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Abdellaoui C, Hermanns V, Reinfelds M, Scheurer M, Dreuw A, Heckel A, Wachtveitl J. A long-lived fluorenyl cation: efficiency booster for uncaging and photobase properties. Phys Chem Chem Phys 2022; 24:5294-5300. [PMID: 35174833 DOI: 10.1039/d1cp05292f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photochemistry of fluorenols has been of special interest for many years. This is because both the fluorenol and the fluorenyl cation are antiaromatic in the ground state due to their 4n π-electrons according to the Hückel rule. The photolysis reaction of various fluorene derivatives takes place via a cation intermediate and is preferred due to its excited state aromaticity. Here we present an extremely long-lived fluorenyl cation and its effects on the uncaging of various leaving groups. We analyze the relationship between uncaging quantum yields of fluorene-based cages and the longevity of their fluorenyl cations with different spectroscopic methods in the steady state and on an ultrafast time scale and find that the uncaging quantum yield rises with the stability of the cation. In contrast to previous reports, the cation can be observed on a time scale of minutes, even in moderately protic solvents as methanol and ethanol. The stability of this cation depends on the dimethylamino-substituents on the fluorene scaffold and the properties of the solvent. In addition, with bis-dimethylamino fluorenol, a photobase is introduced that expands the small group of known photoinduced hydroxide emitters.
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Affiliation(s)
- Chahinez Abdellaoui
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt am Main 60438, Germany.
| | - Volker Hermanns
- Institute of Organic Chemistry, Goethe-University Frankfurt, Frankfurt am Main 60438, Germany.
| | - Matiss Reinfelds
- Institute of Organic Chemistry, Goethe-University Frankfurt, Frankfurt am Main 60438, Germany. .,Institute of Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Graz 8010, Austria.
| | - Maximilian Scheurer
- Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg 69120, Germany.
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg 69120, Germany.
| | - Alexander Heckel
- Institute of Organic Chemistry, Goethe-University Frankfurt, Frankfurt am Main 60438, Germany.
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt am Main 60438, Germany.
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2
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Follet E, Mayer P, Berionni G. Structures, Lewis Acidities, Electrophilicities, and Protecting Group Abilities of Phenylfluorenylium and Tritylium Ions. Chemistry 2017; 23:623-630. [PMID: 27723164 DOI: 10.1002/chem.201603963] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Indexed: 11/06/2022]
Abstract
The isolation, characterization, and the first X-ray structures of a fluorenylium ion and its Lewis adducts with nitrogen- and phosphorus-centered Lewis bases are reported. Kinetics of the reactions of a series of fluorenylium ions with reference π-, σ-, and n-nucleophiles of various sizes and nucleophilicities allowed the interplay between electronic and structural parameters on the electrophilicities of these planarized tertiary carbenium ions to be elucidated. Structure-reactivity correlations and extensive comparisons of their reactivities with those of di- and triarylcarbenium ions are described. Quantitative determination of the electrofugalities of fluorenylium ions revealed to which extent they are complementing tritylium ions as protecting groups and how their tuning is possible. Determination of the equilibrium constants of the Lewis adducts formation between pyridines of calibrated Lewis basicities and phenylfluorenylium and tritylium ions allowed the determination of their Lewis acidities and to showcase the potential of these carbon-centered Lewis acids in catalysis.
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Affiliation(s)
- Elsa Follet
- 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
| | - Guillaume Berionni
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377, München, Germany
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3
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Huang D, Yang W, Zhang J, Wang X, Wang X, Hu Y. Lewis acid-catalyzed tandem synthesis of 9-sulfonylamino- and 9-arylfluorenes. RSC Adv 2016. [DOI: 10.1039/c6ra03889a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A Lewis acid-catalyzed three-step tandem synthesis of 9-arylfluorene was developed by simply heating a mixture of 2-formyl biphenyl, TsNCO and an arene.
