1
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Wang T, Li Z, Gao H, Hu J, Chen HY, Xu JJ. Ultrafast C-C and C-N bond formation reactions in water microdroplets facilitated by the spontaneous generation of carbocations. Chem Sci 2023; 14:11515-11520. [PMID: 37886101 PMCID: PMC10599473 DOI: 10.1039/d3sc03870j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/24/2023] [Indexed: 10/28/2023] Open
Abstract
Carbocations are important electrophilic intermediates in organic chemistry, but their formation typically requires harsh conditions such as extremely low pH, elevated temperature, strong oxidants and/or expensive noble-metal catalysts. Herein, we report the spontaneous generation of highly reactive carbocations in water microdroplets by simply spraying a diarylmethanol aqueous solution. The formation of transient carbocations as well as their ultrafast in-droplet transformations through carbocation-involved C-C and C-N bond formation reactions are directly characterized by mass spectrometry. The intriguing formation and stabilization of carbocations are attributed to the super acidity of the positively charged water microdroplets as well as the high electric fields at the water-air interfaces. Without the utilization of external acids as catalysts, we believe that these microdroplet reactions would pose a new and sustainable way for the construction of aryl-substituted compounds.
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Affiliation(s)
- Ting Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210023 P. R. China
| | - Zheng Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210023 P. R. China
| | - Hang Gao
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210023 P. R. China
| | - Jun Hu
- School of Life Sciences and Health Engineering, Jiangnan University Wuxi 214122 China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210023 P. R. China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210023 P. R. China
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2
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Hazra G, Masarwa A. Synthesis and Functionalization of Thiophosphonium Salts: A Divergent Approach to Access Thioether, Thioester, and Dithioester Derivatives. Org Lett 2023; 25:6396-6400. [PMID: 37610079 PMCID: PMC10476193 DOI: 10.1021/acs.orglett.3c02422] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Indexed: 08/24/2023]
Abstract
Herein, we report a straightforward practical method for efficiently obtaining a diverse range of thiophosphonium salts. This method involves the direct coupling of commercially available thiols and aldehydes with Ph3P and TfOH. The setup is simple and carried out in a metal-free manner. The synthetic utility of these salts is demonstrated through various examples of C-P bond functionalizations, enabling the synthesis of thioether, deuterated thioether, thioester, and dithioester derivatives. These products, which serve as valuable building blocks, are obtained in high yields.
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Affiliation(s)
- Gurupada Hazra
- Institute of Chemistry, The
Center for Nanoscience and Nanotechnology, and Casali Center for Applied
Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ahmad Masarwa
- Institute of Chemistry, The
Center for Nanoscience and Nanotechnology, and Casali Center for Applied
Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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3
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Mei S, Ou Q, Tang X, Xu JF, Zhang X. Stabilization of Carbocation Intermediate by Cucurbit[7]uril Enables High Photolysis Efficiency. Org Lett 2023; 25:5291-5296. [PMID: 37428144 DOI: 10.1021/acs.orglett.3c01854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
A cucurbit[7]uril-based host-guest strategy is employed to enhance the efficiency of photolysis reactions that release caged molecules from photoremovable protecting groups. The photolysis of benzyl acetate follows a heterolytic bond cleavage mechanism, thereby leading to the formation of a contact ion pair as the key reactive intermediate. The Gibbs free energy of the contact ion pair is lowered by 3.06 kcal/mol through the stabilization of cucurbit[7]uril, as revealed by DFT calculations, which results in a 40-fold increase in the quantum yield of the photolysis reaction. This methodology is also applicable to the chloride leaving group and the diphenyl photoremovable protecting group. We anticipate that this research presents a novel strategy to improve reactions involving active cationics, thereby enriching the field of supramolecular catalysis.
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Affiliation(s)
- Shan Mei
- Key Laboratory of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Qi Ou
- AI for Science Institute, Beijing 100080, China
- DP Technology, Beijing 100080, China
| | - Xingchen Tang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jiang-Fei Xu
- Key Laboratory of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xi Zhang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
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4
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Yu ZL, Chen JW, Chen YL, Zheng RJ, Ma M, Chen JP, Shen ZL, Chu XQ. DMSO-Promoted Difluoroalkylation of Organophosphonium Salts with Difluoroenol Silyl Ethers. Org Lett 2022; 24:5557-5561. [PMID: 35867631 DOI: 10.1021/acs.orglett.2c02088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An efficient method for the synthesis of β,β-di(hetero)aryl-α,α-difluorinated ketones using readily available organophosphonium salts and difluoroenol silyl ethers has been developed. This mild reaction features a good functional group tolerance, a scaled-up synthesis, and synthetic simplicity. By taking advantage of DMSO as a less-toxic promoter and solvent for the difluoroalkylation and C-P bond functionalization, the use of transition-metal catalysts and sensitive additives could be avoided.
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Affiliation(s)
- Zi-Lun Yu
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Jia-Wei Chen
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Yu-Lan Chen
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Ren-Jun Zheng
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Mengtao Ma
- Department of Chemistry and Materials Science, College of Science, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jian-Ping Chen
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Zhi-Liang Shen
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Xue-Qiang Chu
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
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5
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Tan F, Zheng P, Liu Q, Chen XY. Charge Transfer Complex Enabled Photoreduction of Wittig Phosphonium Salts. Org Chem Front 2022. [DOI: 10.1039/d2qo01079h] [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
A photoinduced charge transfer complex strategy enabled (alkoxycarbonyl)methylation reaction of alkenes with phosphonium salts has been reported. This strategy provides a convenient strategy to functionalize indoles, 1,1-diphenylethylenes, enamides and N-phenyl...
