The aza-Morita–Baylis–Hillman reaction of electronically and sterically deactivated substrates

Lindner, Christoph; Tandon, Raman; Liu, Yinghao; Maryasin, Boris; Zipse, Hendrik

doi:10.1039/c2ob07058h

Cited by 20 publications

(12 citation statements)

References 64 publications

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“…Zwitterionic adducts formed by pyridine 63 are somewhat more stable than those formed by triphenylphosphane ( 89 ). These energetics parallel results obtained in azaMBH reactions of these three substrates with aromatic imines [30]. Matching the affinity data for Michael acceptors with MCA values we also find an inversion of Lewis basicity in that phosphane 89 has a larger MCA value but a lower binding affinity to the prototypical Michael acceptors selected here.…”

Section: Resultssupporting

confidence: 86%

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Cation affinity numbers of Lewis bases

Lindner

Tandon²,

Maryasin³

et al. 2012

Beilstein J. Org. Chem.

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SummaryUsing selected theoretical methods the affinity of a large range of Lewis bases towards model cations has been quantified. The range of model cations includes the methyl cation as the smallest carbon-centered electrophile, the benzhydryl and trityl cations as models for electrophilic substrates encountered in Lewis base-catalyzed synthetic procedures, and the acetyl cation as a substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles.

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Section: Resultssupporting

confidence: 86%

“…It was recently shown that 3,4-diaminopyridines are catalytically active in a variety of group transfer reactions [9–10 30]. Chiral 3,4-diaminopyridines thus have the potential to act as catalysts in stereoselective transformations.…”

Section: Resultsmentioning

confidence: 99%

Cation affinity numbers of Lewis bases

Lindner

Tandon²,

Maryasin³

et al. 2012

Beilstein J. Org. Chem.

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“…[5] Pyridine derivative 3 is a powerful organocatalyst not only suitable for acylation reactions, but also for other transformations such as the aza-Morita-Baylis-Hillman reaction. [6] Further development of this class of catalysts through modification of the attached ring systems thus seems desirable, but faces significant synthetic hurdles. We, therefore, explore here the potential of the respective di-and trinitrogen-substituted systems 4 and 5 ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…A small improvement in catalytic activity was soon after documented for 4‐(pyrrolidinyl)pyridine (PPY; 2 ),4 but it took until 2003 that a larger increase in activity could be realized with annelated pyridines such as 9‐azajulolidine ( 3 ) 5. Pyridine derivative 3 is a powerful organocatalyst not only suitable for acylation reactions, but also for other transformations such as the aza‐Morita–Baylis–Hillman reaction 6. Further development of this class of catalysts through modification of the attached ring systems thus seems desirable, but faces significant synthetic hurdles.…”

Section: Introductionmentioning

confidence: 99%

Annelated Pyridines as Highly Nucleophilic and Lewis Basic Catalysts for Acylation Reactions

Tandon

Unzner

Nigst

et al. 2013

Chemistry A European J

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New heterocyclic derivatives of 9-azajulolidine have been synthesized and characterized with respect to their nucleophilicity and Lewis basicity. The Lewis basicity of these bases as quantified through their theoretically calculated methyl-cation affinities correlate well with the experimentally measured reaction rates for addition to benzhydryl cations. All newly synthesized pyridines show exceptional catalytic activities in benchmark acylation reactions, which correlate only poorly with Lewis basicity or nucleophilicity parameters. A combination of Lewis basicity with charge and geometric parameters in the framework of a three-component quantitative structure-activity relationship (QSAR) model is, however, highly predictive.

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“…In this way, the electron density on phosphorous and thus nucleophilicity is increased. This strategy has for example been exploited in the reaction of ethyl acrylate with 4-nitrobenzaldehyde, 14 in aza Morita-Baylis Hilman reactions, 15 or in umpolung [3+2] annulations. 16 In all these cases, the reactions were performed without protective gas indicating that electronically modified arylphosphines tolerate the presence of oxygen.…”

Section: Introductionmentioning

confidence: 99%

Electron Rich Triarylphosphines as Nucleophilic Catalysts for Oxa-Michael Reactions

Fischer¹,

Renner²,

Boese³

et al. 2021

Preprint

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Herein, we study the activity of methoxysubstituted arylphosphines (4-methoxy-phenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP) in catalyzing oxa-Michael additions in comparison to commonly used triphenylphosphine (TPP). Acrylonitrile, acryl amide and divinyl sulfone are used as Michael acceptors and propargyl alcohol, allyl alcohol, n-propanol and i-propanol are assessed as Michael donors. In many cases, catalyst loadings of only 1 mol% in respect to the Michael acceptor are sufficient to provide full conversion towards the Michael adduct in 24 h at room temperature. Generally, TMTPP is the most active catalyst in all cases. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine – Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was evaluated and electron richest TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut-Currier type repeat units and consequently lower molar masses were obtained.

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The aza-Morita–Baylis–Hillman reaction of electronically and sterically deactivated substrates

Cited by 20 publications

References 64 publications

Cation affinity numbers of Lewis bases

Cation affinity numbers of Lewis bases

Annelated Pyridines as Highly Nucleophilic and Lewis Basic Catalysts for Acylation Reactions

Electron Rich Triarylphosphines as Nucleophilic Catalysts for Oxa-Michael Reactions

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