Journal ArticleDOI
Chiral phosphine lewis bases catalyzed asymmetric aza-Baylis-Hillman reaction of N-sulfonated imines with activated olefins.
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TLDR
An effective bifunctional Lewis base and Bronsted acid phosphine Lewis base system has been disclosed in this catalytic, asymmetric aza-Baylis-Hillman reaction and the mechanistic insight has been investigated by 31P and 1H NMR spectroscopic measurements.Abstract:
In the aza-Baylis-Hillman reaction of N-sulfonated imines (N-arylmethylidene-4-methylbenzenesulfonamides and others) with methyl vinyl ketone, ethyl vinyl ketone, and acrolein, we found that, in the presence of a catalytic amount of chiral phosphine Lewis base such as (R)-2'-diphenylphosphanyl-[1,1']binaphthalenyl-2-ol LB1 (10 mol %) and molecular sieve 4A, the corresponding aza-Baylis-Hillman adducts could be obtained in good yields with good to high ee (70-95% ee) at low temperature (approximately -30 to -20 degrees C) or at room temperature in THF, respectively. In CH2Cl2 upon heating at 40 degrees C, the aza-Baylis-Hillman reaction of N-sulfonated imines with phenyl acrylate or naphthyl acrylate gave the adducts in good to high yields (60-97%) with moderate ee (52-77%). The mechanistic insight has been investigated by 31P and 1H NMR spectroscopic measurements. The key enolate intermediate, which has been stabilized by intramolecular hydrogen bonding, has been observed by 31P and 1H NMR spectroscopy. An effective bifunctional Lewis base and Bronsted acid phosphine Lewis base system has been disclosed in this catalytic, asymmetric aza-Baylis-Hillman reaction.read more
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Journal ArticleDOI
Trifunctional organocatalyst-promoted counterion catalysis for fast and enantioselective aza-Morita–Baylis–Hillman reactions at ambient temperature
Jean-Marc Garnier,Fei Liu +1 more
TL;DR: Fast and enantioselective aza-Morita-Baylis-Hillman reactions between electron-deficient or electron-rich aromatic N-tosyl imines and methyl vinyl ketone were achieved at ambient temperature using asymmetric counterion-directed catalysis promoted by trifunctional organocatalysts with a Brønsted base as the activity switch after protonation with benzoic acid.
Journal ArticleDOI
Phosphine-catalyzed annulations of 4,4-dicyano-2-methylenebut-3-enoates with maleimides and maleic anhydride.
TL;DR: A novel phosphine-catalyzed [4+1] annulation of maleimides with 4,4-dicyano-2-methylenebut-3-enoates with stable phosphinium-containing zwitterionic compound has been developed to afford spirocyclic products, and the femaleimides serves as C1 synthons.
Journal ArticleDOI
Aza-Baylis–Hillman reaction of N-tosylated imines with β-substituted α,β-unsaturated esters
Yong-Ling Shi,Min Shi +1 more
TL;DR: Aza-Baylis-Hillman reaction of N-tosylated imines with beta-substituted alpha,beta-unsaturated esters can take place under mild reaction conditions to give the corresponding Baylis- Hillman adducts in moderate to excellent Yields.
Journal ArticleDOI
Asymmetric transfer hydrogenation of aromatic ketones with the ruthenium(II) catalyst derived from C2 symmetric N,N'-bis[(1S)-1-benzyl-2-O-(diphenylphosphinite)ethyl]ethanediamide
TL;DR: In this article, a chiral phosphinite compound N,N′ -bis[(1 S )-1-benzyl-2- O -(diphenylphosphinite)ethyl]ethanediamide (1 ), has been synthesized by the reaction of chlorodiphenymethylphosphine with N, N′ −bis[ (1 S)- 1-bensyl 2-hydroxyethyl]ETHanediamides under argon atmosphere, and the new complexes were characterized by using NMR, FT-IR spectroscop
Journal ArticleDOI
The First Air‐Stable and Efficient Nucleophilic Trialkylphosphine Organocatalyst for the Baylis–Hillman Reaction
TL;DR: Under the mediation of 15–20 mol % of PTA and practical conditions, both aromatic and aliphatic aldehydes react with the activated alkenes like acrylates and methyl vinyl ketone to afford the corresponding adducts in fair to excellent yields.
References
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[(salen)Al]-Mediated, Controlled and Stereoselective Ring-Opening Polymerization of Lactide in Solution and without Solvent: Synthesis of Highly Isotactic Polylactide Stereocopolymers from Racemic d,l-Lactide
TL;DR: Easily accessible [(salen)(iPrO)Al] exerts excellent molecular-weight and stereochemical control in lactide polymerization either in solution or in the absence of solvent.
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Chiral Amine-Catalyzed Asymmetric Baylis−Hillman Reaction: A Reliable Route to Highly Enantiomerically Enriched (α-Methylene-β-hydroxy)esters
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Asymmetric Morita-Baylis-Hillman reactions catalyzed by chiral Brønsted acids.
TL;DR: The Brønsted-acid-catalyzed reaction is the first example of a highly enantioselective asymmetric MBH reaction of cyclohexenone with aldehydes.
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Development of bis-thiourea-type organocatalyst for asymmetric Baylis–Hillman reaction
TL;DR: A chiral bis-thiourea-type organocatalyst 2 developed for the Baylis-Hillman reaction provided a drastic rate enhancement in the case of cyclohexanecarboxaldehyde as discussed by the authors.
Journal ArticleDOI
β-Isocupreidine-Catalyzed Asymmetric Baylis−Hillman Reaction of Imines
TL;DR: A mechanistic proposal governed by hydrogen bonding is presented to give (S)-enriched N-protected-alpha-methylene-beta-amino acid esters, which shows the opposite enantioselectivity to the corresponding aldehydes.