The Experts below are selected from a list of 468 Experts worldwide ranked by ideXlab platform
Michael J. Krische - One of the best experts on this subject based on the ideXlab platform.
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Enantioselective total and formal syntheses of paroxetine (PAXIL) via phosphine-catalyzed enone α-arylation using arylbismuth(V) reagents: a regiochemical complement to Heck arylation
Tetrahedron, 2006Co-Authors: Phillip K Koech, Michael J. KrischeAbstract:Abstract Exposure of dihydropyridinone 1 to the arylbismuth(V) reagent (p-F-Ph)3BiCl2 in the presence of substoichiometric quantities of Tributylphosphine (10 mol %) results in aryl transfer to the transiently generated (β-phosphonio)enolate to provide the α-arylated enone 2. This transformation, which represents a regiochemical complement to the Mizoroki–Heck arylation, is used strategically in concise formal and enantioselective total syntheses of the blockbuster antidepressant (−)-paroxetine (PAXIL).
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nucleophilic catalysis via phosphine conjugate addition vinyl sulfones as reacting partners in catalytic cross michael cycloisomerization
Synthesis, 2004Co-Authors: Ana Liza Luis, Michael J. KrischeAbstract:Vinylsulfones serve as highly effective reacting partners in Tributylphosphine catalyzed cross-Michael cycloisomerization. In all cases examined, the vinylsulfone moiety exclusively serves as the Michael acceptor to provide 5- and 6-membered ring products as single constitutional isomers in good to excellent yields.
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catalytic enone cycloallylation via concomitant activation of latent nucleophilic and electrophilic partners merging organic and transition metal catalysis
Journal of the American Chemical Society, 2003Co-Authors: Bradley G Jellerichs, Jongrock Kong, Michael J. KrischeAbstract:Upon exposure of mono-enone mono-allylic carbonates to Tributylphosphine and 1 mol % Pd(Ph3P)4, efficient conversion to the corresponding cycloallylated products is achieved. This transformation combines the nucleophilic features of the Morita−Baylis−Hillman reaction with the electrophilic features of the Trost−Tsuji reaction.
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organocatalytic michael cycloisomerization of bis enones the intramolecular rauhut currier reaction
Journal of the American Chemical Society, 2002Co-Authors: Long Cheng Wang, Ana Liza Luis, Kyriacos Agapiou, Hyeyoung Jang, Michael J. KrischeAbstract:The utilization of enones as latent enolates enables regioselective enolate formation from chemically robust presursors. In this communication, we report a catalytic Michael cycloisomerization of bis(enones) under Morita−Baylis−Hillman conditions. Upon exposure to 10 mol % Tributylphosphine, bis(enone) substrates afford both five- and six-membered ring products. Notably, unsymmetrical bis(enones) possessing sufficient steric or electronic bias yield single isomeric products.
Kenneth R Seddon - One of the best experts on this subject based on the ideXlab platform.
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alkyltributylphosphonium chloride ionic liquids synthesis physicochemical properties and crystal structure
Dalton Transactions, 2012Co-Authors: Gabriela Adamova, Ramesh L Gardas, Mark Nieuwenhuyzen, Alberto V Puga, Luis Paulo N Rebelo, Allan James Robertson, Kenneth R SeddonAbstract:A series of alkyltributylphosphonium chloride ionic liquids, prepared from Tributylphosphine and the respective 1-chloroalkane, CnH2n+1Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl)phosphonium chloride is detailed.
Zhizhen Huang - One of the best experts on this subject based on the ideXlab platform.
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morita baylis hillman reaction of α β unsaturated ketones with allylic acetates by the combination of transition metal catalysis and organomediation
Journal of Organic Chemistry, 2016Co-Authors: Haijun Wang, Zhizhen HuangAbstract:An intermolecular Morita–Baylis–Hillman (MBH) reaction of α,β-unsaturated ketones with allylic acetates under the catalysis of 10 mol % of tetrakis(triphenylphosphine)palladium(0) and mediation of Tributylphosphine has been developed in the presence of acetic acid, affording the desired α-coupling products. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity, and moderate to good yields.