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Affiliation(s)
- Dayun Huang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Weiguang Yang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Jianlan Zhang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Xuesong Wang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Xinyan Wang
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
| | - Yuefei Hu
- Department of Chemistry
- Tsinghua University
- Beijing 100084
- P. R. China
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4
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Chan J, Tang A, Bennet AJ. A Stepwise Solvent-Promoted SNi Reaction of α-d-Glucopyranosyl Fluoride: Mechanistic Implications for Retaining Glycosyltransferases. J Am Chem Soc 2011; 134:1212-20. [DOI: 10.1021/ja209339j] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jefferson Chan
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6,
Canada
| | - Ariel Tang
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6,
Canada
| | - Andrew J. Bennet
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6,
Canada
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5
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Bancerz M, Huck LA, Leigh WJ, Mladenova G, Najafian K, Zeng X, Lee-Ruff E. Photochemical generation of thiophene analogs of 9-fluorenyl cations. J PHYS ORG CHEM 2010. [DOI: 10.1002/poc.1754] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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Stabilities and Reactivities of Carbocations. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2010. [DOI: 10.1016/s0065-3160(08)44002-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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7
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Fuchibe K, Mitomi K, Suzuki R, Akiyama T. CC Coupling Reactions of Superstrong CF3Groups with C(sp2)-H Bonds: Reactivity and Synthetic Utility of Zero-Valent Niobium Catalyst. Chem Asian J 2008; 3:261-71. [DOI: 10.1002/asia.200700333] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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8
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Winkler M, Sander W. Generation and Reactivity of the Phenyl Cation in Cryogenic Argon Matrices: Monitoring the Reactions with Nitrogen and Carbon Monoxide Directly by IR Spectroscopy. J Org Chem 2006; 71:6357-67. [PMID: 16901116 DOI: 10.1021/jo0603678] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The phenyl cation 1 has been prepared by co-deposition of iodobenzene 6 or bromobenzene 7 with a microwave-induced argon plasma and characterized by IR spectroscopy in cryogenic argon matrices. The cation can clearly be identified by its strongest absorption at 3110 cm(-1) that is rapidly bleached upon visible light irradiation. This characteristic band is observed neither in the conventional photochemistry of 6 or 7 nor in discharge experiments with alkyl halides or chlorobenzene. The latter finding is in line with energetic considerations. According to density functional theory (DFT) computations, the strongest absorption of 1 is caused by a C-H stretching vibration that involves almost entirely the ortho-hydrogens. This is confirmed by isotopic labeling experiments. Co-deposition of halobenzene/N2 mixtures leads to a decrease of the 3110 cm(-1) absorption, whereas several new signals are detected in the 2200-2400 cm(-1) range of the IR spectrum. Annealing of a matrix that contains 1 and 1% N2 leads to an increase of a broad band at 2260 cm(-1) that is assigned to the benzenediazonium ion 2. A sharp signal at 2327 cm(-1) that had previously been assigned to the N-N stretching vibration of 2 is due to molecular nitrogen. The mechanism that triggers the IR activity of N2 is not yet understood. Annealing of a matrix that contains 1 and 0.5% CO leads to an increase of a broad band at 2217 cm(-1) that is considerably stronger than the 2260 cm(-1) absorption of 2. This signal is assigned to the C-O stretching vibration of the benzoyl cation 12, in excellent agreement with previous investigations of 12 in superacidic media. Some consequences of the measured frequencies with regard to bonding in 2 and 12 are discussed.
