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Tripathi J, Gupta H, Sharma A. Photoacid-Catalyzed Esterification of Carboxylic Acids Using Eosin Y. Org Lett 2025; 27:1018-1023. [PMID: 39836875 DOI: 10.1021/acs.orglett.4c04639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2025]
Abstract
A photoacid-catalyzed method for esterification is proposed wherein eosin Y is introduced as a photoacid and photoredox catalyst that can be activated with visible light and catalyze the esterification of carboxylic acids. The strategy presented here revealed that proton-coupled electron transfer (PCET) between eosin Y and carboxylic acid might facilitate the formation of a transient ketyl radical. This ketyl radical would subsequently undergo a single electron transfer and then couple with alkyl alcohols, yielding carboxylic esters in good to excellent yields.
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Affiliation(s)
- Jaya Tripathi
- Department of Chemistry, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India
| | - Harshita Gupta
- Department of Chemistry, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India
| | - Anuj Sharma
- Department of Chemistry, Indian Institute of Technology, Roorkee, Uttarakhand 247667, India
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Sülzner N, Jung G, Nuernberger P. A dual experimental-theoretical perspective on ESPT photoacids and their challenges ahead. Chem Sci 2025; 16:1560-1596. [PMID: 39759939 PMCID: PMC11697080 DOI: 10.1039/d4sc07148d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2024] [Accepted: 11/22/2024] [Indexed: 01/07/2025] Open
Abstract
Photoacids undergo an increase in acidity upon electronic excitation, enabling excited-state proton transfer (ESPT) reactions. A multitude of compounds that allow ESPT has been identified and integrated in numerous applications, as is outlined by reviewing the rich history of photoacid research reaching back more than 90 years. In particular, achievements together with ambitions and challenges are highlighted from a combined experimental and theoretical perspective. Besides explicating the spectral signatures, transient ion-pair species, and electronic states involved in an ESPT, special emphasis is put on the diversity of methods used for studying photoacids as well as on the effects of the environment on the ESPT, illustrated in detail for 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) and the naphthols as examples of prototypical photoacids. The development of exceptionally acidic super-photoacids and magic photoacids is subsequently discussed, which opens the way to applications even in aprotic solvents and provides additional insight into the mechanisms underlying ESPT. In the overview of highlights from theory, a comprehensive picture of the scope of studies on HPTS is presented, along with the general conceptualization of the electronic structure of photoacids and approaches for the quantification of excited-state acidity. We conclude with a juxtaposition of established applications of photoacids together with potential open questions and prospective research directions.
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Affiliation(s)
- Niklas Sülzner
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum 44780 Bochum Germany +49 234 32 24523
| | - Gregor Jung
- Biophysikalische Chemie, Universität des Saarlandes 66123 Saarbrücken Germany +49 681 302 71320
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg 93040 Regensburg Germany +49 941 943 4487
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Borah B, Sharma S, Chavada SK, Swain S, Chowhan LR. Photochemical domino reaction driven C-H/S-H functionalization of bioactive molecules to access xanthene scaffolds. Org Biomol Chem 2024; 22:8453-8458. [PMID: 39331024 DOI: 10.1039/d4ob01117a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
A visible-light-induced C(sp2)-H functionalization of indoles by using Schreiner's thiourea as the organocatalyst has been reported. With the aid of a three-component domino reaction between 2-hydroxybenzaldehydes, cyclic-1,3-diketones, and a variety of indoles, the corresponding densely functionalized xanthene scaffolds were isolated in good to excellent yields. Apart from these, a broad range of other bioactive natural products including kojic acid, lawsone, and 4-hydroxycoumarin were also investigated instead of indoles for the present work. All the molecules participated in the photochemical reaction smoothly and provided the desired xanthenes in synthetically valuable yields. Therefore, the present energy-efficient catalytic strategy was also very successful in executing challenging carbon-sulfur bond formation reactions, demonstrating the synthetic potentiality of the work. Notably, this air-stable, transition metal-free approach with broad functional group tolerability provides an alternative to conventional methods.
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Affiliation(s)
- Biplob Borah
- School of Applied Material Sciences, Central University of Gujarat, Sector-30, Gandhinagar-382030, India.
- Royal School of Applied & Pure Sciences, The Assam Royal Global University, Guwahati-781035, Assam, India
| | - Samrita Sharma
- School of Applied Material Sciences, Central University of Gujarat, Sector-30, Gandhinagar-382030, India.
| | - Snehalkumar K Chavada
- School of Applied Material Sciences, Central University of Gujarat, Sector-30, Gandhinagar-382030, India.
| | - Sidharth Swain
- School of Applied Material Sciences, Central University of Gujarat, Sector-30, Gandhinagar-382030, India.
| | - L Raju Chowhan
- School of Applied Material Sciences, Central University of Gujarat, Sector-30, Gandhinagar-382030, India.
- School of Physical Sciences, Jawaharlal Nehru University, New Mehrauli Road, New Delhi-110067, India.