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6
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Micheletti G, Mayer RJ, Cino S, Boga C, Mazzanti A, Ofial AR, Mayr H. Quantification of the Lewis Basicities and Nucleophilicities of 1,3,5‐Tris(dialkylamino)benzenes. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Gabriele Micheletti
- Department of Industrial Chemistry ‘Toso Montanari' Alma Mater Studiorum – Università di Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Robert J. Mayer
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 München Germany
| | - Silvia Cino
- Department of Industrial Chemistry ‘Toso Montanari' Alma Mater Studiorum – Università di Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Carla Boga
- Department of Industrial Chemistry ‘Toso Montanari' Alma Mater Studiorum – Università di Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Andrea Mazzanti
- Department of Industrial Chemistry ‘Toso Montanari' Alma Mater Studiorum – Università di Bologna Viale Risorgimento 4 40136 Bologna Italy
| | - Armin R. Ofial
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 München Germany
| | - Herbert Mayr
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 München Germany
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7
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Babu KN, Massarwe F, Shioukhi I, Masarwa A. Sequential Selective C-H and C(sp 3 )- + P Bond Functionalizations: An Entry to Bioactive Arylated Scaffolds. Angew Chem Int Ed Engl 2021; 60:26199-26209. [PMID: 34618394 DOI: 10.1002/anie.202111164] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Indexed: 12/14/2022]
Abstract
Organophosphonium salts containing C(sp3 )-+ P bonds are among the most utilized reagents in organic synthesis for constructing C-C double bonds. However, their use as C-selective electrophilic groups is rare. Here, we explore an efficient and general transition-metal-free method for sequential chemo- and regioselective C-H and C(sp3 )-+ P bond functionalizations. In the present study, C-H alkylation resulting in the synthesis of benzhydryl triarylphosphonium salts was achieved by one-pot, four-component cross-coupling reactions of simple and commercially available starting materials. The utility of the resulting phosphonium salt building blocks was demonstrated by the chemoselective post-functionalization of benzylic C(sp3 )-+ PPh3 groups to achieve aminations, thiolations, and arylations. In this way, benzhydrylamines, benzhydrylthioethers, and triarylmethanes, structural motifs that are present in many pharmaceuticals and agrochemicals, are readily accessed. These include the synthesis of two anticancer agents from simple materials in only two to three steps. Additionally, a protocol for late-stage functionalization of bioactive drugs has been developed using benzhydrylphosphonium salts. This new approach should provide novel transformations for application in both academic and pharmaceutical research.
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Affiliation(s)
- K Naresh Babu
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Fedaa Massarwe
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Israa Shioukhi
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Ahmad Masarwa
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
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8
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Babu KN, Massarwe F, Shioukhi I, Masarwa A. Sequential Selective C−H and C(sp
3
)−
+
P Bond Functionalizations: An Entry to Bioactive Arylated Scaffolds. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- K. Naresh Babu
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Fedaa Massarwe
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Israa Shioukhi
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 9190401 Israel
| | - Ahmad Masarwa
- Institute of Chemistry The Hebrew University of Jerusalem Jerusalem 9190401 Israel
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9
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Liu Q, Lu Y, Sheng H, Zhang C, Su X, Wang Z, Chen X. Visible‐Light‐Induced Selective Photolysis of Phosphonium Iodide Salts for Monofluoromethylations. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Qiang Liu
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Yu Lu
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - He Sheng
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Chao‐Shen Zhang
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Xiao‐Di Su
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Zhi‐Xiang Wang
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Xiang‐Yu Chen
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
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10
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Liu Q, Lu Y, Sheng H, Zhang CS, Su XD, Wang ZX, Chen XY. Visible-Light-Induced Selective Photolysis of Phosphonium Iodide Salts for Monofluoromethylations. Angew Chem Int Ed Engl 2021; 60:25477-25484. [PMID: 34490742 DOI: 10.1002/anie.202111006] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Indexed: 11/09/2022]
Abstract
The sigma (σ)-hole effect has emerged as a promising tool to construct novel architectures endowed with new properties. A simple yet effective strategy for the generation of monofluoromethyl radicals is a continuing challenge within the synthetic community. Fluoromethylphosphonium salts are easily available, air- and thermally stable, as well as simple-to-handle. Herein, we report the ability of the σ-hole effect to facilitate the visible-light-triggered photolysis of phosphonium iodide salts, a charge-transfer complex, selectively giving fluoromethyl radicals. The usefulness and versatility of this new protocol are demonstrated through the mono-, di-, and trifluoromethylation of a variety of alkenes.
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Affiliation(s)
- Qiang Liu
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu Lu
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - He Sheng
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chao-Shen Zhang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao-Di Su
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi-Xiang Wang
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiang-Yu Chen
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
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11
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Maji B, Duan XH, Jüstel PM, Byrne PA, Ofial AR, Mayr H. Nucleophilicities and Nucleofugalities of Thio- and Selenoethers. Chemistry 2021; 27:11367-11376. [PMID: 34002899 PMCID: PMC8456842 DOI: 10.1002/chem.202100977] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Indexed: 12/19/2022]
Abstract
Rate constants for the reactions of dialkyl chalcogenides with laser flash photolytically generated benzhydrylium ions have been measured photometrically to integrate them into the comprehensive benzhydrylium‐based nucleophilicity scale. Combining these rate constants with the previously reported equilibrium constants for the same reactions provided the corresponding Marcus intrinsic barriers and made it possible to quantify the leaving group abilities (nucleofugalities) of dialkyl sulfides and dimethyl selenide. Due to the low intrinsic barriers, dialkyl chalcogenides are fairly strong nucleophiles (comparable to pyridine and N‐methylimidazole) as well as good nucleofuges; this makes them useful group‐transfer reagents.
