1
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Miller L, Bauer F, Breit B. A Tandem Hydroformylation-Organocatalyzed Friedel-Crafts Reaction for the Synthesis of Diindolylmethanes. Chemistry 2024; 30:e202400188. [PMID: 38411034 DOI: 10.1002/chem.202400188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 02/28/2024]
Abstract
Herein, we present an efficient and atom-economic tandem hydroformylation organocatalyzed Friedel-Crafts reaction sequence for the synthesis of diindolylmethanes. Classic syntheses have relied on (Lewis) acid activation of aldehydes, which are often not commercially available and rather sensitive in handling. In contrast, the combination of rhodium-catalyzed hydroformylation and subsequent organocatalytic activation of the in-situ formed aldehydes allows the use of readily available and stable alkenes with various functional groups while avoiding acidic conditions to expand the range of available diindolylmethanes. A broad scope of diindolylmethanes was prepared in yields up to 85 % demonstrates the utility of the presented method.
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Affiliation(s)
- Lukas Miller
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
| | - Felix Bauer
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
| | - Bernhard Breit
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany
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2
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Kolagkis PX, Galathri EM, Kokotos CG. Green and sustainable approaches for the Friedel-Crafts reaction between aldehydes and indoles. Beilstein J Org Chem 2024; 20:379-426. [PMID: 38410780 PMCID: PMC10896228 DOI: 10.3762/bjoc.20.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/07/2024] [Indexed: 02/28/2024] Open
Abstract
The synthesis of indoles and their derivatives, more specifically bis(indolyl)methanes (BIMs), has been an area of great interest in organic chemistry, since these compounds exhibit a range of interesting biological and pharmacological properties. BIMs are naturally found in cruciferous vegetables and have been shown to be effective antifungal, antibacterial, anti-inflammatory, and even anticancer agents. Traditionally, the synthesis of BIMs has been achieved upon the acidic condensation of an aldehyde with indole, utilizing a variety of protic or Lewis acids. However, due to the increased environmental awareness of our society, the focus has shifted towards the development of greener synthetic technologies, like photocatalysis, organocatalysis, the use of nanocatalysts, microwave irradiation, ball milling, continuous flow, and many more. Thus, in this review, we summarize the medicinal properties of BIMs and the developed BIM synthetic protocols, utilizing the reaction between aldehydes with indoles, while focusing on the more environmentally friendly methods developed over the years.
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Affiliation(s)
- Periklis X Kolagkis
- Laboratory of Organic Chemistry, Department of Organic Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece
| | - Eirini M Galathri
- Laboratory of Organic Chemistry, Department of Organic Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece
| | - Christoforos G Kokotos
- Laboratory of Organic Chemistry, Department of Organic Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece
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3
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Jiaping J, Woldegiorgis AG, Lin X. Chiral spirocyclic phosphoric acid-catalyzed enantioselective synthesis of heterotriarylmethanes bearing an amino acid moiety. RSC Adv 2023; 13:18964-18973. [PMID: 37362600 PMCID: PMC10285616 DOI: 10.1039/d3ra03480a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 06/17/2023] [Indexed: 06/28/2023] Open
Abstract
We present herein an enantioselective protocol for the chiral phosphoric acid-catalyzed addition of 3-arylisoxazol-5-amines to highly reactive 3-methide-3H-pyrroles to provide a diverse range of heterotriarylmethanes bearing an amino acid moiety in good yields (up to 97%) and high enantioselectivities (up to 93% ee) under mild conditions. The chiral spirocyclic phosphoric acid is crucial in converting the initial 1H-pyrrol-3-yl carbinols into reactive 3-methide-3H-pyrroles and obtaining the good enantiocontrol, thereby facilitating the desired enantioselective transformation.