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Borah B, Chowhan LR. Photoredox-Catalyzed Cross-Coupling of In Situ Generated Quinoxalinones with Indoles for the Synthesis of Tertiary Alcohols. J Org Chem 2024; 89:14740-14754. [PMID: 39374938 DOI: 10.1021/acs.joc.4c01322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/09/2024]
Abstract
A visible light-driven photoredox-catalyzed direct C(sp2)-H functionalization of N-H free indoles with quinoxalinones generated in situ from 2,2-dihydroxy-1H-indene-1,3(2H)-dione and phenylene-1,2-diamines has been reported with the aid of Na2-Eosin Y as the photocatalyst and the Hünig base as the sacrificial electron and proton donor. The reaction provides easy access to a variety of quaternary-centered C-3 selective indole-substituted tertiary alcohols in good yields. Mechanistic studies demonstrated the realization of photoredox-catalyzed in situ quinoxalinone formation and their proton-coupled single electron reduction to the corresponding ketyl radicals followed by cross-coupling with indoles. The potential applications of the synthesized tertiary alcohols in photoacid-catalyzed carbon-carbon and carbon-sulfur bond-forming reactions feature the key findings of the present work.
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Affiliation(s)
- Biplob Borah
- School of Applied Material Sciences, Centre for Applied Chemistry, Central University of Gujarat, Sector-30, Gandhinagar 382030, India
- Department of Chemistry, Royal School of Applied & Pure Sciences, The Assam Royal Global University, Guwahati, Assam 781035, India
| | - L Raju Chowhan
- School of Applied Material Sciences, Centre for Applied Chemistry, Central University of Gujarat, Sector-30, Gandhinagar 382030, India
- School of Physical Sciences, Jawaharlal Nehru University, New Mehrauli Road, New Delhi 110067, India
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Hu XT, Cheng QY, Chen YP, Li K, Yan CX, Li D, Shao LD. Hydroxymethylation hydroxylation of 1,3-diarylpropene through a catalytic diastereoselective Prins reaction: cyclization logic and access to brazilin core. NATURAL PRODUCTS AND BIOPROSPECTING 2024; 14:29. [PMID: 38740677 DOI: 10.1007/s13659-024-00450-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 04/21/2024] [Indexed: 05/16/2024]
Abstract
A catalytic diastereoselective Prins reaction for hydroxymethylation and hydroxylation of 1,3-diarylpropene was successfully utilized to prepare various 1,3-dioxanes 7 in 14-88% yields. Take advantage of the synthetic intermediate 7h, the key B/C rings in brazilin core could be constructed by the sequential of Friedel-Crafts/Ullmann-Ma rather than Ullmann-Ma/Friedel-Crafts reactions.
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Affiliation(s)
- Xin-Ting Hu
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Qing-Yan Cheng
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Yan-Ping Chen
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Kun Li
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Cai-Xian Yan
- Yunnan Precious Metals Laboratory, Kunming Institute of Precious Metals, Kunming, 650106, China
| | - Dashan Li
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Li-Dong Shao
- Yunnan Key Laboratory of Southern Medicinal Utilization, School of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China.
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Shekhar C, Satyanarayana G. Acid-Mediated Domino Cyclization of ortho-Formyl Cinnamate Esters: Synthesis of Substituted Indene/Indane Esters and Indeno[ a]indenones. J Org Chem 2024; 89:5069-5090. [PMID: 38497282 DOI: 10.1021/acs.joc.4c00301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
A Bro̷nsted acid-driven protocol to access substituted monoarylindene esters, biarylindane esters, and indeno[a]indenones from simple ortho-formylcinnamate esters and external arenes has been revealed. Remarkably, this single-pot process enabled the construction of two, three, and four new C-C bonds in building monoarylindene esters, biarylindane esters, and indeno[a]indenones, respectively, under metal-free and mild reaction parameters via triggering the inactive cinnamate ester moiety. In addition, the present strategy is investigated with widespread substrate scope.
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Affiliation(s)
- Chander Shekhar
- Indian Institute of Technology Hyderabad, Sangareddy, Telangana 502 284, India
| | - Gedu Satyanarayana
- Indian Institute of Technology Hyderabad, Sangareddy, Telangana 502 284, India
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Zhang F, Wei Z, Wu W, Liu N, Li X, Zou L, Wang K, Xu J, Fan B. Photocatalyst-free visible light driven synthesis of gem-dihaloenones from alkynes, tetrahalomethanes and water. Org Biomol Chem 2023; 21:719-723. [PMID: 36416357 DOI: 10.1039/d2ob01983c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Photocatalytic reactions, in particular, processes without photosensitisers, have attracted increased attention due to their green aspect and high economic value and are considered valuable tools in organic synthesis. A new practical photocatalytic system was investigated in this study, and it can efficiently produce gem-dihaloenones by combining terminal alkynes with tetrahalomethanes (BrCCl3 and CBr4) and water without a photocatalyst, and the yield can reach up to 87%. The catalytic system is straightforward, the raw materials are inexpensive and easy to obtain, and the operation is simple.
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Affiliation(s)
- Fuqing Zhang
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Zixiang Wei
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Wei Wu
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Na Liu
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China. .,Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming, Yunnan, 650504, China
| | - Xinhan Li
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Luqian Zou
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Kaiming Wang
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China.
| | - Jianbin Xu
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China. .,Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming, Yunnan, 650504, China
| | - Baomin Fan
- School of chemistry and Environment, Yunnan Minzu University, Kunmin 650504, China. .,Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming, Yunnan, 650504, China
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