliphatic alcohols in a chain reaction process involving hydrogen transfer from the ketyl radical intermediates, leading to benzoic acid in addition to acetophenone and 3-acetylpyridine, respectively, as the byproducts. While the maximum quantum yields reached 4 in both cases, the 2- or 4-pyridacyl ester photoreduction proceeded with the efficiency below 100% under the same conditions. The investigation indicates that a radical coupling between ketyl radicals, both formed from the excited ester by hydrogen abstraction from an alcohol, is accompanied by the elimination of benzoic acid from the ester ketyl radical itself. A partitioning between two reactions was found to be remarkably sensitive to the chromophore nature, such as a position of the nitrogen atom in the pyridacyl moiety. The magnitude of a radical chain process is dependent on the efficiency of consecutive steps that produce free radicals capable of a subsequent ester reduction. The driving force of a possible electron transfer from the ketyl radicals to the ester has been excluded on the basis of cyclic voltametry measurements. The observed quantum yields of photoreduction were found to be diminished by formation of relatively long-lived light absorbing transients, coproducts obtained apparently by secondary photochemical reactions. Additionally, it is shown that basic additives such as pyridine can further increase the efficiency of the photoreduction by a factor of 4. A radical nature of the reduction mechanism was supported by finding a large kinetic chain length of an analogous reaction initiated by free radicals generated thermally yet again when phenacyl or 3-pyridacyl benzoate was used. Both phenacyl and pyridacyl chromophores are pronounced to be valuable as the photoremovable protecting groups when high quantum and chemical yields of carboxylic acid elimination are important, but higher concentrations of the hydrogen atom donors are not destructive for a reaction system or are experimentally impractical.
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Affiliation(s)
- Jaromír Literák
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ - 611 37 Brno, Czech Republic
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25
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Sundararajan C, Falvey DE. Photolytic Release of Carboxylic Acids Using Linked Donor−Acceptor Molecules: Direct versus Mediated Photoinduced Electron Transfer to N-Alkyl-4-picolinium Esters. Org Lett 2005; 7:2631-4. [PMID: 15957908 DOI: 10.1021/ol050744n] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Efficient photorelease (Phi = 0.7) of carboxylic acids is achieved with a covalently linked mediator (benzophenone) protecting group (N-alkyl-4-picolinium ester) molecule. The mechanism involves initial photoreduction of the mediator, followed by rapid electron transfer to the protecting group.
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Affiliation(s)
- Chitra Sundararajan
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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26
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Sundararajan C, Falvey DE. Photorelease of Carboxylic Acids, Amino Acids, and Phosphates from N-Alkylpicolinium Esters Using Photosensitization by High Wavelength Laser Dyes. J Am Chem Soc 2005; 127:8000-1. [PMID: 15926809 DOI: 10.1021/ja050760f] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Visible light (>450 nm) is used to efficiently cleave carboxylic acids, amino acids, and phosphates from their N-methyl picolinium esters. Photolysis using pyrromethene dyes PM 546 and PM 597 and also coumarin 6 as photosensitizers effects release of carboxylic acids, N-protected amino acids, and phosphates in quantitative yields. The effective rate of photorelease by the dyes, Phiepsilon, was found to be as high as 4500 M-1 cm-1. The photorelease proceeds through photoinduced electron transfer from the dye sensitizers to the N-methyl picolinium group. Fluorescence quenching and laser flash photolysis experiments support the photoinduced electron-transfer mechanism.
