1
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Bhowmick T, Orthaber A. Main Group Pentafulvenes: Challenges and Opportunities in Heavy Main Group Isolobal Substitution of Pentafulvene. Chemphyschem 2024; 25:e202300940. [PMID: 38709950 DOI: 10.1002/cphc.202300940] [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: 12/09/2023] [Revised: 05/06/2024] [Accepted: 05/06/2024] [Indexed: 05/08/2024]
Abstract
Heterofulvenes based on isolobal substitution of carbon fragments by (heavier) main group motifs provide a rich source of structurally interesting building blocks with electronic situations that can vastly differ from all-carbon congeners. Group 13, heavier 14 & 16 fulvenes are rare and pose significant stability challenges, while group 15 derivatives, particularly phosphorus and arsenic, have led to many derivatives with intriguing opto-electronic properties.
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Affiliation(s)
- Toma Bhowmick
- Department of Chemistry Ångström laboratories, Uppsala University, Box 523, 75120, Uppsala, Sweden
| | - Andreas Orthaber
- Department of Chemistry Ångström laboratories, Uppsala University, Box 523, 75120, Uppsala, Sweden
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2
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Zhu L, Kinjo R. Crystalline 2π Aromatic Azadiboriridinylium: A BN Analogue of Cyclopropenylium Cation. Angew Chem Int Ed Engl 2023; 62:e202312949. [PMID: 37828652 DOI: 10.1002/anie.202312949] [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: 09/01/2023] [Revised: 09/28/2023] [Accepted: 10/09/2023] [Indexed: 10/14/2023]
Abstract
N-Substitution of a thermally unstable diboratriazole 1 with a trimethylsilyl group affords a remarkably stable diboratriazole derivative 2. Ring contraction of 2 with an N-heterocyclic carbene accompanied by the release of N2 as well as 1,4-hydrogen shift affords a carbene-stabilized azadiboriridine 3. Abstraction of the H-B3mem hydride in 3 with methyl trifluoromethanesulfonate leads to the isolation of a hitherto unknown azadiboriridinylium 4, the first BN analogue of cyclopropenylium cation. X-ray diffraction analysis and computational studies confirmed the delocalization of π electrons over the B2 N three-membered ring, indicating the 2π aromatic feature. Compound 4 undergoes ring expansion reactions with azobenzene and pyridazine to furnish triazadiborolidinylium species 5 and 6, the latter of which possesses a cationic B2 N3 ring with a pronounced 6π aromatic property. Moreover, the reaction of 4 with a diazo compound produces a cationic B2 N3 C pentafulvene derivative 7.
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Affiliation(s)
- Lizhao Zhu
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Nanyang Link 21, Singapore, 637371, Singapore
| | - Rei Kinjo
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Nanyang Link 21, Singapore, 637371, Singapore
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3
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Wieczorkiewicz PA, Zborowski KK, Krygowski TM, Szatylowicz H. Substituent Effect versus Aromaticity─A Curious Case of Fulvene Derivatives. J Org Chem 2023; 88:14775-14780. [PMID: 37773323 PMCID: PMC10594647 DOI: 10.1021/acs.joc.3c01539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Indexed: 10/01/2023]
Abstract
A computational study on amino- and nitro-substituted penta- and heptafulvenes reveals the interplay between the aromaticity and the substituent effect (SE). Ring substitution alone has little influence on the aromaticity, but in combination with an exo substituent of opposite properties, it substantially enhances the cyclic π-electron delocalization. Despite the SE being stronger for β substitution, only γ substitution leads to higher aromaticity. An explanation is provided by the electron density of delocalized bonds (EDDB) method, which proves to be a valuable tool in analyzing both cyclic delocalization and the SE.
