Amine-Catalyzed Phospha-Michael Reaction of α,β-Unsaturated Aldehydes and Ketones with Multifunctional N-Heterocyclic Phosphine-Thioureas as Phosphonylation Reagent

2016 ◽  
Vol 18 (17) ◽  
pp. 4372-4375 ◽  
Author(s):  
Hai Huang ◽  
Jun Yong Kang
Keyword(s):  
Michael Reaction ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones

scholarly journals Evidence for an enolate mechanism in the asymmetric Michael reaction of α,β-unsaturated aldehydes and ketones via a hybrid system of two secondary amine catalysts

2020 ◽  
Vol 11 (41) ◽  
pp. 11293-11297 ◽  
Author(s):  
Nariyoshi Umekubo ◽  
Takahiro Terunuma ◽  
Eunsang Kwon ◽  
Yujiro Hayashi
Keyword(s):  
Hybrid System ◽  
Secondary Amine ◽  
Michael Reaction ◽  
Silyl Ether ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Asymmetric Michael Reaction ◽  
Amine Catalysts

The key nucleophile was found to be neither an enamine nor an enol, but an enolate in the direct Michael reaction of α,β-unsaturated aldehydes and non-activated ketones catalyzed by two amine catalysts namely diphenylprolinol silyl ether and pyrrolidine.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

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