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Affiliation(s)
- Chitra Sundararajan
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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Ma C, Kwok WM, Chan WS, Zuo P, Wai Kan JT, Toy PH, Phillips DL. Ultrafast Time-Resolved Study of Photophysical Processes Involved in the Photodeprotection ofp-Hydroxyphenacyl Caged Phototrigger Compounds. J Am Chem Soc 2005; 127:1463-72. [PMID: 15686379 DOI: 10.1021/ja0458524] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A combined femtosecond Kerr gated time-resolved fluorescence (fs-KTRF) and picosecond Kerr gated time-resolved resonance Raman (ps-KTR(3)) study is reported for two p-hydroxyphenacyl (pHP) caged phototriggers, HPDP and HPA, in neat acetonitrile and water/acetonitrile (1:1 by volume) solvents. Fs-KTRF spectroscopy was employed to characterize the spectral properties and dynamics of the singlet excited states, and the ps-KTR(3) was used to monitor the formation and subsequent reaction of triplet state. These results provide important evidence for elucidation of the initial steps for the pHP deprotection mechanism. An improved fs-KTRF setup was developed to extend its detectable spectral range down to the 270 nm UV region while still covering the visible region up to 600 nm. This combined with the advantage of KTRF in directly monitoring the temporal evolution of the overall fluorescence profile enables the first time-resolved observation of dual fluorescence for pHP phototriggers upon 267 nm excitation. The two emitting components were assigned to originate from the (1)pipi (S(3)) and (1)npi (S(1)) states, respectively. This was based on the lifetime, the spectral location, and how these varied with the type of solvent. By correlating the dynamics of the singlet decay with the triplet formation, a direct (1)npi --> (3)pipi ISC mechanism was found for these compounds with the ISC rate estimated to be approximately 5 x 10(11) s(-)(1) in both solvent systems. These photophysical processes were found to be little affected by the kind of leaving group indicating the common local pHP chromophore is largely responsible for the fluorescence and relevant deactivation processes. The triplet lifetime was found to be approximately 420 and 2130 ps for HPDP and HPA, respectively, in the mixed solvent compared to 150 and 137 ns, respectively, in neat MeCN. The solvent and leaving group dependent quenching of the triplet is believed to be associated with the pHP deprotection photochemistry and indicates that the triplet is the reactive precursor for pHP photorelease reactions for the compounds examined in this study.
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Affiliation(s)
- Chensheng Ma
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China
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Papageorgiou G, Barth A, Corrie JET. Flash photolytic release of alcohols from photolabile carbamates or carbonates is rate-limited by decarboxylation of the photoproduct. Photochem Photobiol Sci 2005; 4:216-20. [PMID: 15696240 DOI: 10.1039/b417153e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Flash photolysis of a 7-nitroindolinyl carbamate derivative in neutral aqueous solution rapidly generated a monoalkyl carbonate salt. The rate constant for subsequent decarboxylation of this salt [mono(2-phosphoryloxyethyl) carbonate], determined by rapid scan IR difference spectroscopy, was 0.4 s(-1) at pH 7.0, 20 degrees C. This rate reflects release of the product alcohol upon photolysis of the parent compound. In general, alcohols protected as photolabile carbamate (or carbonate) derivatives will therefore be released too slowly for studies of the kinetics of millisecond time scale biological processes.
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Affiliation(s)
- George Papageorgiou
- National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK NW7 1AA
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30
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Literak J, Wirz J, Klán P. 2,5-Dimethylphenacyl carbonates: A photoremovable protecting group for alcohols and phenols. Photochem Photobiol Sci 2005; 4:43-6. [PMID: 15616690 DOI: 10.1039/b408851d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthesis and photochemistry of a photochemically removable protecting group for alcohols and phenols, based on the 2,5-dimethylphenacyl (DMP) chromophore, is described. DMP carbonates release the corresponding hydroxy group containing molecules in high isolated yields (>70%), with quantum yields Phi= 0.1-0.2 in methanol and Phi= 0.36-0.51 in cyclohexane. The reactions proceed predominantly by the triplet pathway via E-photoenols, the lifetimes of which of approximately 2 s or 3 ms in cyclohexane or methanol, respectively, were determined by laser flash photolysis.