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Affiliation(s)
- Biplab Maji
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Xin-Hua Duan
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,Department of Chemistry, School of Chemistry, Xi'an Key Laboratory of Sustainable Energy Material Chemistry, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an, 710049, P. R. China
| | - Patrick M Jüstel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
| | - Peter A Byrne
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,School of Chemistry, University College Cork, College Road, Cork, Ireland
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
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12
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Karbalaei Khani S, Geissler B, Engelage E, Nuernberger P, Hättig C. Tracing absorption and emission characteristics of halogen-bonded ion pairs involving halogenated imidazolium species. Phys Chem Chem Phys 2021; 23:7480-7494. [PMID: 33876108 DOI: 10.1039/d1cp00009h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We investigate how the absorption and fluorescence of halogenated imidazolium compounds in acetonitrile solution is influenced by the presence of counterions and the ability to act as halogen-bond donors. Experimental measurements and quantum chemical calculations with correlated wavefunction methods are applied to study three monodentate halogen-bond complexes of iodo-imidazolium, iodo-benzimidazolium and bromo-benzimidazolium cations with triflate counterions, and a bidentate complex of bis(iodo-benzimidazolium) dications with chloride as counterion. The three monodentate complexes with triflate counterions relax after photoexcitation to minima on the S1 potential energy surface where the C-I bond and the IO halogen bond are partially broken. For the bidentate complex with the smaller chloride counterion the halogen-bond interaction stays intact in the S1 minimum that is reached by relaxation from the Franck-Condon point. In a complementing experimental approach, stationary absorption and emission as well as transient fluorescence spectra are recorded for iodo- and bromo-benzimidazolium in acetonitrile. Variation of the counterion, substitution of the iodine by bromine, hydrogen, or methyl, and the comparison to theory allows the identification of spectroscopic signatures and photoinduced dynamics associated with ion-pairing.
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13
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Knorr J, Sokkar P, Costa P, Sander W, Sanchez-Garcia E, Nuernberger P. How Protic Solvents Determine the Reaction Mechanisms of Diphenylcarbene in Solution. J Org Chem 2019; 84:11450-11457. [PMID: 31343881 DOI: 10.1021/acs.joc.9b01228] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We investigate the effects of small admixtures of protic solvent molecules, such as water and alcohols, on the ultrafast dynamics of diphenylcarbene in acetonitrile at room temperature. Broadband transient absorption measurements and quantum mechanics/molecular mechanics molecular dynamics simulations allow elucidating the dominant reaction mechanism of an intermediate hydrogen-bonded complex between singlet diphenylcarbene and a protic solvent molecule, thus competing with intersystem crossing. Analysis of the data indicates that complex formation is a diffusion-controlled process with orientational requirements. The reaction path involving a benzhydryl cation is less likely in neat bulkier alcohols, as it requires the interaction of the carbene with a protic solvent molecule being part of a hydrogen-bonded network. The simulations indicate a further reaction path toward O-H insertion and two side reactions depending on the involved protic solvent species. Thus, we established that not only the number but also the chemical nature of the protic solvent molecule determine which reaction path is pursued.
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Affiliation(s)
| | - Pandian Sokkar
- Computational Biochemistry, Center of Medical Biotechnology , University of Duisburg-Essen , 45117 Essen , Germany
| | | | | | - Elsa Sanchez-Garcia
- Computational Biochemistry, Center of Medical Biotechnology , University of Duisburg-Essen , 45117 Essen , Germany
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14
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Fedorov OV, Scherbinina SI, Levin VV, Dilman AD. Light-Mediated Dual Phosphine-/Copper-Catalyzed Atom Transfer Radical Addition Reaction. J Org Chem 2019; 84:11068-11079. [DOI: 10.1021/acs.joc.9b01649] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oleg V. Fedorov
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
| | - Sofya I. Scherbinina
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
- Higher Chemical College, D. Mendeleev University of Chemical Technology of Russia, Miusskaya sq. 9, 125047 Moscow, Russian Federation
| | - Vitalij V. Levin
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
| | - Alexander D. Dilman
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
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15
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Panferova LI, Levin VV, Struchkova MI, Dilman AD. Light-mediated copper-catalyzed phosphorus/halogen exchange in 1,1-difluoroalkylphosphonium salts. Chem Commun (Camb) 2019; 55:1314-1317. [DOI: 10.1039/c8cc09115c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Phosphorus/halogen exchange in fluorinated phosphonium salts is promoted by light and catalyzed by copper(i) halides.
