A potential role of substrate as a base for deprotonation pathway in Rh-catalysed C-H amination of heteroArenes: DFT insights
Type
ArticleKAUST Department
Chemical Science ProgramHomogeneous Catalysis Laboratory (HCL)
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Date
2016Permanent link to this record
http://hdl.handle.net/10754/604353
Metadata
Show full item recordAbstract
The possibility of direct introduction of a new functionality through C–H bond activation is an attractive strategy in covalent synthesis. Here, we investigated the mechanism of Rh-catalysed C-H amination of the hetero-aryl substrate (2-phenylpyridine) using phenyl azide as nitrogen source by density functional theory (DFT). For the deprotocyclometallation and protodecyclometallation processes of the title reaction, we propose a stepwise base-assisted mechanism (pathway I) instead of previously reported concerted mechanism (pathway II). In the new mechanism proposed here, 2-phenylpyridine acts as a base in the initial deprotonation step (C-H bond cleavage) and transports the proton towards the final protonation step. In fact, the N-H bond of the strong conjugate acid (formed during initial C-H bond cleavage) considered in pathway I (via TS4) is more acidic than the C-H bond of the neutral substrate considered in pathway II (via TS5). The higher activation barrier of TS5 mainly originates from the ring strain of the four membered cyclic transition state. The vital role of base, as disclosed here, can potentially have broader mechanistic implications for the development of reaction conditions of transition metal catalysed reactions.Citation
A potential role of substrate as a base for deprotonation pathway in Rh-catalysed C-H amination of heteroArenes: DFT insights 2016 Dalton Trans.Sponsors
This work was supported by the National Research Foundation of Korea Grant (NRF-2015R1A2A1A15055539) funded by Korean Government. The generous support from computation facilities at the KAUST IT and Supercomputing Lab as well as KISTI is also acknowledged.Publisher
Royal Society of Chemistry (RSC)Journal
Dalton Trans.PubMed ID
27071025Additional Links
http://pubs.rsc.org/en/Content/ArticleLanding/2016/DT/C6DT00686Hae974a485f413a2113503eed53cd6c53
10.1039/C6DT00686H
Scopus Count
Related articles
- Transition-metal-catalyzed C-N bond forming reactions using organic azides as the nitrogen source: a journey for the mild and versatile C-H amination.
- Authors: Shin K, Kim H, Chang S
- Issue date: 2015 Apr 21
- Mechanistic studies of the rhodium-catalyzed direct C-H amination reaction using azides as the nitrogen source.
- Authors: Park SH, Kwak J, Shin K, Ryu J, Park Y, Chang S
- Issue date: 2014 Feb 12
- Computational mechanistic elucidation of the intramolecular aminoalkene hydroamination catalysed by iminoanilide alkaline-earth compounds.
- Authors: Tobisch S
- Issue date: 2015 Apr 27
- The Mechanism of N-O Bond Cleavage in Rhodium-Catalyzed C-H Bond Functionalization of Quinoline N-oxides with Alkynes: A Computational Study.
- Authors: Li Y, Liu S, Qi Z, Qi X, Li X, Lan Y
- Issue date: 2015 Jul 6
- The mechanism of catalytic methylation of 2-phenylpyridine using di-tert-butyl peroxide.
- Authors: Sharma AK, Roy D, Sunoj RB
- Issue date: 2014 Jul 14