Back to Search Start Over

Influence of N-Substitution on the Formation and Oxidation of NHC–CAAC-Derived Triazaalkenes

Authors :
Biprajit Sarkar
Ravi Kumar
Ramapada Dolai
Simon Suhr
Debdeep Mandal
Nicolas Chrysochos
Ramakirushnan Suriya Narayanan
Pankaj Kalita
Anukul Jana
Carola Schulzke
Gopalan Rajaraman
Vadapalli Chandrasekhar
Source :
The Journal of Organic Chemistry. 84:8899-8909
Publication Year :
2019
Publisher :
American Chemical Society (ACS), 2019.

Abstract

We have studied the effect of N-substitution on the course of the reaction of imidazolium triflate. The reaction of N-heterocyclic carbene with N-tBu-substituted pyrrolinium triflate afforded 2-(pyrrolidin-2-yl)-imidazolium triflate, 3R. Treatment of 3R with potassium bis(trimethylsilyl)amide (KHMDS) leads to either the dealkylation product 4 or the deprotonation product, triazaalkene 5, depending on the N-substitution at the imidazolium moiety. Density functional studies using the B3LYP/TZVP setup have been employed to explore various pathways for the dealkylation reaction and the calculated energies support the dealkylation by a large energy margin compared to the deprotonatation process. Theoretical calculations revealed that dealkylation reaction is thermodynamically more favorable than deprotonation. The triazaalkene 5 could be oxidized by AgOTf to the corresponding radical cation 6 and dication 7 in-situ. While 6 and 7 could not be isolated, the formation of the former is inferred by electron paramagnetic resonance spectroscopy and its abstraction of a H-atom to afford 3Me. Similarly, the formation of the dication 7 is inferred by its ready elimination of isobutylene affording 8.

Details

ISSN :
15206904 and 00223263
Volume :
84
Database :
OpenAIRE
Journal :
The Journal of Organic Chemistry
Accession number :
edsair.doi...........26d0367cf1199607d420e9c2c3c345b7
Full Text :
https://doi.org/10.1021/acs.joc.9b00774