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Affiliation(s)
- Liubov I. Panferova
- N. D. Zelinsky Institute of Organic Chemistry
- 119991 Moscow
- Russian Federation
| | - Vitalij V. Levin
- N. D. Zelinsky Institute of Organic Chemistry
- 119991 Moscow
- Russian Federation
| | | | - Alexander D. Dilman
- N. D. Zelinsky Institute of Organic Chemistry
- 119991 Moscow
- Russian Federation
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16
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Hu P, Berning K, Lam YW, Ng IHM, Yeung CC, Lam MHW. Development of a Visible Light Triggerable Traceless Staudinger Ligation Reagent. J Org Chem 2018; 83:12998-13010. [DOI: 10.1021/acs.joc.8b01370] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peng Hu
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Karsten Berning
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Yun-Wah Lam
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Isabel Hei-Ma Ng
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
| | - Chi-Chung Yeung
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China
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17
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Mayer RJ, Hampel N, Mayer P, Ofial AR, Mayr H. Synthesis, Structure, and Properties of Amino-Substituted Benzhydrylium Ions - A Link between Ordinary Carbocations and Neutral Electrophiles. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800835] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Robert J. Mayer
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstraße 5-13 81377 München Germany
| | - Nathalie Hampel
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstraße 5-13 81377 München Germany
| | - Peter Mayer
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstraße 5-13 81377 München Germany
| | - Armin R. Ofial
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstraße 5-13 81377 München Germany
| | - Herbert Mayr
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstraße 5-13 81377 München Germany
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18
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Kumara MN, Nakahara T, Kobayashi S, Fujio M, Mishima M. Nucleophilicities of Alcohols and Water in Acetonitrile Based on Reactivities of Benzhydrylium Ions. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2018. [DOI: 10.1246/bcsj.20170360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Manikyanahally N. Kumara
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Tesshu Nakahara
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Shinjiro Kobayashi
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Mizue Fujio
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Masaaki Mishima
- Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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19
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Abstract
The dynamics of chemical reactions in liquid solutions are now amenable to direct study using ultrafast laser spectroscopy techniques and advances in computer simulation methods. The surrounding solvent affects the chemical reaction dynamics in numerous ways, which include: (i) formation of complexes between reactants and solvent molecules; (ii) modifications to transition state energies and structures relative to the reactants and products; (iii) coupling between the motions of the reacting molecules and the solvent modes, and exchange of energy; (iv) solvent caging of reactants and products; and (v) structural changes to the solvation shells in response to the changing chemical identity of the solutes, on timescales which may be slower than the reactive events. This article reviews progress in the study of bimolecular chemical reaction dynamics in solution, concentrating on reactions which occur on ground electronic states. It illustrates this progress with reference to recent experimental and computational studies, and considers how the various ways in which a solvent affects the chemical reaction dynamics can be unravelled. Implications are considered for research in fields such as mechanistic synthetic chemistry.
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Affiliation(s)
- Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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20
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Radhakrishnan S, Mieres-Perez J, Gudipati MS, Sander W. Photoinduced Reversible Electron Transfer Between the Benzhydryl Radical and Benzhydryl Cation in Amorphous Water–Ice. J Phys Chem A 2017; 121:6405-6412. [DOI: 10.1021/acs.jpca.7b05466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Soumya Radhakrishnan
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Joel Mieres-Perez
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Murthy S. Gudipati
- Science
Division, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Wolfram Sander
- Lehrstuhl
für Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
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21
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Masui Y, Hattori T, Onaka M. Reversible Generation of Labile Secondary Carbocations from Alcohols in the Nanospace of H-Mordenite and Their Long-Lasting Preservation at Ambient Temperature. J Am Chem Soc 2017; 139:8612-8620. [PMID: 28565906 DOI: 10.1021/jacs.7b03336] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Secondary carbocations are rarely observed spectrometrically for prolonged durations at ambient temperatures because of their instability. In this study, when 4,4'-difluorobenzhydrol (1) was mixed with H-mordenite (H-Mor), the 4,4'-difluorodiphenylmethyl cation (2) was generated as the main product, identified by UV-vis and 13C-MAS NMR spectroscopies, and was preserved for over 1 week at ambient temperature. Surprisingly, the polymerization and disproportionation of 1 barely proceeded within the micropores of H-Mor. However, these side reactions prevailed in TfOH and formation of 2 was not observed. Preservation of other secondary carbocations from benzhydrol, 4,4'-dichlorobenzhydrol, and 9-fluorenol was also realized in H-Mor. It was confirmed that the generation of 2 from 1 was controlled by thermodynamic equilibrium rather than kinetic regulations. The equilibrium between 2 and 1 was accompanied by reversible chromism, which could be easily controlled by altering the moisture content in H-Mor. Moreover, novel insights into specific acid catalysis in zeolites densely populated with acid sites on the inner surface of micropores are described herein.
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Affiliation(s)
- Yoichi Masui
- Graduate School of Arts and Sciences, The University of Tokyo , 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Taiki Hattori
- Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Makoto Onaka
- Graduate School of Arts and Sciences, The University of Tokyo , 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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22
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Shi S, Croutxé-Barghorn C, Allonas X. Photoinitiating systems for cationic photopolymerization: Ongoing push toward long wavelengths and low light intensities. Prog Polym Sci 2017. [DOI: 10.1016/j.progpolymsci.2016.09.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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23
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Vidil T, Tournilhac F, Musso S, Robisson A, Leibler L. Control of reactions and network structures of epoxy thermosets. Prog Polym Sci 2016. [DOI: 10.1016/j.progpolymsci.2016.06.003] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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24
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Knorr J, Sokkar P, Schott S, Costa P, Thiel W, Sander W, Sanchez-Garcia E, Nuernberger P. Competitive solvent-molecule interactions govern primary processes of diphenylcarbene in solvent mixtures. Nat Commun 2016; 7:12968. [PMID: 27708264 PMCID: PMC5059701 DOI: 10.1038/ncomms12968] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 08/22/2016] [Indexed: 12/02/2022] Open
Abstract
Photochemical reactions in solution often proceed via competing reaction pathways comprising intermediates that capture a solvent molecule. A disclosure of the underlying reaction mechanisms is challenging due to the rapid nature of these processes and the intricate identification of how many solvent molecules are involved. Here combining broadband femtosecond transient absorption and quantum mechanics/molecular mechanics simulations, we show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour. The hydrogen bonding dynamics determine which reaction channels are accessible in binary solvent mixtures at room temperature. In-depth analysis of the amount of nascent intermediates corroborates the importance of a hydrogen-bonded complex with a protic solvent molecule, in striking analogy to complexes found at cryogenic temperatures. Our results show that adjacent solvent molecules take the role of key abettors rather than bystanders for the fate of the reactive intermediate. Photochemistry in solution often involves coexisting reaction channels that may comprise intermediates capturing a solvent molecule. Here, the authors show for one of the most reactive species, diphenylcarbene, that the decision-maker is not the nearest solvent molecule but its neighbour.