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Affiliation(s)
- Pawel A. Wieczorkiewicz
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw 00-664, Poland
| | - Krzysztof K. Zborowski
- Faculty
of Chemistry, Jagiellonian University in
Kraków, Gronostajowa
2, Kraków 30-387, Poland
| | - Tadeusz M. Krygowski
- Department
of Chemistry, University of Warsaw, Pasteura 1, Warsaw 02-093, Poland
| | - Halina Szatylowicz
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw 00-664, Poland
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4
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Chrysochos N, Pätsch S, Elvers BJ, Krummenacher I, Nandeshwar M, Prabusankar G, Braunschweig H, Schulzke C, Ravat P, Jana A. Introducing an orthogonally polarized electron-rich alkene: synthesis of a zwitterionic boron-containing π-conjugated system. Chem Commun (Camb) 2023; 59:12350-12353. [PMID: 37767978 DOI: 10.1039/d3cc03975g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
The synthesis of an alkene is reported which is concurrently twisted (twist angle = 86.6(8)°), push-pull (dipole moment = 7.48 D), and electron-rich (E1/2 = -1.45 V and -0.52 V vs. Fc/Fc+) in nature, comprising a unique trinity combination for the alkene class of compounds. Subsequently, this newly synthesized alkene-motif was used as a donor for the synthesis of a zwitterionic boron-containing π-conjugated compound (dipole moment = 12.17 D) through an intramolecular charge transfer process exploiting the π-conjugated donor-acceptor system.
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Affiliation(s)
- Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500107, India.
| | - Sebastian Pätsch
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489, Greifswald, Germany.
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489, Greifswald, Germany.
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Muneshwar Nandeshwar
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi-502284, India.
| | - Ganesan Prabusankar
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi-502284, India.
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489, Greifswald, Germany.
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500107, India.
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5
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Tortajada A, Bole LJ, Mu M, Stanford M, Peñas-Defrutos MN, García-Melchor M, Hevia E. Sodium mediated deprotonative borylation of arenes using sterically demanding B(CH 2SiMe 3) 3: unlocking polybasic behaviour and competing lateral borane sodiation. Chem Sci 2023; 14:6538-6545. [PMID: 37350840 PMCID: PMC10283504 DOI: 10.1039/d3sc01705b] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/04/2023] [Indexed: 06/24/2023] Open
Abstract
The deprotonative metalation of organic molecules has become a convenient route to prepare functionalised aromatic substrates. Amongst the different metallating reagents available, sodium bases have recently emerged as a more sustainable and powerful alternative to their lithium analogues. Here we report the study of the sterically demanding electrophilic trap B(CH2SiMe3)3 for the deprotonative borylation of arenes using NaTMP (TMP = 2,2,6,6-tetramethylpiperidide) in combination with tridentate Lewis donor PMDETA (PMDETA = N,N,N',N'',N''-pentamethyldiethylenetriamine). Using anisole and benzene as model substrates, unexpected polybasic behaviour has been uncovered, which enables the formal borylation of two equivalents of the relevant arene. The combination of X-ray crystallographic and NMR monitoring studies with DFT calculations has revealed that while the first B-C bond forming process takes place via a sodiation/borylation sequence to furnish [(PMDETA)NaB(Ar)(CH2SiMe3)3] species, the second borylation step is facilitated by the formation of a borata-alkene intermediate, without the need of an external base. For non-activated benzene, it has also been found that under stoichimetric conditions the lateral sodiation of B(CH2SiMe3)3 becomes a competitive reaction pathway furnishing a novel borata-alkene complex. Showing a clear alkali-metal effect, the use of the sodium base is key to access this reactivity, while the metalation/borylation of the amine donor PMDETA is observed instead when LiTMP is used.
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Affiliation(s)
- Andreu Tortajada
- Department für Chemie und Biochemie, Universität Bern Freiestrasse 3 3012 Bern Switzerland
| | - Leonie J Bole
- Department für Chemie und Biochemie, Universität Bern Freiestrasse 3 3012 Bern Switzerland
| | - Manting Mu
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green Dublin 2 Ireland
| | - Martin Stanford
- Department für Chemie und Biochemie, Universität Bern Freiestrasse 3 3012 Bern Switzerland
| | - Marconi N Peñas-Defrutos
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green Dublin 2 Ireland
- IU CINQUIMA/Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid 47071-Valladolid Spain
| | - Max García-Melchor
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green Dublin 2 Ireland
| | - Eva Hevia
- Department für Chemie und Biochemie, Universität Bern Freiestrasse 3 3012 Bern Switzerland
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6
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Bao M, Dai Y, Liu C, Su Y. Acid/Base-Free Acyclic Anionic Oxoborane and Iminoborane Bearing Diboryl Groups. Inorg Chem 2022; 61:11137-11142. [PMID: 35815522 DOI: 10.1021/acs.inorgchem.2c00966] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Anionic oxoboranes and neutral iminoboranes, which are isoelectronic to ketones and alkynes, respectively, have attracted much attention because of their unique structures and various reactivity. However, acid/base-free oxoboranes and iminoboranes are still limited, and readily accessible examples with diverse electronic and steric characteristics are highly desirable. Herein, we report the first syntheses of the acyclic anionic oxoborane 2 and iminoborane 4 bearing two boryl ligands, both of which are acid/base-free. Spectroscopic analysis, X-ray crystallography, and theoretical calculations reveal that 2 and 4 possess a polarized terminal B═O double bond and central B≡N triple bond, respectively.