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Affiliation(s)
- Jin Jiaping
- Center of Chemistry for Frontier Technologies, Department of Chemistry, Zhejiang University Hangzhou 310058 China
| | | | - Xufeng Lin
- Center of Chemistry for Frontier Technologies, Department of Chemistry, Zhejiang University Hangzhou 310058 China
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4
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Galathri EM, Di Terlizzi L, Fagnoni M, Protti S, Kokotos CG. Friedel-Crafts arylation of aldehydes with indoles utilizing arylazo sulfones as the photoacid generator. Org Biomol Chem 2023; 21:365-369. [PMID: 36512428 DOI: 10.1039/d2ob02214a] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A versatile, inexpensive and sustainable protocol for the preparation of valuable bis-indolyl methanes via visible light-mediated, metal-free Friedel-Crafts arylation has been developed. The procedure, that exploits the peculiar behavior of arylazo sulfones as non-ionic photoacid generators (PAGs), was applied to the conversion of a variety of aliphatic and aromatic aldehydes into diarylmethanes in good to highly satisfactory yields, employing a low-catalyst loading (0.5 mol%) and irradiation at 456 nm.
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Affiliation(s)
- Eirini M Galathri
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15771, Greece.
| | - Lorenzo Di Terlizzi
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, Pavia 27100, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, Pavia 27100, Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, Pavia 27100, Italy
| | - Christoforos G Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15771, Greece.
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5
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Pan X, Han T, Long J, Xie B, Du Y, Zhao Y, Zheng X, Xue J. Excited state proton transfer of triplet state p-nitrophenylphenol to amine and alcohol: a spectroscopic and kinetic study. Phys Chem Chem Phys 2022; 24:18427-18434. [PMID: 35881619 DOI: 10.1039/d2cp02503e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Hydroxyaromatic compounds (ArOHs) have a wide range of applications in catalytic synthesis and biological processes due to their increased acidity upon photo-excitation. The proton transfer of ArOHs via the excited singlet state has been extensively studied. However, there has still been a debate on the unique type of ArOH that can undergo an ultrafast intersystem crossing. The nitro group in p-nitrophenylphenol (NO2-Bp-OH) enhances the spin-orbit coupling between excited singlet states and the triplet manifold, enabling ultrafast intersystem crossing and the formation of the long-lived lowest excited triplet state (T1) with a high yield. In this work, we used time-resolved transient absorption to investigate the excited state proton transfer of NO2-Bp-OH in its T1 state to t-butylamine, methanol, and ethanol. The T1 state of the deprotonated form NO2-Bp-O- was first observed and identified in the case of t-butylamine. Kinetic analysis demonstrates that the formation of the hydrogen-bonded complex with methanol and ethanol as proton acceptors involves their trimers. The alcohol oligomer size required in the excited state proton transfer process is dependent on the excited acidity of photoacid.
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Affiliation(s)
- Xinghang Pan
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Ting Han
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Jing Long
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Binbin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou, 310018, China
| | - Yong Du
- Centre for THz Research, China Jiliang University, Hangzhou, 310018, China
| | - Yanying Zhao
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China. .,Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Xuming Zheng
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Jiadan Xue
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou, 310018, China. .,Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, China
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6
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Saway J, Pierre AF, Badillo JJ. Photoacid-catalyzed acetalization of carbonyls with alcohols. Org Biomol Chem 2022; 20:6188-6192. [PMID: 35876112 DOI: 10.1039/d2ob00435f] [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
In this report, we demonstrate that visible light photoactivation of 6-bromo-2-naphthol facilitates the photoacid-catalyzed acetalization of carbonyls with alcohols. We also demonstrate that 2-naphthol when coupled to a photosensitizer provides acetals from electron-deficient aldehydes. In addition, the S1 excited state pKa for 6-bromo-2-naphthol in water was determined and shown to have increased excited-state acidity relative to 2-naphthol.
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Affiliation(s)
- Jason Saway
- Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ, 07079, USA.
| | - Abigail F Pierre
- Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ, 07079, USA.
| | - Joseph J Badillo
- Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ, 07079, USA.