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Affiliation(s)
- Johannes Knorr
- Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Pandian Sokkar
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Sebastian Schott
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Paolo Costa
- Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Wolfram Sander
- Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Elsa Sanchez-Garcia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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25
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Hu P, Feng T, Yeung CC, Koo CK, Lau KC, Lam MHW. A Photo-Triggered Traceless Staudinger-Bertozzi Ligation Reaction. Chemistry 2016; 22:11537-42. [DOI: 10.1002/chem.201601807] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Peng Hu
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
| | - Tianshi Feng
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
- Advanced Laboratory for Environmental Research & Technology; USTC-CityU Suzhou China
- CAS Key Laboratory of Soft Matter Chemistry; Department of Polymer Science and Engineering; University of Science and Technology of China, Hefei; Anhui 230026 China
| | - Chi-Chung Yeung
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
| | - Chi-Kin Koo
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
| | - Kai-Chung Lau
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
| | - Michael H. W. Lam
- Department of Chemistry and Biology; City University of Hong Kong; 83 Tat Chee Avenue Hong Kong SAR China
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Thallmair S, Roos MK, de Vivie-Riedle R. Molecular features in complex environment: Cooperative team players during excited state bond cleavage. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2016; 3:043205. [PMID: 26958588 PMCID: PMC4752547 DOI: 10.1063/1.4941600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 12/22/2015] [Indexed: 06/05/2023]
Abstract
Photoinduced bond cleavage is often employed for the generation of highly reactive carbocations in solution and to study their reactivity. Diphenylmethyl derivatives are prominent precursors in polar and moderately polar solvents like acetonitrile or dichloromethane. Depending on the leaving group, the photoinduced bond cleavage occurs on a femtosecond to picosecond time scale and typically leads to two distinguishable products, the desired diphenylmethyl cations (Ph2CH(+)) and as competing by-product the diphenylmethyl radicals ([Formula: see text]). Conical intersections are the chief suspects for such ultrafast branching processes. We show for two typical examples, the neutral diphenylmethylchloride (Ph2CH-Cl) and the charged diphenylmethyltriphenylphosphonium ions ([Formula: see text]) that the role of the conical intersections depends not only on the molecular features but also on the interplay with the environment. It turns out to differ significantly for both precursors. Our analysis is based on quantum chemical and quantum dynamical calculations. For comparison, we use ultrafast transient absorption measurements. In case of Ph2CH-Cl, we can directly connect the observed signals to two early three-state and two-state conical intersections, both close to the Franck-Condon region. In case of the [Formula: see text], dynamic solvent effects are needed to activate a two-state conical intersection at larger distances along the reaction coordinate.
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Affiliation(s)
| | - Matthias K Roos
- Department Chemie, Ludwig-Maximilians-Universität München , D-81377 München, Germany
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27
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Thallmair S, Roos MK, de Vivie-Riedle R. Design of specially adapted reactive coordinates to economically compute potential and kinetic energy operators including geometry relaxation. J Chem Phys 2016; 144:234104. [DOI: 10.1063/1.4953667] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- Sebastian Thallmair
- Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität München, D-80538 München, Germany
| | - Matthias K. Roos
- Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
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28
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Byrne PA, Kobayashi S, Breugst M, Laub H, Mayr H. Quantification of the nucleophilic reactivity of nicotine. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Peter A. Byrne
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 81377 München Germany
| | - Shinjiro Kobayashi
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 81377 München Germany
| | - Martin Breugst
- Department für Chemie; Universität zu Köln; Greinstraße 4 50939 Köln Germany
| | - Hans Laub
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 81377 München Germany
| | - Herbert Mayr
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstr. 5-13 81377 München Germany
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29
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Thallmair S, Zauleck JPP, de Vivie-Riedle R. Quantum Dynamics in an Explicit Solvent Environment: A Photochemical Bond Cleavage Treated with a Combined QD/MD Approach. J Chem Theory Comput 2015; 11:1987-95. [DOI: 10.1021/acs.jctc.5b00046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sebastian Thallmair
- Department
Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
- Lehrstuhl
für BioMolekulare Optik, Ludwig-Maximilians-Universität München, D-80538 München, Germany
| | - Julius P. P. Zauleck
- Department
Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
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30
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Mayr H, Ammer J, Baidya M, Maji B, Nigst TA, Ofial AR, Singer T. Scales of Lewis basicities toward C-centered Lewis acids (carbocations). J Am Chem Soc 2015; 137:2580-99. [PMID: 25555037 DOI: 10.1021/ja511639b] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Equilibria for the reactions of benzhydryl cations (Ar2CH(+)) with phosphines, tert-amines, pyridines, and related Lewis bases were determined photometrically in CH2Cl2 and CH3CN solution at 20 °C. The measured equilibrium constants can be expressed by the sum of two parameters, defined as the Lewis Acidity (LA) of the benzhydrylium ions and the Lewis basicity (LB) of the phosphines, pyridines, etc. Least-squares minimization of log K = LA + LB with the definition LA = 0 for (4-MeOC6H4)2CH(+) gave a Lewis acidity scale for 18 benzhydrylium ions covering 18 orders of magnitude in CH2Cl2 as well as Lewis basicities (with respect to C-centered Lewis acids) for 56 bases. The Lewis acidities correlated linearly with the quantum chemically calculated (B3LYP/6-311++G(3df,2pd)//B3LYP/6-31G(d,p) level) methyl anion affinities of the corresponding benzhydrylium ions, which can be used as reference compounds for characterizing a wide variety of Lewis bases. The equilibrium measurements were complemented by isothermal titration calorimetry studies. Rates of SN1 solvolyses of benzhydryl chlorides, bromides, and tosylates derived from E(13-33)(+), i.e., from highly reactive carbocations, correlate excellently with the corresponding Lewis acidities and the quantum chemically calculated methyl anion affinities. This correlation does not hold for solvolyses of derivatives of the better stabilized amino-substituted benzhydrylium ions E(1-12)(+). In contrast, the correlation between electrophilic reactivities and Lewis acidities (or methyl anion affinities) is linear for all donor-substituted benzhydrylium ions E(1-21)(+), while the acceptor-substituted benzhydrylium ions E(26-33)(+) react more slowly than expected from their thermodynamic stabilities. The boundaries of linear rate-equilibrium relationships were thus defined.
