Electron Rich Triarylphosphines as Nucleophilic Catalysts for Oxa-Michael Reactions

10.26434/chemrxiv.14241953.v1 ◽

2021 ◽

Author(s):

Susanne Fischer ◽

Simon Renner ◽

Adrian Daniel Böse ◽

Christian Slugovc

Keyword(s):

Room Temperature ◽

Oxidation Stability ◽

Strong Impact ◽

Michael Adduct ◽

Michael Additions ◽

Michael Reactions ◽

Repeat Units ◽

Michael Acceptor ◽

Michael Acceptors ◽

Reaction Speed

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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Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.17.117 ◽

2021 ◽

Vol 17 ◽

pp. 1689-1697

Author(s):

Susanne M Fischer ◽

Simon Renner ◽

A Daniel Boese ◽

Christian Slugovc

Keyword(s):

Room Temperature ◽

Oxidation Stability ◽

Catalyst Loading ◽

Strong Impact ◽

Michael Reactions ◽

Solvent Free Conditions ◽

Michael Acceptor ◽

Test Reactions ◽

Michael Acceptors ◽

The Impact

Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions and at room temperature. The results reveal a decisive superiority of TMTPP for converting poor and intermediate Michael acceptors such as acrylamide and acrylonitrile and for converting less acidic alcohols like isopropanol. With stronger Michael acceptors and more acidic alcohols, the impact of the more electron-rich catalysts is less pronounced. 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 also evaluated and the most electron-rich 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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Enantioselective Michael Addition of Malonates to Enones

Current Organic Chemistry ◽

10.2174/1385272824666200316122221 ◽

2020 ◽

Vol 24 (7) ◽

pp. 746-773

Author(s):

Péter Bakó ◽

Tamás Nemcsok ◽

Zsolt Rapi ◽

György Keglevich

Keyword(s):

Michael Addition ◽

Activity Relationship ◽

Chalcone Derivatives ◽

Michael Additions ◽

Michael Reactions ◽

Structure Activity ◽

Cyclic Enones ◽

Michael Acceptors ◽

Relationship Of ◽

Enantioselective Catalysts

: Many catalysts were tested in asymmetric Michael additions in order to synthesize enantioenriched products. One of the most common reaction types among the Michael reactions is the conjugated addition of malonates to enones making it possible to investigate the structure–activity relationship of the catalysts. The most commonly used Michael acceptors are chalcone, substituted chalcones, chalcone derivatives, cyclic enones, while typical donors may be dimethyl, diethyl, dipropyl, diisopropyl, dibutyl, di-tert-butyl and dibenzyl malonates. This review summarizes the most important enantioselective catalysts applied in these types of reactions.

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Highly Efficient Michael Reactions of Nitroolefins by Grinding Means

Current Organic Synthesis ◽

10.2174/1570179416666190101122150 ◽

2019 ◽

Vol 16 (3) ◽

pp. 449-457 ◽

Cited By ~ 1

Author(s):

Dong-Xiao Cui ◽

Yue-Dan Li ◽

Jun-Chao Zhu ◽

Yan-Yan Jia ◽

Ai-Dong Wen ◽

...

Keyword(s):

Organic Synthesis ◽

Room Temperature ◽

Michael Reaction ◽

Building Blocks ◽

Solvent Free ◽

Michael Additions ◽

Highly Efficient ◽

Michael Reactions ◽

Michael Adducts ◽

Solvent Free Conditions

Aim and Objective: The direct β-functionalization of trans-β-nitroolefins by Michael reaction is regarded as an efficient way to provide precursors for β-functional amines. However, Michael additions by grinding means with solvent-free conditons are rarely reported. We have developed facile access to β-functional nitroalkanes by grinding means under solvent-free conditions. Materials and Methods: From commercially available materials including ethyl 2-nitroacetate, alkyl 2-cyanoacetates and malononitrile, the grinding reactions between these above-mentioned activated methylenecompounds and various trans-β-nitroolefins were performed at room temperature and solvent-free conditions. Results: A highly efficient direct Michael reaction of nitroolefins by simple grinding means has been developed. Various trans-nitrostyrenes were easily converted into corresponding β-functional nitroalkanes in excellent yields within 5~10 min (up to 36 examples). Conclusion: Herein, we have developed a simple and efficient way to β-functional nitroalkanes through Michael reactions by grinding means. The grinding Michael reaction is fast, clean and stable and these Michael adducts could be easily converted into the other amino compounds served as building blocks in organic synthesis.

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Determining Michael Acceptor Reactivity from Kinetic, Mechanistic, and Computational Analysis for the Base-catalyzed Thiol-Michael Reaction

Polymer Chemistry ◽

10.1039/d1py00363a ◽

2021 ◽

Author(s):

Sijia Huang ◽

Kangmin Kim ◽

Grant Musgrave ◽

Marcus Sharp ◽

Jasmine Sinha ◽

...

Keyword(s):

Computational Analysis ◽

Michael Reaction ◽

Computational Study ◽

Michael Reactions ◽

Michael Acceptor ◽

Michael Acceptors

A combined experimental and computational study of the reactivities of seven commonly used Michael acceptors paired with two thiols within the framework of photobase-catalyzed thiol-Michael reactions is reported. The kinetic...

