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Cosby TPL, Bhattacharjee A, Henneberry SK, LeBlanc J, Caputo CB. Unlocking Lewis acidity via the redox non-innocence of a phenothiazine-substituted borane. Chem Commun (Camb) 2024; 60:5391-5394. [PMID: 38586997 DOI: 10.1039/d4cc01059k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
We describe a new approach to enhancing Lewis acidity, through the single electron oxidation of a borane with a pendant phenothiazine. This results in the formation of a persistent radical cation with increased electrophilicity. Computational and experimental studies indicate this radical cation significantly enhances the Lewis acidity and catalytic activity compared to its neutral analog. These results illustrate the viability of this approach in turning on the Lewis acidity of relatively inert boranes.
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Affiliation(s)
- Taylor P L Cosby
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Avik Bhattacharjee
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Samantha K Henneberry
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Jesse LeBlanc
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Christopher B Caputo
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
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2
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Fukazawa M, Takahashi F, Kurogi T, Yorimitsu H. Sodium-Mediated Reductive C-C Bond Cleavage Assisted by Boryl Groups. Chem Asian J 2024; 19:e202400100. [PMID: 38385830 DOI: 10.1002/asia.202400100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 02/23/2024]
Abstract
In contrast to the well-established oxidative C=C double bond cleavage to give the corresponding carbonyl compounds, little is known about reductive C=C double bond cleavage. Here we report that C-C single bond cleavage in 1,2-diaryl-1,2-diborylethanes proceeds by reduction with sodium metal to yield α-boryl benzylsodium species. In combination with our previous reductive diboration of stilbenes, the overall transformation represents reductive cleavage of the C=C double bonds of stilbene to yield α-boryl-α-sodiated toluenes. This reductive two-step C=C double bond cleavage is applicable to ring-opening or ring-expansion reactions of polycyclic aromatic hydrocarbons.
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Affiliation(s)
- Mizuki Fukazawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Sakyo-ku, 606-8502 Kyoto, Japan
| | - Fumiya Takahashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Sakyo-ku, 606-8502 Kyoto, Japan
| | - Takashi Kurogi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Sakyo-ku, 606-8502 Kyoto, Japan
| | - Hideki Yorimitsu
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Sakyo-ku, 606-8502 Kyoto, Japan
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3
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Li J, Tanaka H, Imagawa T, Tsushima T, Nakamoto M, Tan J, Yoshida H. Ethynyl-B(dan) in [3+2] Cycloaddition and Larock Indole Synthesis: Synthesis of Stable Boron-Containing Heteroaromatic Compounds. Chemistry 2024; 30:e202303403. [PMID: 38109084 DOI: 10.1002/chem.202303403] [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: 10/16/2023] [Indexed: 12/19/2023]
Abstract
The cycloaddition of nitrile oxides with ethynyl-B(dan) (dan=naphthalene-1,8-diaminato) allowed the facile preparation of diverse isoxazolyl-B(dan) compounds, all of which displayed excellent protodeborylation-resistant properties. The dan-installation on the boron center proves vital to the high stability of the products as well as the perfect regioselectivity arising from hydrogen bond-directed orientation in the cycloaddition. The diminished boron-Lewis acidity of ethynyl-B(dan) also renders it amenable to azide-alkyne cycloaddition, Larock indole synthesis and related heteroannulations. The obtained boron-containing triazole, indoles, benzofuran and indenone exhibit sufficient resistance toward protodeborylation. Despite the commonly accepted transmetalation-inactive property derived from the diminished Lewis acidity, the synthesized heteroaryl-B(dan) compound was still found to be convertible to the oligoarene via sequential Suzuki-Miyaura coupling.
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Affiliation(s)
- Jialun Li
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
| | - Hideya Tanaka
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
| | - Taiki Imagawa
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
| | - Takumi Tsushima
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
| | - Masaaki Nakamoto
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
| | - Jiajing Tan
- College of Chemistry, Beijing University of Chemical Technology (BUCT), Beijing, 100029, China
| | - Hiroto Yoshida
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
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Timoshkin AY. The Field of Main Group Lewis Acids and Lewis Superacids: Important Basics and Recent Developments. Chemistry 2024; 30:e202302457. [PMID: 37752859 DOI: 10.1002/chem.202302457] [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: 07/30/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 09/28/2023]
Abstract
New developments in the field of Lewis acidity are highlighted, with the focus of novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements. Several important basics, illustrated by modern examples (classification of Donor-Acceptor (DA) complexes, amphoteric nature of any compound in terms of DA interactions, reorganization energies of main group Lewis acids and the role of the energies of frontier orbitals) are presented and discussed. It is emphasized that the Lewis acidity phenomena are general and play vital role in different areas of chemistry: from weak "atomophilic" interactions to the complexes of Lewis superacids.
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Affiliation(s)
- Alexey Y Timoshkin
- Institute of Chemistry, St. Petersburg State University, 199034, Universitetskaya emb. 7/9, St. Petersburg, Russia
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Tomota K, Izumi Y, Nakanishi K, Nakamoto M, Yoshida H. Efficient one-pot synthesis of dan-substituted organo- and silyl-boron compounds. Org Biomol Chem 2023. [PMID: 37161742 DOI: 10.1039/d3ob00613a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Direct, transition metal-free B(dan)-installation into organic frameworks has been developed. Heteroaryl-H bonds were transformable into the respective heteroaryl-B(dan) bonds through deprotonation. The resulting heteroaryl-B(dan) compounds, which are otherwise difficult to access, can undergo the direct Suzuki-Miyaura coupling. The method was demonstrated to apply to a silicon nucleophile, giving Lewis acidity-diminished stable silyl-B(dan) and -B(aam) in one pot.
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Affiliation(s)
- Kazuki Tomota
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
| | - Yuki Izumi
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
| | - Kazuki Nakanishi
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
| | - Masaaki Nakamoto
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
| | - Hiroto Yoshida
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
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