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Affiliation(s)
- Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München , Butenandtstraße 5-13, Haus F, 81377 München, Germany
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31
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Thallmair S, Kowalewski M, Zauleck JPP, Roos MK, de Vivie-Riedle R. Quantum Dynamics of a Photochemical Bond Cleavage Influenced by the Solvent Environment: A Dynamic Continuum Approach. J Phys Chem Lett 2014; 5:3480-3485. [PMID: 26278596 DOI: 10.1021/jz501718t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In every day chemistry, solvents are used to influence the outcome of chemical synthesis. Electrostatic effects stabilize polar configurations during the reaction and in addition dynamic solvent effects can emerge. How the dynamic effects intervene on the ultrafast time scale is in the focus of this theoretical study. We selected the photoinduced bond cleavage of Ph2CH-PPh3(+) for which the electrostatic interactions are negligible. Elaborate ultrafast pump-probe studies already exist and serve as a reference. We compared quantum dynamical simulations with and without environment and noticed the necessity to model the influence of the solvent cage on the reactive motions of the solute. The frictional force induced by the dynamic viscosity of the solvent is implemented in the quantum mechanical formalism with a newly developed approach called the dynamic continuum ansatz. Only when the environment is included are the experimentally observed products reproduced on the subpicosecond time scale.
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Affiliation(s)
- Sebastian Thallmair
- †Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
- ‡Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität München, D-80538 München, Germany
| | - Markus Kowalewski
- †Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Julius P P Zauleck
- †Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Matthias K Roos
- †Department Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
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32
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Costa P, Fernandez-Oliva M, Sanchez-Garcia E, Sander W. The highly reactive benzhydryl cation isolated and stabilized in water ice. J Am Chem Soc 2014; 136:15625-30. [PMID: 25236711 DOI: 10.1021/ja507894x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Diphenylcarbene (DPC) shows a triplet ground-state lying approximately 3 kcal/mol below the lowest singlet state. Under the conditions of matrix isolation at 25 K, DPC reacts with single water molecules embedded in solid argon and switches its ground state from triplet to singlet by forming a strong hydrogen bond. The complex between DPC and water is only metastable, and even at 3 K the carbene center slowly inserts into the OH bond of water to form benzhydryl alcohol via quantum chemical tunneling. Surprisingly, if DPC is generated in amorphous water ice at 3 K, it is protonated instantaneously to give the benzhydryl cation. Under these conditions, the benzhydryl cation is stable, and warming to temperatures above 50 K is required to produce benzhydryl alcohol. Thus, for the first time, a highly electrophilic and extremely reactive secondary carbenium ion can be isolated in a neutral, nucleophilic environment avoiding superacidic conditions.
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Affiliation(s)
- Paolo Costa
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum , 44780 Bochum, Germany
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33
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Whitfield DM. In a glycosylation reaction how does a hydroxylic nucleophile find the activated anomeric carbon? Carbohydr Res 2014; 403:69-89. [PMID: 24962244 DOI: 10.1016/j.carres.2014.05.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 12/23/2022]
Abstract
The mechanism by which nucleophilic hydroxyls are attracted to activated glycopyranosyl donors is not known. Besides the intrinsic attraction of oxygen centred negative dipoles towards the developing electron deficiency at the anomeric carbon only a few suggestions have been given in the literature. By studying the effect on Density Functional Theory (DFT) modelled glycosylation reactions on the presence of polar additives as tested with acetonitrile two possible effects have been identified. One was noted in a previous publication (Carbohydr. Res.2012, 356, 180-190) and two further examples discovered here that suggest that a lone pair of a nucleophile approaching a donor with a β-leaving group from the α-face can act as the antiperiplanar lone pair that assists leaving group departure. This interaction starts at just under a nucleophile C-1 separation of 3Å and has an incipient bond angle of O-5-C-1-Nuc(O or N) of very close to 90° which can be at C-1 with the p-type orbital at C-1-O-5 of the incipient oxacarbenium ion, that is, the LUMO of the activated donor. The 2nd interaction is less well studied and is suggested to be a similar bonding interaction which moves β-face nucleophiles to O-Nuc-C-1-leaving groups angles close to 180°.
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Affiliation(s)
- Dennis M Whitfield
- National Research Council, Human Health Therapeutics, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada.
