Reference : Probing the Diastereoselectivity of Staudinger Reactions Catalyzed by N-Heterocyclic ...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
http://hdl.handle.net/2268/184374
Probing the Diastereoselectivity of Staudinger Reactions Catalyzed by N-Heterocyclic Carbenes
English
Hans, Morgan mailto [Université de Liège > Département de chimie (sciences) > Chimie macromoléculaire et catalyse organique >]
Wouters, Johan [Department of Chemistry, Université de Namur, 61 Rue de Bruxelles, Namur, Belgium]
Demonceau, Albert mailto [Université de Liège > Département de chimie (sciences) > Chimie macromoléculaire et catalyse organique >]
Delaude, Lionel mailto [Université de Liège > Département de chimie (sciences) > Chimie organométallique et catalyse homogène >]
2015
Chemistry: A European Journal
Wiley-VCH
21
30
10870-10877
Yes (verified by ORBi)
International
0947-6539
1521-3765
Weinheim
Germany
[en] Catalysis ; Chemical reactions ; Crystallography ; Molecular structure ; Nitrogen compounds ; Olefins ; Organic compounds ; Stereoselectivity ; Thermogravimetric analysis ; Carbenes ; Organocatalysis ; Reaction mechanism ; X ray crystallography
[en] The reaction of ethylphenylketene with 1,3-dimesitylimidazol-2-ylidene (IMes) or 1,3-dimesitylimidazolin-2-ylidene (SIMes) afforded the corresponding azolium enolates in high yields. The two zwitterions were fully characterized by various analytical techniques. Their thermal stabilities were monitored by thermogravimetric analysis and the molecular structure of SIMes.EtPhC=C=O was determined by means of X-ray crystallography. A mechanism was proposed to account for the trans-diastereoselectivity observed in the [2+2] cycloaddition of ketenes and N-protected imines catalyzed by N-heterocyclic carbenes and an extensive catalytic screening was performed to test its validity. The steric bulk of the NHC catalyst markedly affected the cis/trans ratio of the model β-lactam product. The nature of the solvent used to carry out the Staudinger reaction also significantly influenced its diastereoselectivity. Conversely, the nature of the substituent on the N-sulfonated imine reagent and the reaction temperature were less critical parameters.
Researchers ; Professionals
http://hdl.handle.net/2268/184374
10.1002/chem.201501060

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