How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions
The recent proliferation of structural studies of organolithium reagents has led to an extended knowledge of the aggregation state of these pervasive synthetic intermediates. Nevertheless, detailed investigations of organolithium reaction mechanisms are still very limited. The most popular technique...
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2002
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08943230_v15_n12_p903_Nudelman http://hdl.handle.net/20.500.12110/paper_08943230_v15_n12_p903_Nudelman |
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paper:paper_08943230_v15_n12_p903_Nudelman2023-06-08T15:47:42Z How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions Anionic cyclization Ate complex Halogen-lithium exchange Li/oxygen carbenoid Lithium surface reactions Organolithium Agglomeration Decay (organic) Lithium Nuclear magnetic resonance Paramagnetic resonance Stereochemistry Ultraviolet spectroscopy Synthetic intermediates Chemical reactions The recent proliferation of structural studies of organolithium reagents has led to an extended knowledge of the aggregation state of these pervasive synthetic intermediates. Nevertheless, detailed investigations of organolithium reaction mechanisms are still very limited. The most popular techniques in the relatively few reported studies are UV, EPR and NMR spectroscopy, the use of radical clocks and investigation of the stereochemical course of the reaction when applied. This paper describes how the search for minor products can be an additional mechanistic tool. Metal-halogen exchange was studied with a new suitable fast radical clock bearing a phenyl group at the alkene C-terminus, even when the probe was able to trap very short-lived radical intermediates, the results showed that the reaction proceeds through an open lithiated intermediate. In another study, radicals of benzil were generated on the lithium surface and their reactions studied in THF. Characterization of the minor products, the rates of decay of the reagent and formation of products, and also periodical EPR of the reaction mixture, allowed the proposal of the whole reaction mechanism. In both reactions studied, the detailed understanding of the reaction mechanisms based on the side-products provided new more economical and environmentally friendly alternatives for the synthesis of substituted 2,3-dihydrobenzo[b]furans and aromatic esters. Copyright © 2002 John Wiley & Sons, Ltd. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08943230_v15_n12_p903_Nudelman http://hdl.handle.net/20.500.12110/paper_08943230_v15_n12_p903_Nudelman |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Anionic cyclization Ate complex Halogen-lithium exchange Li/oxygen carbenoid Lithium surface reactions Organolithium Agglomeration Decay (organic) Lithium Nuclear magnetic resonance Paramagnetic resonance Stereochemistry Ultraviolet spectroscopy Synthetic intermediates Chemical reactions |
| spellingShingle |
Anionic cyclization Ate complex Halogen-lithium exchange Li/oxygen carbenoid Lithium surface reactions Organolithium Agglomeration Decay (organic) Lithium Nuclear magnetic resonance Paramagnetic resonance Stereochemistry Ultraviolet spectroscopy Synthetic intermediates Chemical reactions How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| topic_facet |
Anionic cyclization Ate complex Halogen-lithium exchange Li/oxygen carbenoid Lithium surface reactions Organolithium Agglomeration Decay (organic) Lithium Nuclear magnetic resonance Paramagnetic resonance Stereochemistry Ultraviolet spectroscopy Synthetic intermediates Chemical reactions |
| description |
The recent proliferation of structural studies of organolithium reagents has led to an extended knowledge of the aggregation state of these pervasive synthetic intermediates. Nevertheless, detailed investigations of organolithium reaction mechanisms are still very limited. The most popular techniques in the relatively few reported studies are UV, EPR and NMR spectroscopy, the use of radical clocks and investigation of the stereochemical course of the reaction when applied. This paper describes how the search for minor products can be an additional mechanistic tool. Metal-halogen exchange was studied with a new suitable fast radical clock bearing a phenyl group at the alkene C-terminus, even when the probe was able to trap very short-lived radical intermediates, the results showed that the reaction proceeds through an open lithiated intermediate. In another study, radicals of benzil were generated on the lithium surface and their reactions studied in THF. Characterization of the minor products, the rates of decay of the reagent and formation of products, and also periodical EPR of the reaction mixture, allowed the proposal of the whole reaction mechanism. In both reactions studied, the detailed understanding of the reaction mechanisms based on the side-products provided new more economical and environmentally friendly alternatives for the synthesis of substituted 2,3-dihydrobenzo[b]furans and aromatic esters. Copyright © 2002 John Wiley & Sons, Ltd. |
| title |
How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| title_short |
How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| title_full |
How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| title_fullStr |
How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| title_full_unstemmed |
How the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| title_sort |
how the by-products hint at mechanisms and suggest new synthetic routes in some organolithium reactions |
| publishDate |
2002 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08943230_v15_n12_p903_Nudelman http://hdl.handle.net/20.500.12110/paper_08943230_v15_n12_p903_Nudelman |
| _version_ |
1768542463901827072 |