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7
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Di Terlizzi L, Martinelli A, Merli D, Protti S, Fagnoni M. Arylazo Sulfones as Nonionic Visible-Light Photoacid Generators. J Org Chem 2022; 88:6313-6321. [PMID: 35866712 DOI: 10.1021/acs.joc.2c01248] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The selective visible-light-driven generation of a weak acid (sulfinic acid, in nitrogen-purged solutions) or a strong acid (sulfonic acid, in oxygen-purged solutions) by using shelf-stable arylazo sulfones was developed. These sulfones were then used for the green, smooth, and efficient photochemical catalytic protection of several (substituted) alcohols (and phenols) as tetrahydropyranyl ethers or acetals.
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Affiliation(s)
- Lorenzo Di Terlizzi
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Angelo Martinelli
- Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Daniele Merli
- Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
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8
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Chigumbu P, Fu J, Takia IRT, Wang Y, Han X. Friedel-Crafts Benzylation of Unprotected Anilines with Indole-3-
carbinols to Access Trifluoro-methyl(indolyl)phenylmethanes. LETT ORG CHEM 2022. [DOI: 10.2174/1570178618666210225114226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
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An unprecedented protocol for the efficient and highly chemoselective alkylation of unprotected anilines with deactivated CF3-indole-3-carbinols promoted by In(OTf)3 has been developed. A series of diversified trifluoromethylated (indolyl)phenylmethanes were produced featuring the C-alkylation in moderate to high chemical yields and with high regioselectivities.
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Affiliation(s)
- Paidamoyo Chigumbu
- Provincial Key Laboratory for Chemical & Biological Processing, Technology of Farm Products, School of Biological
and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, China, 310023
| | - Junfeng Fu
- Provincial Key Laboratory for Chemical & Biological Processing, Technology of Farm Products, School of Biological
and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, China, 310023
| | - Ingrid Rakielle Tsapy Takia
- Provincial Key Laboratory for Chemical & Biological Processing, Technology of Farm Products, School of Biological
and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, China, 310023
| | - Yongjiang Wang
- Provincial Key Laboratory for Chemical & Biological Processing, Technology of Farm Products, School of Biological
and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, China, 310023
| | - Xiaoyu Han
- Provincial Key Laboratory for Chemical & Biological Processing, Technology of Farm Products, School of Biological
and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, China, 310023
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9
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Yang B, Dong K, Li XS, Wu LZ, Liu Q. Photoacid-Enabled Synthesis of Indanes via Formal [3 + 2] Cycloaddition of Benzyl Alcohols with Olefins. Org Lett 2022; 24:2040-2044. [PMID: 35243864 DOI: 10.1021/acs.orglett.2c00566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An environmentally friendly and highly diastereoselective method for synthesizing indanes has been developed via a metastable-state photoacid system containing catalytic protonated merocyanine (MEH). Under visible-light irradiation, MEH yields a metastable spiro structure and liberated protons, which facilitates the formation of carbocations from benzyl alcohols, thus delivering diverse molecules in the presence of various nucleophiles. Mainly, a variety of indanes could be easily obtained from benzyl alcohols and olefins, and water is the only byproduct.
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Affiliation(s)
- Biao Yang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Kui Dong
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Xiang-Sheng Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
| | - Li-Zhu Wu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, the Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Qiang Liu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China
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10
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Roy VJ, Sen PP, Roy SR. Exploring Eosin Y as a bimodular catalyst: organophotoacid mediated Minisci-type acylation of N-heteroarenes. Chem Commun (Camb) 2022; 58:1776-1779. [PMID: 35037922 DOI: 10.1039/d1cc06483e] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we report Eosin Y as a bimodular catalyst for Minisci-type acylation reactions. The formation of organic exciplexes between photoexcited Eosin Y and N-heteroarenes was found to be a stabilizing factor for photoacid catalysis under optimized conditions. Spectroscopic investigations such as steady state fluorescence quenching and dynamic lifetime quenching experiments were employed to better understand the role of Eosin Y as both a photoredox catalyst and a photoacid. Feedstock aldehydes were employed as acyl radical precursors for engaging in C-C bond formation reactions with a variety of nitrogen containing heterocycles.