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Affiliation(s)
- Jaromír Literak
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic
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Ma C, Zuo P, Kwok WM, Chan WS, Kan JTW, Toy PH, Phillips DL. Time-Resolved Resonance Raman Study of the Triplet States of p-Hydroxyacetophenone and the p-Hydroxyphenacyl Diethyl Phosphate Phototrigger Compound. J Org Chem 2004; 69:6641-57. [PMID: 15387586 DOI: 10.1021/jo049331a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pico- and nanosecond time-resolved resonance Raman (TR3) spectroscopy have been utilized to study the dynamics and structure of p-hydroxyacetophenone (HA) and the p-hydroxyphenacyl-caged phototrigger compound p-hydroxyphenacyl diethyl phosphate (HPDP) in acetonitrile solution. Transient intermediates were detected and attributed to the triplet states of HA and HPDP. Nanosecond-TR3 measurements were done for two isotopically substituted HA molecules to help better assign the triplet state carbonyl C=O stretching and the ring related vibrational modes. The dynamics of formation and the spectral characteristics for the triplet states were found to be similar for the HA and HPDP. The temporal evolution at very early picosecond time scale indicates there is rapid intersystem crossing (ISC) conversion and subsequent relaxation of the excess energy of the initially produced energetic triplet state. B3LYP/6-311G** density functional theory (DFT) calculations were done to determine the structures and vibrational frequencies for both the triplet and ground states of HA and HPDP. The calculated spectra reproduce the experimental spectra and the observed isotopic shifts reasonably well and were used to make tentative assignments to all the experimentally observed features. The triplet states were found to have extensive conjugated pipi* nature with a single-bond-like carbonyl CO bond. We briefly compare the triplet structure and formation dynamics of HA and HPDP as well as the conformational changes upon going from the ground state to the triplet state. We discuss our present results in relation to the initial pathway for the p-hydroxyphenacyl photodeprotection process. We also compare and discuss the properties of the HA pipi* triplet state relative to the published results of other aromatic carbonyl compounds.
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Affiliation(s)
- Chensheng Ma
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China
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Klán P, Pelliccioli AP, Pospísil T, Wirz J. 2,5-dimethylphenacyl esters: a photoremovable protecting group for phosphates and sulfonic acids. Photochem Photobiol Sci 2002; 1:920-3. [PMID: 12659533 DOI: 10.1039/b208171g] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2,5-Dimethylphenacyl phosphoric and sulfonic esters release the corresponding acids upon irradiation in nearly quantitative isolated yields, with quantum yields phi = 0.71 and 0.68 in methanol, 0.09 and 0.19 in benzene. In methanol solution the reactions proceed predominantly via the (Z)-photoenol, the lifetimes of which (20 and 25 micros) were determined by laser flash photolysis. The chromophore is proposed as an excellent photoremovable protecting group for use in organic synthesis and biochemistry.
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Affiliation(s)
- Petr Klán
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic.
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Pelliccioli AP, Wirz J. Photoremovable protecting groups: reaction mechanisms and applications. Photochem Photobiol Sci 2002; 1:441-58. [PMID: 12659154 DOI: 10.1039/b200777k] [Citation(s) in RCA: 511] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photolabile protecting groups enable biochemists to control the release of bioactive compounds in living tissue. 'Caged compounds' (photoactivatable bioagents) have become an important tool to study the events that follow chemical signalling in, e.g., cell biology and the neurosciences. The possibilities are by no means exhausted. Progress will depend on the development of photoremovable protecting groups that satisfy the diverse requirements of new applications--a challenging task for photochemists.
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Affiliation(s)
- Anna Paola Pelliccioli
- Institut für Physikalische Chemie, Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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Zabadal M, Pelliccioli AP, Klán P, Wirz J. 2,5-Dimethylphenacyl Esters: A Photoremovable Protecting Group for Carboxylic Acids. J Phys Chem A 2001. [DOI: 10.1021/jp010220e] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Miroslav Zabadal
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic, and Institut für Physikalische Chemie der Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Anna Paola Pelliccioli
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic, and Institut für Physikalische Chemie der Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Petr Klán
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic, and Institut für Physikalische Chemie der Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Jakob Wirz
- Department of Organic Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic, and Institut für Physikalische Chemie der Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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Lee K, Falvey DE. Photochemically Removable Protecting Groups Based on Covalently Linked Electron Donor−Acceptor Systems. J Am Chem Soc 2000. [DOI: 10.1021/ja9939441] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kwangjoo Lee
- Contribution from the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Daniel E. Falvey
- Contribution from the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
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2,5-Dimethylphenacyl as a new photoreleasable protecting group for carboxylic acids. Org Lett 2000; 2:1569-71. [PMID: 10841481 DOI: 10.1021/ol005789x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 2,5-dimethylphenacyl chromophore, a new photoremovable protecting group for carboxylic acids, is proposed. Direct photolysis of various 2,5-dimethylphenacyl esters in benzene or methanol at 254-366 nm leads to the formation of the corresponding carboxylic acids in almost quantitative isolated yields. The photodeprotection is based on efficient intramolecular hydrogen abstraction without the necessity of introducing a photosensitizer.
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