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Affiliation(s)
- Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, P. R. China.,State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210023, P. R. China
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7
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Golfmann M, Sindlinger CP. Assessing an Elusive 3,4‐Dimethyl‐Chloroborole. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200359] [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)
- Maxim Golfmann
- Institut für Anorganische Chemie Georg-August Universität Göttingen Tammannstr. 4 37077 Göttingen Germany
- Present address: Institut für Organische und Biomolekulare Chemie Georg-August Universität Göttingen Tammannstr. 2 37077 Göttingen Germany
| | - Christian P. Sindlinger
- Institut für Anorganische Chemie RWTH Aachen University Landoltweg 1a D-52074 Aachen Germany
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8
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Škoch K, Chen C, Daniliuc CG, Kehr G, Erker G. A deprotonation pathway to reactive [B]CH 2 boraalkenes. Dalton Trans 2022; 51:7695-7704. [PMID: 35521694 DOI: 10.1039/d2dt01193j] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The BH compounds IMes(ArF)BH(NTf2) (ArF: C6F5 or FpXyl) were converted to the IMes(ArF)BCH2 boraalkenes in a three step reaction sequence of B-methylation with methyllithium, hydride abstraction and deprotonation. The BCH2 boraalkenes reacted with elemental sulfur to give a thiaborirane product. They underwent [2+2] cycloaddition reactions with carbon dioxide or sulfur dioxide to give four-membered boron containing heterocycles. The boraalkenes added strongly Lewis acidic boranes at their CH2 carbon atoms. The corresponding HB(C6F5)2/boraalkene adduct reduced carbon monoxide to a -OCH(C6F5)- moiety inside a five-membered heterocycle at the B-CH2-B template. The boraalkenes reacted with the [(Me2S)AuCl] reagent to form the corresponding (boraalkene)AuCl complexes.
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Affiliation(s)
- Karel Škoch
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany.
| | - Chaohuang Chen
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany.
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany.
| | - Gerald Kehr
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany.
| | - Gerhard Erker
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany.
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9
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Dankert F, Fischer M, Hering-Junghans C. Modulating the reactivity of phosphanylidenephosphoranes towards water with Lewis acids. Dalton Trans 2022; 51:11267-11276. [DOI: 10.1039/d2dt01575g] [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
Phosphanylidenephosphoranes of the type R−P(PR’3), also known as phospha-Wittig reagents, can be utilized in a variety of bond activation reactions exploiting their phosphinidenoid reactivity. In here, we thoroughly show that...
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10
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Abstract
Structurally authenticated free B-alkyl boroles are presented and electronic implications of alkyl substitution were assessed. Deprotonation of a boron-bound exocyclic methyl group in a B-methyl borole yields the first 5-boratafulvene anion-an isomer to boratabenzene. Boratafulvene was structurally characterized and its electronic structure probed by DFT calculations. The pKa value of the exocyclic B-CH3 in a set of boroles was computationally approximated and confirmed a pronounced acidic character caused by the boron atom embedded in an anti-aromatic moiety. The non-aromatic boratafulvene reacts as a C-centered nucleophile with the mild electrophile Me3 SnCl to give a stannylmethyl borole, regenerating the anti-aromaticity. As nucleophilic synthons for boroles, boratafulvenes thus open an entirely new avenue for synthetic strategies toward this highly reactive class of heterocycles. Boratafulvene reacts as a methylene transfer reagent in a bora-Wittig-type reaction generating a borole oxide.
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Affiliation(s)
- Tobias Heitkemper
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Leonard Naß
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Christian P. Sindlinger
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
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