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Disclosure of some obscure mechanistic aspects of the copper-catalyzed click reactions involving N2 elimination promoted by the use of electron-deficient azides from a DFT perspective
Citation
Roohzadeh, R and Nasiri, B and Chipman, A and Yates, BF and Ariafard, A, Disclosure of some obscure mechanistic aspects of the copper-catalyzed click reactions involving N2 elimination promoted by the use of electron-deficient azides from a DFT perspective, Organometallics, 38, (2) pp. 256-267. ISSN 0276-7333 (2019) [Refereed Article]
Copyright Statement
© 2018 American Chemical Society
DOI: doi:10.1021/acs.organomet.8b00691
Abstract
We have used density functional theory to explore the copper(I)-catalyzed reaction between a mesyl azide and a terminal alkyne that leads to a ketenimine whose interaction with nucleophilic water produces an amide. It is well reported in the literature that a cuprated triazole intermediate is formed during the course of such a catalytic cycle. In this contribution, we investigated the stability of this key intermediate by varying the R substituent on the azide and found that electron-withdrawing R substituents make this intermediate more reactive toward ring opening/N2 elimination; an electron-withdrawing R substituent facilitates this process by weakening the N–N bond being cleaved. We also rationalized why the cycloaddition step in this class of click reactions is required to proceed via a binuclear mechanism. The copper(I) acetylide intermediate formed during the catalysis gains extra stability upon scavenging a second Cu complex, resulting in the cycloaddition step occurring with a lower activation barrier. We also noticed that, similar to the ring closure step, inclusion of a second Cu complex may accelerate the ring opening/N2 elimination process. It was shown that the ketenimine needs to coordinate to a copper center via its nitrogen atom in order to be activated toward hydrolysis.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | density functional theory, activation energy, click reactions, electron-deficient azides |
| Research Division: | Chemical Sciences |
| Research Group: | Organic Chemistry |
| Research Field: | Physical Organic Chemistry |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding Knowledge |
| Objective Field: | Expanding Knowledge in the Chemical Sciences |
| UTAS Author: | Chipman, A (Mr Antony Chipman) |
| UTAS Author: | Yates, BF (Professor Brian Yates) |
| UTAS Author: | Ariafard, A (Associate Professor Alireza Ariafard) |
| ID Code: | 134447 |
| Year Published: | 2019 |
| Funding Support: | Australian Research Council (DP180100904) |
| Web of Science® Times Cited: | 1 |
| Deposited By: | Chemistry |
| Deposited On: | 2019-08-13 |
| Last Modified: | 2019-12-09 |
| Downloads: | 0 |
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