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34
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An F, Paul S, Ammer J, Ofial AR, Mayer P, Lakhdar S, Mayr H. Structures and Reactivities of Iminium Ions Derived from Substituted Cinnamaldehydes and Various Chiral Imidazolidin-4-ones. ASIAN J ORG CHEM 2014. [DOI: 10.1002/ajoc.201402009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Thallmair S, Fingerhut BP, de Vivie-Riedle R. Ground and Excited State Surfaces for the Photochemical Bond Cleavage in Phenylmethylphenylphosphonium Ions. J Phys Chem A 2013; 117:10626-33. [DOI: 10.1021/jp403082r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sebastian Thallmair
- Department
Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
- Lehrstuhl
für BioMolekulare Optik, Ludwig-Maximilians-Universität München, D-80538 München, Germany
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36
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Maji B, Troshin K, Mayr H. Ambidente Reaktivität von Formaldehyd-N,N-dialkylhydrazonen. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305092] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Maji B, Troshin K, Mayr H. Ambident Reactivities of FormaldehydeN,N-Dialkylhydrazones. Angew Chem Int Ed Engl 2013; 52:11900-4. [DOI: 10.1002/anie.201305092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Indexed: 11/08/2022]
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38
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Ammer J, Nolte C, Karaghiosoff K, Thallmair S, Mayer P, de Vivie-Riedle R, Mayr H. Ion-pairing of phosphonium salts in solution: C-H⋅⋅⋅halogen and C-H⋅⋅⋅π hydrogen bonds. Chemistry 2013; 19:14612-30. [PMID: 24014323 DOI: 10.1002/chem.201204561] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 06/06/2013] [Indexed: 12/15/2022]
Abstract
The (1) H NMR chemical shifts of the C(α)H protons of arylmethyl triphenylphosphonium ions in CD2 Cl2 solution strongly depend on the counteranions X(-) . The values for the benzhydryl derivatives Ph2 CHPPh3 (+) X(-) , for example, range from δH =8.25 (X(-) =Cl(-) ) over 6.23 (X(-) =BF4 (-) ) to 5.72 ppm (X(-) =BPh4 (-) ). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl(-) > Br(-) ≫ BF4 (-) > SbF6 (-) . For the less bulky derivatives PhCH2 PPh3 (+) X(-) , we also find CH⋅⋅⋅Ph interactions between C(α)H and a phenyl group of the BPh4 (-) anion, which result in upfield NMR chemical shifts of the C(α)H protons. These interactions could also be observed in crystals of (p-CF3 -C6 H4 )CH2 PPh3 (+) BPh4 (-) . However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the CH⋅⋅⋅X(-) hydrogen bonds between the phosphonium ion and anions, in particular Cl(-) or Br(-) . This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh4 (-) anions. The concentration dependence of the (1) H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2 Cl2 solution. The cation-anion interactions increase with the acidity of the C(α)H protons and the basicity of the anion. The existence of CH⋅⋅⋅X(-) hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl(-) and Br(-) salts in CD2 Cl2 solution show strong red-shifts of the CH stretch bands. The CH stretch bands of the tetrafluoroborate salt PhCH2 PPh3 (+) BF4 (-) in CD2 Cl2 , however, show a blue-shift compared to the corresponding BPh4 (-) salt.
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Affiliation(s)
- Johannes Ammer
- Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München (Germany), Fax: (+49) 89-2180-77398.
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Sailer CF, Riedle E. Photogeneration and reactions of benzhydryl cations and radicals: A complex sequence of mechanisms from femtoseconds to microseconds. PURE APPL CHEM 2013. [DOI: 10.1351/pac-con-13-04-01] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Benzhydryl radicals and cations are reactive intermediates central to the
understanding of organic reactivity. They can be generated from benzhydryl
halides by UV irradiation. We performed transient absorption (TA) measurements
over the range from femtoseconds to microseconds to unravel the complete
reaction scheme. The 290–720-nm probe range allows the unambiguous monitoring of
all fragments. The appearance of the radical is delayed to the optical
excitation, the onset of the cation signal is found even later. Ab initio
calculations show that this non-rate behavior in the 100 fs range is due to
wavepacket motion from the Franck–Condon region to two distinct conical
intersections. The rise of the optical signal with a quasi-exponential time of
300 fs is assigned to the planarization and solvation of the photoproducts. The
bond cleavage predominantly generates radical pairs. A subsequent electron
transfer (ET) transforms radical pairs into ion pairs. Due to the broad
interradical distance distribution and the distance dependence, the ET is
strongly non-exponential. Part of the ion pairs recombine geminately. The ET and
the recombination are terminated by the depletion of close pairs and diffusional
separation. The remaining free radicals and cations undergo further reactions in
the nanosecond to microsecond regime.
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Affiliation(s)
- Christian F. Sailer
- 1Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität (LMU), München, Germany
| | - Eberhard Riedle
- 1Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität (LMU), München, Germany
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40
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Ammer J, Mayr H. Photogeneration of carbocations: applications in physical organic chemistry and the design of suitable precursors. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3132] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Johannes Ammer
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 (Haus F) 81377 München Germany
| | - Herbert Mayr
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13 (Haus F) 81377 München Germany
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Lang M, Holzmeier F, Fischer I, Hemberger P. Threshold Photoionization of Fluorenyl, Benzhydryl, Diphenylmethylene, and Their Dimers. J Phys Chem A 2013; 117:5260-8. [DOI: 10.1021/jp403158z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Melanie Lang
- Institute of Physical and Theoretical
Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Fabian Holzmeier
- Institute of Physical and Theoretical
Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical
Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Patrick Hemberger
- Molecular Dynamics Group, Paul Scherrer Institut (PSI), CH-5232 Villigen PSI,
Switzerland
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Wolf TJA, Schalk O, Radloff R, Wu G, Lang P, Stolow A, Unterreiner AN. Ultrafast photoinduced dynamics of halogenated cyclopentadienes: observation of geminate charge-transfer complexes in solution. Phys Chem Chem Phys 2013; 15:6673-83. [PMID: 23443649 DOI: 10.1039/c3cp44295k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photoinduced dynamics of the fully halogenated cyclopentadienes C5Cl6 and C5Br6 have been investigated in solution and gas phase by femtosecond time-resolved spectroscopy. Both in solution and in gas phase, homolytic dissociation into a halogen radical and a C5X5 (X = Cl, Br) radical was observed. In liquid phase, solvent-dependent formation of charge transfer complexes between geminate radicals was observed for the first time. These complexes were found to be surprisingly stable and offered the opportunity to follow the dynamics of specific radical pairs. In the case of C5Cl6 in trichloroethanol, a reaction of the chlorine radical with molecules from the solvent cage was observed.