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Affiliation(s)
- Michael Winkler
- Lehrstuhl für Organische Chemie II der Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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9
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The Gomberg-type dimerization of bifluorenylidene radicals: an X-ray crystallographic investigation. Tetrahedron Lett 2003. [DOI: 10.1016/j.tetlet.2003.09.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Photogeneration of quinone methide-type intermediates from pyridoxine and derivatives. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(01)00654-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Pezacki JP, Shukla D, Lusztyk J, Warkentin J. Lifetimes of Dialkylcarbocations Derived from Alkanediazonium Ions in Solution: Cyclohexadienyl Cations as Kinetic Probes for Cation Reactivity1. J Am Chem Soc 1999. [DOI: 10.1021/ja9840807] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- John Paul Pezacki
- Contribution from the Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and the Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6
| | - Deepak Shukla
- Contribution from the Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and the Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6
| | - Janusz Lusztyk
- Contribution from the Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and the Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6
| | - John Warkentin
- Contribution from the Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and the Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6
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12
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Steenken S, Ashokkumar M, Maruthamuthu P, McClelland RA. Making Photochemically Generated Phenyl Cations Visible by Addition to Aromatics: Production of Phenylcyclohexadienyl Cations and Their Reactions with Bases/Nucleophiles. J Am Chem Soc 1998. [DOI: 10.1021/ja980712d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. Steenken
- Contribution from the Max-Planck-Institut für Strahlenchemie, D-45413 Mülheim, Germany, and Department of Chemistry, University of Toronto, Canada M5S 1A1
| | - M. Ashokkumar
- Contribution from the Max-Planck-Institut für Strahlenchemie, D-45413 Mülheim, Germany, and Department of Chemistry, University of Toronto, Canada M5S 1A1
| | - P. Maruthamuthu
- Contribution from the Max-Planck-Institut für Strahlenchemie, D-45413 Mülheim, Germany, and Department of Chemistry, University of Toronto, Canada M5S 1A1
| | - R. A. McClelland
- Contribution from the Max-Planck-Institut für Strahlenchemie, D-45413 Mülheim, Germany, and Department of Chemistry, University of Toronto, Canada M5S 1A1
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13
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Macknight E, McClelland RA. A photochemical retro-Friedel–Crafts alkylation. Rapid rearrangement of cyclohexadienyl cations. CAN J CHEM 1996. [DOI: 10.1139/v96-282] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This paper reports the use of laser flash photolysis (LFP) techniques to show that cyclohexadienyl cations (σ complexes) of the Friedel–Crafts reaction of 1,3-dimethoxybenzene and the diphenylmethyl cation rearrange on the ns time scale without separating the aromatic compound and the electrophile. This is demonstrated through a study of the photochemical behaviour of 2-diphenylmethyl-1,3-dimethoxybenzene (4) in 1,1,1,3,3,3-hexafIuoroisopropyl alcohol (HFIP). Derivatives of 1,3-dimethoxybenzene have previously been found to selectively protonate at C2 upon excitation in HFIP, and indeed the principal products with 4 are 1,3-dimethoxybenzene (6) and Ph2CHOCH(CF3)2 (7), the species expected if the cyclohexadienyl cation formed in the C2 protonation cleaved Ph2CH+. These products are, however, accompanied by 4-diphenylmethyl- 1,3-dimethoxybenzene (8), a rearranged isomer of 4. A portion of this product is explained by the combination of Ph2CH+ and 1,3-dimethoxybenzene as the latter accumulates during the irradiation. However, 11.5% of 8 is also seen upon extrapolation to zero time. LFP experiments on the ps time scale reveal that the C2 protonated cation, the 1-diphenylmethyl-2,6-dimethoxybenzenium ion (5), is formed within 100–200 ps, and reacts with k = 9 × 108 s−1, with absorbance for Ph2CH+ growing in as 5 decays. LFP studies on the ns time scale reveal that there is a second quantity of Ph2CH+ that grows in, with k = 5.0 × 105 s−1. The precursor for this has been identified as the 1-diphenylmethyl-2,4-dimethoxybenzenium ion (10), the thermodynamically more stable isomer of 5. A mechanistic model is proposed in which excited 4 is C2 protonated in HFIP with k ≥ 1 × 1010 s−1 to form 5, which loses Ph2CH+ with k = 3 × 108 s−1 in competition with rearrangement to 10 with k = 6 x 108 s−1. The cation 10 serves as the second source of Ph2CH+, losing Ph2CH+ with k = 4 × 105 s−1; in competition 10 is deprotonated by HFIP to give 8 with k = 8 × 104 s−1. The 11.5 % of the rearranged 8 that is observed at zero conversion is thus shown to come from an intramolecular pathway in which the key step is the migration of a diphenylmethyl group without separation: 4 → 4* → 5 → 10 → 8. Key words: cyclohexadienyl, photoprotonation, Friedel–Crafts, diphenylmethyl, 1,3-dimethoxybenzene.
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