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- Title
Azomethine Ylides from Nitrones: Using Catalytic nBuLi for the Totally Stereoselective Synthesis of trans-2-Alkyl-3-oxazolines.
- Authors
Juste ‐ Navarro, Veronica; Delso, Ignacio; Tejero, Tomás; Merino, Pedro
- Abstract
The cycloaddition of azomethine ylide N-oxides (nitrone ylides) with aldehydes provides 3-oxazolines in a completely stereoselective manner in the presence of a catalytic amount of n-butyllithium. The process involves an initial nucleophilic attack on the aldehyde, followed by intramolecular oxygen addition to the nitrone moiety and lithium-assisted elimination of water, regenerating the catalytic species. Various Li-based catalytic systems are possible and the in situ generated water is required for continuing the catalytic cycle. The best results are observed with 20 mol % of n-butyllithium, whereas the use of stoichiometric amounts inhibit the rate of catalysis. Experimental, spectroscopic, and computational mechanistic studies have provided evidence of lithium-ion catalysis and rationalized several competing catalytic pathways
- Subjects
RING formation (Chemistry); YLIDES; NUCLEOPHILIC addition (Chemistry); NUCLEOPHILIC catalysis; LITHIUM-ion batteries
- Publication
Chemistry - A European Journal, 2016, Vol 22, Issue 33, p11527
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201602159