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Affiliation(s)
- T J A Wolf
- Institut für Physikalische Chemie and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
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Maji B, Baidya M, Ammer J, Kobayashi S, Mayer P, Ofial AR, Mayr H. Nucleophilic Reactivities and Lewis Basicities of 2-Imidazolines and Related N-Heterocyclic Compounds. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Sailer CF, Thallmair S, Fingerhut BP, Nolte C, Ammer J, Mayr H, Pugliesi I, de Vivie-Riedle R, Riedle E. A Comprehensive Microscopic Picture of the Benzhydryl Radical and Cation Photogeneration and Interconversion through Electron Transfer. Chemphyschem 2013; 14:1423-37. [DOI: 10.1002/cphc.201201057] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 11/09/2022]
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45
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Sailer C, Krebs N, Fingerhut B, de Vivie-Riedle R, Riedle E. Wavepacket Splitting in the First 100 fs Determines the Products from the Bond Cleavage of Diphenylmethylchloride. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20134105042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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NOKAMI T, WATANABE T, TERAO K, SOGA K, OHATA K, YOSHIDA JI. Multiple Alkylation of Thiophene Derivatives with Simple and Extended Diarylcarbenium Ion Pools. ELECTROCHEMISTRY 2013. [DOI: 10.5796/electrochemistry.81.399] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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47
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Troshin K, Mayr H. Ion Pair Dynamics: Solvolyses of Chiral 1,3-Diarylallyl Carboxylates as a Case Study. J Am Chem Soc 2012. [DOI: 10.1021/ja308670g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Konstantin Troshin
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377
München, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377
München, Germany
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48
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Ammer J, Mayr H. Solvent nucleophilicities of hexafluoroisopropanol/water mixtures. J PHYS ORG CHEM 2012. [DOI: 10.1002/poc.3064] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Johannes Ammer
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13; (Haus F); 81377; München; Germany
| | - Herbert Mayr
- Department Chemie; Ludwig-Maximilians-Universität München; Butenandtstrasse 5-13; (Haus F); 81377; München; Germany
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Nigst TA, Antipova A, Mayr H. Nucleophilic Reactivities of Hydrazines and Amines: The Futile Search for the α-Effect in Hydrazine Reactivities. J Org Chem 2012; 77:8142-55. [DOI: 10.1021/jo301497g] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Tobias A. Nigst
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377
München, Germany
| | - Anna Antipova
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377
München, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), 81377
München, Germany
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Mayr H, Lakhdar S, Maji B, Ofial AR. A quantitative approach to nucleophilic organocatalysis. Beilstein J Org Chem 2012; 8:1458-78. [PMID: 23019481 PMCID: PMC3458771 DOI: 10.3762/bjoc.8.166] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 07/31/2012] [Indexed: 12/23/2022] Open
Abstract
The key steps in most organocatalytic cyclizations are the reactions of electrophiles with nucleophiles. Their rates can be calculated by the linear free-energy relationship log k(20 °C) = s(N)(E + N), where electrophiles are characterized by one parameter (E) and nucleophiles are characterized by the solvent-dependent nucleophilicity (N) and sensitivity (s(N)) parameters.Electrophilicity parameters in the range -10 < E < -5 were determined for iminium ions derived from cinnamaldehyde and common organocatalysts, such as pyrrolidines and imidazolidinones, by studying the rates of their reactions with reference nucleophiles. Iminium activated reactions of α,β-unsaturated aldehydes can, therefore, be expected to proceed with nucleophiles of 2 < N < 14, because such nucleophiles are strong enough to react with iminium ions but weak enough not to react with their precursor aldehydes. With the N parameters of enamines derived from phenylacetaldehyde and MacMillan's imidazolidinones one can rationalize why only strong electrophiles, such as stabilized carbenium ions (-8 < E < -2) or hexachlorocyclohexadienone (E = -6.75), are suitable electrophiles for enamine activated reactions with imidazolidinones. Several mechanistic controversies concerning iminium and enamine activated reactions could thus be settled by studying the reactivities of independently synthesized intermediates.Kinetic investigations of the reactions of N-heterocyclic carbenes (NHCs) with benzhydrylium ions showed that they have similar nucleophilicities to common organocatalysts (e.g., PPh(3), DMAP, DABCO) but are much stronger (100-200 kJ mol(-1)) Lewis bases. While structurally analogous imidazolylidenes and imidazolidinylidenes have comparable nucleophilicities and Lewis basicities, the corresponding deoxy Breslow intermediates differ dramatically in reactivity. The thousand-fold higher nucleophilicity of 2-benzylidene-imidazoline relative to 2-benzylidene-imidazolidine is explained by the gain of aromaticity during electrophilic additions to the imidazoline derivatives. O-Methylated Breslow intermediates are a hundred-fold less nucleophilic than deoxy Breslow intermediates.
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Affiliation(s)
- Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandstr. 5-13 (Haus F), 81377 München, Germany
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