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Affiliation(s)
- Vishal Jyoti Roy
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
| | - Partha Pratim Sen
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
| | - Sudipta Raha Roy
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
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11
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Zhao G, Li J, Wang T. Visible-light-induced photoacid catalysis: application in glycosylation with O-glycosyl trichloroacetimidates. Chem Commun (Camb) 2021; 57:12659-12662. [PMID: 34768281 DOI: 10.1039/d1cc04887b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The development of visible-light-induced photoacid catalyzed glycosylation is reported. The eosin Y and PhSSPh catalyst system is applied to realize glycosylation with different glycosyl donors upon light irradiation. The reaction shows a broad substrate scope, including both glycosyl donors and acceptors, and highlights the mild nature of the reaction conditions.
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Affiliation(s)
- Gaoyuan Zhao
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
| | - Juncheng Li
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
| | - Ting Wang
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
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12
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Wati FA, Santoso M, Moussa Z, Fatmawati S, Fadlan A, Judeh ZMA. Chemistry of trisindolines: natural occurrence, synthesis and bioactivity. RSC Adv 2021; 11:25381-25421. [PMID: 35478918 PMCID: PMC9037102 DOI: 10.1039/d1ra03091d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/11/2021] [Indexed: 01/18/2023] Open
Abstract
Heterocyclic nitrogen compounds are privileged structures with many applications in the pharmaceutical and nutraceutical industries since they possess wide bioactivities. Trisindolines are heterocyclic nitrogen compounds consisting of an isatin core bearing two indole moieties. Trisindolines have been synthesized by reacting isatins with indoles using various routes and the yield greatly depends on the catalyst used, reaction conditions, and the substituents on both the isatin and indole moieties. Amongst the synthetic routes, acid-catalyzed condensation reaction between isatins and indoles are the most useful due to high yield, wide scope and short reaction times. Trisindolines are biologically active compounds and show anticancer, antimicrobial, antitubercular, antifungal, anticonvulsant, spermicidal, and antioxidant activities, among others. Trisindolines have not previously been reviewed. Therefore, this review aims to provide a comprehensive account of trisindolines including their natural occurrence, routes of synthesis, and biological activities. It aims to inspire the discovery of lead trisindoline drug candidates for further development. This in-depth review of trisindolines covers their natural occurrence in addition to several routes of synthesis and catalysts used. The biological activities of trisindolines have been discussed with a special emphasis on the structure–activity relationship.![]()
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Affiliation(s)
- First Ambar Wati
- Department of Chemistry, Institut Teknologi Sepuluh Nopember Kampus ITS, Sukolilo Surabaya 60111 Indonesia
| | - Mardi Santoso
- Department of Chemistry, Institut Teknologi Sepuluh Nopember Kampus ITS, Sukolilo Surabaya 60111 Indonesia
| | - Ziad Moussa
- Department of Chemistry, College of Science, United Arab Emirates University P. O. Box 15551 Al Ain United Arab Emirates
| | - Sri Fatmawati
- Department of Chemistry, Institut Teknologi Sepuluh Nopember Kampus ITS, Sukolilo Surabaya 60111 Indonesia
| | - Arif Fadlan
- Department of Chemistry, Institut Teknologi Sepuluh Nopember Kampus ITS, Sukolilo Surabaya 60111 Indonesia
| | - Zaher M A Judeh
- School of Chemical and Biomedical Engineering, Nanyang Technological University 62 Nanyang Drive, N1.2-B1-14 Singapore 637459 Singapore
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13
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Badillo JJ, Saway J, Salem ZM. Recent Advances in Photoacid Catalysis for Organic Synthesis. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/s-0040-1705952] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractPhotoacids are molecules that become more acidic upon the absorption of light. This short review highlights recent advances in the use of photoacids as catalysts for organic synthesis. Photoacid-catalyzed transformations discussed herein include: Protonation, glycosylation, acetalization, and arylation reactions.1 Introduction2 Protonation: Excited-State Proton Transfer (ESPT)3 Glycosylation4 Acetalization5 Friedel–Crafts Arylation6 Additional C–C and C–S Bond-Forming Reactions7 Conclusion
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14
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Dutta A, Patra SK, Khatua S, Nongkhlaw R. Visible-light-mediated synthesis of 3,4,5-trisubstituted furan-2-one derivatives via a bifunctional organo photocatalyst. NEW J CHEM 2021. [DOI: 10.1039/d1nj03238k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This protocol demonstrates sustainable synthesis of furan-2-one derivatives using organo photocatalyst under visible-light irradiation and DFT studies of the compound.
