| Full text | |
| Author(s): |
Kawamura, Meire Y.
;
Alegre-Requena, Juan, V
;
Barbosa, Thais M.
;
Tormena, Claudio F.
;
Paton, Robert S.
;
Ferreira, Marco A. B.
Total Authors: 6
|
| Document type: | Journal article |
| Source: | CHEMISTRY-A EUROPEAN JOURNAL; v. 28, n. 69, p. 9-pg., 2022-10-19. |
| Abstract | |
[3+2] cycloadditions of nitroolefins have emerged as a selective and catalyst-free alternative for the synthesis of 1,2,3-triazoles from azides. We describe mechanistic studies into the cycloaddition/rearomatization reaction sequence. DFT calculations revealed a rate-limiting cycloaddition step proceeding via an asynchronous TS with high kinetic selectivity for the 1,5-triazole. Kinetic studies reveal a second-order rate law, and C-13 kinetic isotopic effects at natural abundance were measured with a significant normal effect at the conjugated olefinic centers of 1.0158 and 1.0216 at the alpha and beta-carbons of beta-nitrostyrene. Distortion/interaction-activation strain and energy decomposition analyses revealed that the major regioisomeric pathway benefits from an earlier and less-distorted TS, while intermolecular interaction terms dominate the preference for 1,5- over 1,4-cycloadducts. In addition, the major regioisomer also has more favorable electrostatic and dispersion terms. Additionally, while static DFT calculations suggest a concerted but highly asynchronous Ei-type HNO2 elimination mechanism, quasiclassical direct-dynamics calculations reveal the existence of a dynamic intermediate. (AU) | |
| FAPESP's process: | 17/01754-0 - Experimental and theoretical studies on cycloaddition (3 + 2) reactions of azides to nitro-olefins |
| Grantee: | Meire Yasuko Kawamura |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 20/10246-0 - Nuclear magnetic resonance spectroscopy: from pulse sequences to structural assignments |
| Grantee: | Claudio Francisco Tormena |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 20/01255-6 - Application of statistical tools in catalysis for understanding and predicting organic reactions |
| Grantee: | Marco Antonio Barbosa Ferreira |
| Support Opportunities: | Regular Research Grants |