Issue 29, 2023

Terminal methylene phosphonium ions: precursors for transient monosubstituted phosphinocarbenes

Abstract

Isolable singlet carbenes are among the most important tools in chemistry, but generally require the interaction of two substituents with the electron deficient carbon atom. We herein report a synthetic approach to monosubstituted phosphinocarbenes via deprotonation of hitherto unknown diprotic terminal methylene phosphonium ions. Two methylene phosphonium salts bearing bulky N-heterocyclic imine substituents at the phosphorus atom were isolated and fully characterized. Deprotonation studies indicate the formation of transient monosubstituted carbenes that undergo intermolecular cycloadditions or intramolecular Buchner ring expansion to afford a cycloheptatriene derivative. The reaction mechanism of the latter transformation was elucidated using DFT calculations, which reveal the ambiphilic nature of the phosphinocarbene enabling the insertion into the aromatic C–C bond. Additional computational studies on the role of substituent effects are presented.

Graphical abstract: Terminal methylene phosphonium ions: precursors for transient monosubstituted phosphinocarbenes

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Article information

Article type
Edge Article
Submitted
06 jun 2023
Accepted
29 jun 2023
First published
29 jun 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 7928-7935

Terminal methylene phosphonium ions: precursors for transient monosubstituted phosphinocarbenes

P. Löwe, M. A. Wünsche, F. R. S. Purtscher, J. Gamper, T. S. Hofer, L. F. B. Wilm, M. B. Röthel and F. Dielmann, Chem. Sci., 2023, 14, 7928 DOI: 10.1039/D3SC02899B

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