Reactivities of allenic and olefinic Michael acceptors towards phosphines

An, Feng; Jangra, Harish; Wei, Yin; Shi, Min; Zipse, Hendrik; Ofial, Armin R.

doi:10.1039/d1cc06786a

Cited by 10 publications

(5 citation statements)

References 37 publications

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“…To describe quantitatively the reactivity of electrophiles and nucleophiles, Mayr and co-workers proposed a three-parameter eq based on the electrophilicity E , solvent-dependent nucleophilicity N , and susceptibility s N : …”

Section: Resultsmentioning

confidence: 99%

Stereoelectronic Effect in the Reaction of α-Methylene Lactones with Tertiary Phosphines and Its Application in Organocatalysis

et al. 2023

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The kinetic data indicate that the addition of tertiary phosphines to α-methylene lactones in acetic acid is strongly accelerated in comparison to the reactions of related open-chain esters. Six-membered α-methylene-δ-valerolactone exhibited a more pronounced rate increase than five-membered α-methylene-γ-butyrolactone. The use of α-methylene-γ-butyrolactam as a nitrogen analogue of α-methylene-γ-butyrolactone resulted in a total loss of the reaction acceleration. The observed reactivities were rationalized by DFT calculations at the RwB97XD/6-31+G(d,p) level of theory, showing that the intramolecular interaction between phosphonium and enolate oxygen centers provided by the locked s-cis-geometry of the heterocycles plays an important role in the stabilization of intermediate zwitterions. The reactivity is also controlled by the conformational flexibility of the heterocycle. The geometries of five-membered and, especially, six-membered lactone cycles are slightly changed upon the nucleophilic attack of phosphine, leading to the stabilizing stereoelectronic effect by the Ρ···Ο interaction. The addition of phosphine to α-methylene-γ-butyrolactam significantly distorts the initial geometry of the heterocycle, making the nucleophilic attack unfavorable. The application of the stereoelectronic effect to enhance the efficiency of the phosphine-catalyzed Michael and Pudovik reactions of α-methylene lactones was demonstrated.

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Section: Resultsmentioning

confidence: 99%

Stereoelectronic Effect in the Reaction of α-Methylene Lactones with Tertiary Phosphines and Its Application in Organocatalysis

et al. 2023

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“…11 In ongoing attempts to expand the use of compounds 1 to access novel chemical space by targeting highly functionalized enantioenriched heterocycles 2 via asymmetric -functionalization reactions, we now became interested in using allenoates 3 as possible C sp -electrophiles (undergoing -addition). [15][16][17][18][19] Interestingly, the acceptor properties of allenoates 3 can be tuned by nature of the catalyst system. 15 While the use of (chiral) phosphine catalysts usually allows for -additions, it has also been reported that the use of simple inorganic Brønsted bases, 17 chiral organobases, 19 or the use of chiral quaternary ammonium salt catalysts under classical phasetransfer conditions 18 allow for -selective additions of Cnucleophiles (i.e., in situ generated enolate species) with promising enantioselectivities.…”

Section: Paper Synthesismentioning

confidence: 99%

Enantioselective β-Selective Addition of Isoxazolidin-5-ones to Allenoates Catalyzed by Quaternary Ammonium Salts

et al. 2022

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“…15 Lu and co-workers have used a catalytic amount of tertiary phosphine to undertake [3+2] cycloadditions of allene substrates, forming cyclopentene products. 16 More recently, this transformation has been studied in detail by Ofial and coworkers, with vinyl phosphonium intermediates being trapped to allow characterization of the phosphine addition products, 17 whose chemoselectivity is similar to that obtained from a hydrophosphination reaction.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Hydrophosphination of Allenes Using an Iron(II) β-Diketiminate Complex

Woof¹,

Linford-Wood²,

Mahon³

et al. 2022

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A rare study into the catalytic hydrophosphination of allenes is reported. Employing an Fe(II) ß-diketiminate pre-catalyst, the reaction of HPPh2 proceeds with a range of aryl- and alkyl allenes. For arylallenes the E-vinyl product formed as the major species, while the 1,1-disubstituted alkene is formed in a larger ratio than the Z-vinyl product (e.g. 6 : 3 : 1 as E : 1,1 : Z). Use of H2PPh results in good yields of the 1,1-disubstituted alkene, where the resultant secondary phosphine product does not undergo further reaction. We postulate a catalytic cycle based on spectroscopic data. Employing an [Fe(salen)]2-μ-oxo pre-catalyst leads to phosphine dehydrocoupling rather than hydrophosphination.

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Reactivities of allenic and olefinic Michael acceptors towards phosphines

Abstract: Insights into the first step of R3P-catalysed Lu cycloadditions are given by the kinetics of phosphine additions to alkyl allenoates.

Cited by 10 publications

References 37 publications

Stereoelectronic Effect in the Reaction of α-Methylene Lactones with Tertiary Phosphines and Its Application in Organocatalysis

Stereoelectronic Effect in the Reaction of α-Methylene Lactones with Tertiary Phosphines and Its Application in Organocatalysis

Enantioselective β-Selective Addition of Isoxazolidin-5-ones to Allenoates Catalyzed by Quaternary Ammonium Salts

Catalytic Hydrophosphination of Allenes Using an Iron(II) β-Diketiminate Complex

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