Abstract
α-Diimines are commonly used as supporting ligands for a variety of transition metal-catalyzed processes, most notably in α-olefin polymerization. They are also precursors to valuable synthetic targets, such as chiral 1,2-diamines. Their synthesis is usually performed through acid-catalyzed condensation of amines with α-diketones. Despite the simplicity of this approach, accessing unsymmetrical α-diimines is challenging. Herein, we report the Ti-mediated intermolecular diimination of alkynes to afford a variety of symmetrical and unsymmetrical α-diimines through the reaction of diazatitanacyclohexadiene intermediates with C-nitrosos. These diazatitanacycles can be readily accessed in situ via the multicomponent coupling of TiNR imidos with alkynes and nitriles. The formation of α-diimines is achieved through formal [4 + 2]-cycloaddition of the C-nitroso to the Ti and γ-carbon of the diazatitanacyclohexadiene followed by two subsequent cycloreversion steps to eliminate nitrile and afford the α-diimine and a Ti oxo.
Original language | English (US) |
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Pages (from-to) | 1469-1477 |
Number of pages | 9 |
Journal | Chemical Science |
Volume | 13 |
Issue number | 5 |
DOIs | |
State | Published - Feb 7 2022 |
Bibliographical note
Funding Information:Financial support was provided by the National Institutes of Health (R35GM119457), and the Alfred P. Sloan Foundation (I. A. T. is a 2017 Sloan Fellow). D. T. E. kindly acknowledges nancial support by the ETH Zurich foundation (D. T. E. is a 2019 ESOP scholar). Y. C. acknowledges funding support from the Wayland E. Noland Fellowship (UMN). Instrumentation for the University of Minnesota Chemistry NMR facility was supported from a grant through the National Institutes of Health (S10OD011952). X-ray diffraction experiments were performed with a diffractometer purchased through a grant from NSF/MRI (1229400) and the University of Minnesota. Dr Evan Beaumier, Dr Robin Harkins, and Dr Xuelan Wen are acknowledged for helpful discussions. The Minnesota Supercomputing Institute (MSI) at the University of Minnesota for provided resources that contributed to the results reported within this paper.
Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PubMed: MeSH publication types
- Journal Article