Radical Arene Addition vs Radical Reduction: Why Organometal Hydride Chain Reactions Stop and How To Make Them Go
| Autor: | Vincent W. Bowry, Chryssostomos Chatgilialoglu |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
education.field_of_study
Addition reaction 010405 organic chemistry Chemistry Radical Organic Chemistry Population Aromatization Tributyltin hydride Electrophilic aromatic substitution 010402 general chemistry 01 natural sciences Medicinal chemistry 0104 chemical sciences Homolysis chemistry.chemical_compound Reagent education |
| Zdroj: | The Journal of Organic Chemistry. 83:10037-10050 |
| ISSN: | 1520-6904 0022-3263 |
| Popis: | Nonideal kinetic chain analysis was used to examine the kinetic limitations of free-radical synthesis. Homolytic aromatic substitution (HAS: ArH + R• → ArR + H•) occurs in a chain-terminating side reaction to the tributyltin hydride ( SnH) reduction chain (RX + SnH + ( i•)cat. → RH + SnX). Kinetic modeling of premixed and slow reagent addition reactions have clarified the mechanisms of SM HAS, with the azo initiator ( iNN i) acting not only as radical source but also (as an H• acceptor) as the redox catalyst for aromatization, and/or as a postaddition oxidant. Refractory halides and other hitherto baffling anomalies may arise from the build up of ipso (rather than ortho)-cycloadduct radicals in the steady-state radical population. The implications of these findings for "tin-free" radical chains (and emerging photoredox methods) are considered via historical and recent examples of the effects of chain-degrading radical transfer (to substrate, product, solvent, initiator, and/or reagent ligands) on the reagent's chain. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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