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Morita–Baylis–Hillman Reaction of α,β-Unsaturated Ketones with Allylic Acetates by the Combination of Transition-Metal Catalysis and Organomediation
2016Co-Authors: Haijun Wang, Zhizhen HuangAbstract:An intermolecular Morita–Baylis–Hillman (MBH) reaction of α,β-unsaturated ketones with allylic acetates under the catalysis of 10 mol % of tetrakis(triphenylphosphine)palladium(0) and mediation of Tributylphosphine has been developed in the presence of acetic acid, affording the desired α-coupling products. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity, and moderate to good yields
Min Shi - One of the best experts on this subject based on the ideXlab platform.
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phosphine catalyzed highly diastereoselective 3 2 cyclization of isatin derived electron deficient alkenes with α allenic esters
ChemInform, 2011Co-Authors: Xiuchun Zhang, Shuhua Cao, Yin Wei, Min ShiAbstract:Novel [3 + 2] cyclization of isatin alkenes (I) with α-allenic esters (II) in the presence of tris(4-fluorophenyl)phosphine as catalyst leads to (trans,trans)-diastereomer (IV) as major product, whilst the Tributylphosphine-catalyzed reaction proceeds with a moderate (cis,trans)-diastereoselectivity.
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phosphine mediated 3 2 cycloaddition reactions of ethyl 5 5 diarylpenta 2 3 4 trienoates with arylmethylidenemalononitriles and n tosylimines
Journal of Organic Chemistry, 2009Co-Authors: Xiaoyang Guan, Min ShiAbstract:Ethyl 5,5-diarylpenta-2,3,4-trienoates were synthesized and utilized in the phosphine-mediated [3+2] cycloaddition reactions with arylmethylidenemalononitriles and N-tosylimines in the presence of Tributylphosphine. These reactions provide an easy access to a variety of novel polysubstituted cyclopentenes or pyrrolidines in good to excellent yields under mild conditions.
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titanium iv chloride zirconium iv chloride or boron trichloride and phosphine promoted baylis hillman reaction of aldehydes with α β unsaturated ketone
Journal of The Chemical Society-perkin Transactions 1, 2001Co-Authors: Min Shi, Jiankang Jiang, Shicong Cui, Yanshu FengAbstract:In the Baylis–Hillman reaction of aldehydes with an α,β-unsaturated ketone, the chlorinated compound 1 was obtained as the major product using Tributylphosphine as a Lewis base in the presence of titanium(IV) chloride, zirconium(IV) chloride or boron trichloride in dichloromethane at <−20 °C. A plausible reaction mechanism has been proposed. Using (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) as a chiral Lewis base, 10% ee could be achieved. We also found that, if the reaction was carried out at room temperature, the dehydrated compound 3 was obtained as the major product in the Z-configuration.
Norihiro Tokitoh - One of the best experts on this subject based on the ideXlab platform.
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dramatic effect of n substituents in viologens on single electron transfer from Tributylphosphine
Organic and Biomolecular Chemistry, 2005Co-Authors: Shinro Yasui, Atsuyoshi Ohno, Kenji Itoh, Norihiro TokitohAbstract:A single electron transfer (SET) takes place from Tributylphosphine (1a) to 1-alkyl-1'-methylviologens in acetonitrile containing a large amount of methanol under an argon atmosphere. In contrast, no SET takes place from 1a to viologens whose alkyl groups on the nitrogens are larger than the methyl group under the same conditions, 1a instead nucleophilically attacking the viologen to form a covalent adduct. This dramatic substituent effect is discussed in terms of SET occurring within a tight encounter complex formed between the phosphine and the viologen.
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kinetic deuterium isotope effect in single electron transfer occurring from Tributylphosphine to viologens
Chemistry Letters, 2001Co-Authors: Shinro Yasui, Atsuyoshi Ohno, Kenji Itoh, Norihiro TokitohAbstract:Single electron transfer (SET) takes place from Tributylphosphine (1) to 1-methyl-1′-alkyl-4,4′-bipyridinium salts (viologens; 2) in acetonitrile–methanol. Significant kinetic deuterium isotope effect has been observed with respect to hydrogens of a methyl (or an ethyl) substituent in 2. The results are interpreted in terms of SET occurring within a tight encounter complex formed between 1 and 2.
