A redox-active diborane platform performs C(sp3)–H activation and nucleophilic substitution reactions
- Organoboranes are among the most versatile and widely used reagents in synthetic chemistry. A significant further expansion of their application spectrum would be achievable if boron-containing reactive intermediates capable of inserting into C–H bonds or performing nucleophilic substitution reactions were readily available. However, current progress in the field is still hampered by a lack of universal design concepts and mechanistic understanding. Herein we report that the doubly arylene-bridged diborane(6) 1H2 and its B[double bond, length as m-dash]B-bonded formal deprotonation product Li2[1] can activate the particularly inert C(sp3)–H bonds of added H3CLi and H3CCl, respectively. The first case involves the attack of [H3C]− on a Lewis-acidic boron center, whereas the second case follows a polarity-inverted pathway with nucleophilic attack of the B[double bond, length as m-dash]B double bond on H3CCl. Mechanistic details were elucidated by means of deuterium-labeled reagents, a radical clock, α,ω-dihaloalkane substrates, the experimental identification of key intermediates, and quantum-chemical calculations. It turned out that both systems, H3CLi/1H2 and H3CCl/Li2[1], ultimately funnel into the same reaction pathway, which likely proceeds past a borylene-type intermediate and requires the cooperative interaction of both boron atoms.
Author: | Thomas Kaese, Timo TrageserGND, Hendrik Budy, Michael BolteORCiD, Hans-Wolfram LernerORCiDGND, Matthias WagnerORCiD |
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URN: | urn:nbn:de:hebis:30:3-465090 |
DOI: | https://doi.org/10.1039/c8sc00743h |
ISSN: | 2041-6539 |
ISSN: | 2041-6520 |
Pubmed Id: | https://pubmed.ncbi.nlm.nih.gov/29780520 |
Parent Title (English): | Chemical science |
Publisher: | RSC |
Place of publication: | Cambridge |
Document Type: | Article |
Language: | English |
Year of Completion: | 2018 |
Date of first Publication: | 2018/03/19 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2018/05/29 |
Volume: | 9 |
Issue: | 15 |
Page Number: | 11 |
First Page: | 3881 |
Last Page: | 3891 |
Note: | This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. |
HeBIS-PPN: | 433867779 |
Institutes: | Biochemie, Chemie und Pharmazie / Biochemie und Chemie |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
Sammlungen: | Universitätspublikationen |
Licence (German): | Creative Commons - Namensnennung 3.0 |