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Maurya JP, Swain SS, Ramasastry SSV. Phosphine-promoted intramolecular Rauhut-Currier/Wittig reaction cascade to access (hetero)arene-fused diquinanes. Org Biomol Chem 2024; 22:5718-5723. [PMID: 38919118 DOI: 10.1039/d4ob00984c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
We describe the first phosphine-promoted intramolecular Rauhut-Currier reaction that triggers an intramolecular Wittig process assembling new classes of diquinanes. The one-pot strategy provides ready access to simple diquinanes and various (hetero)arene-fused diquinanes incorporated with up to two contiguous all-carbon quaternary centers under metal-free and neutral conditions. We showcased the generality of the method on a broad range of substrates and demonstrated its synthetic utility in accessing various advanced intermediates relevant to natural product synthesis and material science.
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Affiliation(s)
- Jay Prakash Maurya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Punjab 140306, India.
| | - Subham S Swain
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Punjab 140306, India.
| | - S S V Ramasastry
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Punjab 140306, India.
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2
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Kleinpeter E, Koch A. Identification and quantification of local antiaromaticity in polycyclic aromatic hydrocarbons (PAHs) based on the magnetic criterion. Org Biomol Chem 2024; 22:3035-3044. [PMID: 38534070 DOI: 10.1039/d4ob00114a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
The spatial magnetic properties, through-space NMR shieldings (TSNMRSs, actually the ring current effect in 1H NMR spectroscopy), of a selection of entirely antiaromatic and aromatic polycyclic conjugated hydrocarbons (PCHs), and aromatic PCHs with antiaromatic components, have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSSs) of various sizes and directions. Using both in-plane and above/below-plane ICSS data, polycyclic aromatic hydrocarbons can be readily distinguished from polycyclic antiaromatic ones, even when antiaromatic components are present in the polycyclic aromatic hydrocarbons (PAHs). These antiaromatic zones can also be attributed to internal components of the in-plane deshielding belt present in aromatic compounds and possible partial antiaromatic ring current effects in the same place. This makes it possible to unequivocally confirm correctly assigned or adjust incorrectly assigned antiaromaticity of individual rings in the same molecule.
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Affiliation(s)
- Erich Kleinpeter
- Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Golm), Germany.
| | - Andreas Koch
- Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Golm), Germany.
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3
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Gazdag T, Meiszter E, Mayer PJ, Holczbauer T, Ottosson H, Maurer AB, Abrahamsson M, London G. An Exploration of Substituent Effects on the Photophysical Properties of Monobenzopentalenes. Chemphyschem 2024; 25:e202300737. [PMID: 38284145 DOI: 10.1002/cphc.202300737] [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: 10/09/2023] [Revised: 12/18/2023] [Accepted: 01/26/2024] [Indexed: 01/30/2024]
Abstract
Monobenzopentalenes have received moderate attention compared to dibenzopentalenes, yet their accessibility as stable, non-symmetric structures with diverse substituents could be interesting for materials applications, including molecular photonics. Recently, monobenzopentalene was considered computationally as a potential chromophore for singlet fission (SF) photovoltaics. To advance this compound class towards photonics applications, the excited state energetics must be characterized, computationally and experimentally. In this report we synthesized a series of stable substituted monobenzopentalenes and provided the first experimental exploration of their photophysical properties. Structural and opto-electronic characterization revealed that all derivatives showed 1H NMR shifts in the olefinic region, bond length alternation in the pentalene unit, low-intensity absorptions reflecting the ground-state antiaromatic character and in turn the symmetry forbidden HOMO-to-LUMO transitions of ~2 eV and redox amphotericity. This was also supported by computed aromaticity indices (NICS, ACID, HOMA). Accordingly, substituents did not affect the fulfilment of the energetic criterion of SF, as the computed excited-state energy levels satisfied the required E(S1)/E(T1)>2 relationship. Further spectroscopic measurements revealed a concentration dependent quenching of the excited state and population of the S2 state on the nanosecond timescale, providing initial evidence for unusual photophysics and an alternative entry point for singlet fission with monobenzopentalenes.
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Affiliation(s)
- Tamás Gazdag
- MTA TTK Lendület Functional Organic Materials Research Group, Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, 1117, Budapest, Magyar tudósok krt. 2, Hungary
- Hevesy György PhD School of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/a, Budapest, 1117, Hungary
| | - Enikő Meiszter
- MTA TTK Lendület Functional Organic Materials Research Group, Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, 1117, Budapest, Magyar tudósok krt. 2, Hungary
- Department of Organic Chemistry and Technology, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111, Budapest, Hungary
| | - Péter J Mayer
- MTA TTK Lendület Functional Organic Materials Research Group, Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, 1117, Budapest, Magyar tudósok krt. 2, Hungary
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20, Sweden
| | - Tamás Holczbauer
- Chemical Crystallography Research Laboratory and Stereochemistry Research Group, Institute for Organic Chemistry, HUN-REN Research Centre for Natural Sciences, 1117, Budapest, Magyar tudósok krt. 2, Hungary
| | - Henrik Ottosson
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20, Sweden
| | - Andrew B Maurer
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Maria Abrahamsson
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Gábor London
- MTA TTK Lendület Functional Organic Materials Research Group, Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, 1117, Budapest, Magyar tudósok krt. 2, Hungary
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Karas LJ, Jalife S, Viesser RV, Soares JV, Haley MM, Wu JI. Tetra-tert-butyl-s-indacene is a Bond-Localized C 2h Structure and a Challenge for Computational Chemistry. Angew Chem Int Ed Engl 2023; 62:e202307379. [PMID: 37467313 PMCID: PMC10528983 DOI: 10.1002/anie.202307379] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Whether tetra-tert-butyl-s-indacene is a symmetric D2h structure or a bond-alternating C2h structure remains a standing puzzle. Close agreement between experimental and computed proton chemical shifts based on minima structures optimized at the M06-2X, ωB97X-D, and M11 levels confirm a bond-localized C2h symmetry, which is consistent with the expected strong antiaromaticity of TtB-s-indacene.
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Affiliation(s)
- Lucas J Karas
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Said Jalife
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Renan V Viesser
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - João V Soares
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Michael M Haley
- Department of Chemistry & Biochemistry and the Materials Science Institute, University of Oregon, Eugene, OR 97403-1253, USA
| | - Judy I Wu
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
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Mondal S, Ballav T, Tofayel TSM, Ganesh V. Bis-benzofulvenes: Synthesis and Studies on Their Optoelectronic Properties. Org Lett 2023. [PMID: 37205608 DOI: 10.1021/acs.orglett.3c01318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We report the synthesis of bis-benzofulvenes and the studies on their optical and redox properties. Bis-benzofulvenes were achieved through the Pd-catalyzed intramolecular Heck coupling followed by Ni0-mediated C(sp2)-Br dimerization. Low optical and electrochemical energy gaps of 2.05 and 1.68 eV were achieved by tuning the substituent on the exomethylene unit and the aromatic ring. The observed trends in the energy gaps were compared, and the frontier molecular orbitals were visualized using the density functional theory.
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Affiliation(s)
- Sourav Mondal
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Tamal Ballav
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | | | - Venkataraman Ganesh
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
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