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Literature DB >> 31589054

Hyperconjugative Antiaromaticity Activates 4H-Pyrazoles as Inverse-Electron-Demand Diels-Alder Dienes.

Brian J Levandowski^1,2, Nile S Abularrage¹, K N Houk², Ronald T Raines¹.

Abstract

The Diels-Alder reactivity of 4,4-difluoro-3,5-diphenyl-4H-pyrazole was investigated experimentally and computationally with endo-bicyclo[6.1.0]non-4-yne. The computationally predicted rate enhancement from hyperconjugative antiaromaticity induced by fluorination of cyclopentadienes at the 5-position extends to five-membered heterocyclic dienes containing a saturated center. 4,4-Difluoro-4H-pyrazoles are new electron-deficient dienes with rapid reactivities toward strained alkynes.

Entities: Chemical Disease Gene Mutation Species

Year: 2019 PMID： 31589054 PMCID： PMC7015664 DOI： 10.1021/acs.orglett.9b03351

Source DB: PubMed Journal: Org Lett ISSN： 1523-7052 Impact factor: 6.005

13 in total

1. Nucleus-independent chemical shifts (NICS) as an aromaticity criterion.

Authors: Zhongfang Chen; Chaitanya S Wannere; Clémence Corminboeuf; Ralph Puchta; Paul von Ragué Schleyer
Journal: Chem Rev Date: 2005-10 Impact factor: 60.622

2. Which NICS aromaticity index for planar pi rings is best?

Authors: Hossein Fallah-Bagher-Shaidaei; Chaitanya S Wannere; Clémence Corminboeuf; Ralph Puchta; Paul v R Schleyer
Journal: Org Lett Date: 2006-03-02 Impact factor: 6.005

3. Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions.

Authors: Aleksandr V Marenich; Christopher J Cramer; Donald G Truhlar
Journal: J Phys Chem B Date: 2009-05-07 Impact factor: 2.991

4. Magnetic criteria of aromaticity.

Authors: Renana Gershoni-Poranne; Amnon Stanger
Journal: Chem Soc Rev Date: 2015-06-02 Impact factor: 54.564

5. Theoretical analysis of reactivity patterns in Diels-Alder reactions of cyclopentadiene, cyclohexadiene, and cycloheptadiene with symmetrical and unsymmetrical dienophiles.

Authors: Brian J Levandowski; K N Houk
Journal: J Org Chem Date: 2015-03-19 Impact factor: 4.354

6. Clicking 1,2,4,5-tetrazine and cyclooctynes with tunable reaction rates.

Authors: Weixuan Chen; Danzhu Wang; Chaofeng Dai; Donald Hamelberg; Binghe Wang
Journal: Chem Commun (Camb) Date: 2011-12-12 Impact factor: 6.222

7. Diels-Alder Reactivities of Benzene, Pyridine, and Di-, Tri-, and Tetrazines: The Roles of Geometrical Distortions and Orbital Interactions.

Authors: Yun-Fang Yang; Yong Liang; Fang Liu; K N Houk
Journal: J Am Chem Soc Date: 2016-02-02 Impact factor: 15.419

Hyperconjugative Antiaromaticity Activates 4H-Pyrazoles as Inverse-Electron-Demand Diels-Alder Dienes.

1. Nucleus-independent chemical shifts (NICS) as an aromaticity criterion.

2. Which NICS aromaticity index for planar pi rings is best?

3. Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions.

4. Magnetic criteria of aromaticity.

5. Theoretical analysis of reactivity patterns in Diels-Alder reactions of cyclopentadiene, cyclohexadiene, and cycloheptadiene with symmetrical and unsymmetrical dienophiles.

6. Clicking 1,2,4,5-tetrazine and cyclooctynes with tunable reaction rates.

7. Diels-Alder Reactivities of Benzene, Pyridine, and Di-, Tri-, and Tetrazines: The Roles of Geometrical Distortions and Orbital Interactions.

8. Schleyer hyperconjugative aromaticity and Diels-Alder reactivity of 5-substituted cyclopentadienes.

9. Substituent effects on "hyperconjugative" aromaticity and antiaromaticity in planar cyclopolyenes.

10. Readily Accessible Ambiphilic Cyclopentadienes for Bioorthogonal Labeling.

1. Differential Effects of Nitrogen Substitution in 5- and 6-Membered Aromatic Motifs.

2. Developing bioorthogonal probes to span a spectrum of reactivities.

3. Click Chemistry with Cyclopentadiene.

4. Antiaromaticity Gain Activates Tropone and Nonbenzenoid Aromatics as Normal-Electron-Demand Diels-Alder Dienes.

5. Geminal Repulsion Disrupts Diels-Alder Reactions of Geminally Substituted Cyclopentadienes and 4H-Pyrazoles.

6. Synthesis and Diels-Alder Reactivity of 4-Fluoro-4-Methyl-4H-Pyrazoles.