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Michael Additions of Benzotriazole-Stabilized Carbanions. A Review

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19980599 ◽

1998 ◽

Vol 63 (5) ◽

pp. 599-613 ◽

Cited By ~ 14

Author(s):

Alan R. Katritzky ◽

Ming Qi

Keyword(s):

Steric Hindrance ◽

Electronic Effect ◽

Steric Effects ◽

Unsaturated Ketone ◽

Electronic Effects ◽

Michael Additions ◽

Unsaturated Aldehydes ◽

Michael Acceptor ◽

Michael Acceptors ◽

Electron Withdrawing Group

The 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors is reviewed. The selectivity between 1,4- and 1,2-addition depends significantly on the electronic effect of the carbanion (usually lithium is the counterion), the type of the Michael acceptor, and steric effects. Steric hindrance of the benzotriazolyl group probably enhances the regioselectivity. Normally, 1,4-additions to α,β-unsaturated ketone or ester are observed for carbanions stabilized by a benzotriazolyl group and an electron-withdrawing group (e.g. aryl, vinyl, carbonyl). For α,β-unsaturated aldehydes as Michael acceptors, 1,2-addition is more likely, except where electronic effects are very strong. A review with 39 references.

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Temperature Dependence of the Self-Assembled Styrene Based Random Ionomers in Aqueous Solution

MRS Proceedings ◽

10.1557/proc-775-p6.27 ◽

2003 ◽

Vol 775 ◽

Author(s):

Sung-Hwa Oh ◽

Ju-Myung Song ◽

Joon-Seop Kim ◽

Hyang-Rim Oh ◽

Jeong-A Yu

Keyword(s):

Partition Coefficients ◽

Room Temperature ◽

Aqueous Media ◽

The Self ◽

Spectroscopic Methods ◽

Ion Content ◽

Repeat Units ◽

Notable Effect ◽

Order Of Magnitude ◽

Experimental Errors

AbstractSolution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.

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New from Old: Thorectandrin Alkaloids in a Southern Australian Marine Sponge, Thorectandra choanoides (CMB-01889)

Marine Drugs ◽

10.3390/md19020097 ◽

2021 ◽

Vol 19 (2) ◽

pp. 97

Author(s):

Shamsunnahar Khushi ◽

Angela A. Salim ◽

Ahmed H. Elbanna ◽

Laizuman Nahar ◽

Robert J. Capon

Keyword(s):

Marine Sponge ◽

Tissue Specificity ◽

Spectroscopic Analysis ◽

Transformation Products ◽

Chemical Fractionation ◽

Cancer Tissue ◽

Michael Acceptor ◽

Michael Acceptors ◽

Stable Ring

Thorectandra choanoides (CMB-01889) was prioritized as a source of promising new chemistry from a library of 960 southern Australian marine sponge extracts, using a global natural products social (GNPS) molecular networking approach. The sponge was collected at a depth of 45 m. Chemical fractionation followed by detailed spectroscopic analysis led to the discovery of a new tryptophan-derived alkaloid, thorectandrin A (1), with the GNPS cluster revealing a halo of related alkaloids 1a–1n. In considering biosynthetic origins, we propose that Thorectandrachoanoides (CMB-01889) produces four well-known alkaloids, 6-bromo-1′,8-dihydroaplysinopsin (2), 6-bromoaplysinopsin (3), aplysinopsin (4), and 1′,8-dihydroaplysinopsin (10), all of which are susceptible to processing by a putative indoleamine 2,3-dioxygenase-like (IDO) enzyme to 1a–1n. Where the 1′,8-dihydroalkaloids 2 and 10 are fully transformed to stable ring-opened thorectandrins 1 and 1a–1b, and 1h–1j, respectively, the conjugated precursors 3 and 4 are transformed to highly reactive Michael acceptors that during extraction and handling undergo complete transformation to artifacts 1c–1g, and 1k–1n, respectively. Knowledge of the susceptibility of aplysinopsins as substrates for IDOs, and the relative reactivity of Michael acceptor transformation products, informs our understanding of the pharmaceutical potential of this vintage marine pharmacophore. For example, the cancer tissue specificity of IDOs could be exploited for an immunotherapeutic response, with aplysinopsins transforming in situ to Michael acceptor thorectandrins, which covalently bind and inhibit the enzyme.

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From lithium to sodium: cell chemistry of room temperature sodium–air and sodium–sulfur batteries

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.6.105 ◽

2015 ◽

Vol 6 ◽

pp. 1016-1055 ◽

Cited By ~ 251

Author(s):

Philipp Adelhelm ◽

Pascal Hartmann ◽

Conrad L Bender ◽

Martin Busche ◽

Christine Eufinger ◽

...

Keyword(s):

Energy Density ◽

Large Scale ◽

Room Temperature ◽

Low Cost ◽

Strong Impact ◽

Performance Improvements ◽

Key Issues ◽

Lithium Oxygen Batteries ◽

Open Question ◽

Lithium Sulfur

Research devoted to room temperature lithium–sulfur (Li/S8) and lithium–oxygen (Li/O2) batteries has significantly increased over the past ten years. The race to develop such cell systems is mainly motivated by the very high theoretical energy density and the abundance of sulfur and oxygen. The cell chemistry, however, is complex, and progress toward practical device development remains hampered by some fundamental key issues, which are currently being tackled by numerous approaches. Quite surprisingly, not much is known about the analogous sodium-based battery systems, although the already commercialized, high-temperature Na/S8 and Na/NiCl2 batteries suggest that a rechargeable battery based on sodium is feasible on a large scale. Moreover, the natural abundance of sodium is an attractive benefit for the development of batteries based on low cost components. This review provides a summary of the state-of-the-art knowledge on lithium–sulfur and lithium–oxygen batteries and a direct comparison with the analogous sodium systems. The general properties, major benefits and challenges, recent strategies for performance improvements and general guidelines for further development are summarized and critically discussed. In general, the substitution of lithium for sodium has a strong impact on the overall properties of the cell reaction and differences in ion transport, phase stability, electrode potential, energy density, etc. can be thus expected. Whether these differences will benefit a more reversible cell chemistry is still an open question, but some of the first reports on room temperature Na/S8 and Na/O2 cells already show some exciting differences as compared to the established Li/S8 and Li/O2 systems.

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