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Affiliation(s)
- Arup Dutta
- Centre for Advanced Studies in Chemistry, Department of Chemistry, North-Eastern Hill University, Shillong-793022, India
| | - Sumit Kumar Patra
- Centre for Advanced Studies in Chemistry, Department of Chemistry, North-Eastern Hill University, Shillong-793022, India
| | - Snehadrinarayan Khatua
- Centre for Advanced Studies in Chemistry, Department of Chemistry, North-Eastern Hill University, Shillong-793022, India
| | - Rishanlang Nongkhlaw
- Centre for Advanced Studies in Chemistry, Department of Chemistry, North-Eastern Hill University, Shillong-793022, India
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15
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Empel C, Jana S, Pei C, Nguyen TV, Koenigs RM. Photochemical O–H Functionalization of Aryldiazoacetates with Phenols via Proton Transfer. Org Lett 2020; 22:7225-7229. [DOI: 10.1021/acs.orglett.0c02564] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Claire Empel
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
| | - Sripati Jana
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Chao Pei
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Thanh Vinh Nguyen
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
| | - Rene M. Koenigs
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
- School of Chemistry, University of New South Waley, Sydney 2052, Australia
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16
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Arakawa Y, Mihara T, Fujii H, Minagawa K, Imada Y. An uncommon use of irradiated flavins: Brønsted acid catalysis. Chem Commun (Camb) 2020; 56:5661-5664. [PMID: 32315001 DOI: 10.1039/d0cc01960g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present that thioacetalization of aldehydes can be induced by blue light irradiation in the presence of a catalytic amount of riboflavin tetraacetate (RFTA) under aerobic conditions. Several control experiments have suggested that the reaction is more likely to be catalyzed by acidic species generated in situ upon light irradiation. We have proposed that single electron transfer from a thiol (RSH) to the excited state of RFTA can take place to give a one-electron oxidized thiol (RSH+˙) and the one-electron reduced RFTA (RFTA-˙), which can be trapped by molecular oxygen to be stabilized as Brønsted acids including the protonated RFTA-˙ (RFTAH˙). Finally, we have demonstrated that such acidic species can be prepared in advance as a solution and used as Brønsted acid catalysts for not only thioacetalization but also Mannich-type reactions.
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Affiliation(s)
- Yukihiro Arakawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Tomohiro Mihara
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Hiroki Fujii
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Keiji Minagawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan. and Institute of Liberal Arts and Sciences, Tokushima University, Minamijosanjima, Tokushima 770-8502, Japan
| | - Yasushi Imada
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
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17
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Photoinduzierte Protonentransferreaktionen für milde O‐H‐Funktionalisierungsreaktionen unreaktiver Alkohole. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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18
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Jana S, Yang Z, Li F, Empel C, Ho J, Koenigs RM. Photoinduced Proton-Transfer Reactions for Mild O-H Functionalization of Unreactive Alcohols. Angew Chem Int Ed Engl 2020; 59:5562-5566. [PMID: 31880397 PMCID: PMC7154649 DOI: 10.1002/anie.201915161] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/26/2019] [Indexed: 12/16/2022]
Abstract
Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. Mechanistic studies indicate there is a preorganization of hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen-bonding complex. Only after photoexcitation does this complex undergo a protonation-substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O-H functionalization reactions (54 examples, up to 98 % yield).
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Affiliation(s)
- Sripati Jana
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Zhen Yang
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Fang Li
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Claire Empel
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Junming Ho
- School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Rene M Koenigs
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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