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Tertiary phosphines have been recognized as powerful organocatalysts for the Michael reaction, which is one of the most important atom-economical methods for carbon-carbon and carbon-heteroatom bond construction. In the presence of tertiary phosphines, a vast array of Michael acceptors and Michael donors can be coupled with each other under neutral and metal-free conditions to produce useful densely functionalized molecules. This review highlights the role of phosphine-catalyzed Michael reaction in cutting-edge areas, such as asymmetric synthesis, natural products synthesis, drug design, and polymer material science. As the central part of catalysis science, the kinetic and mechanistic issues are also discussed when possible. The review is organized by the type of the Michael acceptor and the Michael donor used in the reaction. [ABSTRACT FROM AUTHOR]

Tertiary phosphines (n -Bu 3 P, Ph 3 P) efficiently catalyze the vicinal bis-addition of dialkyl phosphites and diaryl phosphine oxides to alkynoates though the tandem α-umpolung/β-Michael addition. This reaction offers a simple metal-free method for gram-scale preparation of practically useful bisphosphonates and bisphosphine oxides under mild conditions with high atom economy and selectivity. Image 1 • Tertiary phosphines catalyze vicinal bis-addition of P(O) H compounds to alkynoates. • Very simple conditions were developed. • Gram-scale synthesis of bisphosphonates and bisphosphine oxides was performed. [ABSTRACT FROM AUTHOR]

The previously proposed mechanism for phospha-Michael addition of tertiary phosphines to electron-deficient alkenes has been amended according to the secondary kinetic isotope effects provided by α-deuterated activated alkenes. The data obtained have shown that rate-determining protonation of intermediate phosphonium zwitterion proceeds not directly at its carbanionic center but first at a heteroatom of the attached electron-withdrawing group, with subsequent isomerization of the enolic/eniminic intermediate to stable keto-/cyanophosphonium product. [ABSTRACT FROM AUTHOR]

2‐d‐Acrylamide was synthesized via the 2‐step procedure starting from acrylonitrile and deuterium oxide. This procedure affords 2‐d‐acrylamide in 99.9% chemical purity and 98.4% isotopic enrichment. [ABSTRACT FROM AUTHOR]

The PBu 3 -catalyzed conjugate addition of diphenylphosphine oxide to unsubstituted and substituted electron-deficient alkenes is reported. β-Substituted α,β-unsaturated esters, trans -methyl crotonate and trans -methyl cinnamate, known for their reluctance to participate in phosphine-catalyzed transformations, also react well under the developed conditions. Mild reaction conditions, simple work-up and the ease of catalyst recovery make the proposed methodology useful for the preparation of functionalized tertiary phosphine oxides. The utility of this method was demonstrated by the gram-scale reactions of diphenylphosphine oxide with electron-deficient alkenes. [ABSTRACT FROM AUTHOR]

ABSTRACT Bifunctional tertiary phosphines with hydrogen-bonding functionalities have recently received a considerable amount of attention due to their efficient application in organocatalysis. To estimate the potential role of the carboxyl group in specific interactions with reaction intermediates, the kinetics of the reactions of 2-(diphenylphosphino)benzoic acid (2-DPPBA) and 4-(diphenylphosphino)benzoic acid (4-DPPBA) with acrylic acid and acrylonitrile was studied in different solvents, and the data were compared with the results obtained previously for the related reactions of triphenylphosphine. The solvent effect on the reaction kinetics was found to be identical to all of the phosphines, suggesting that H bonding with the solvent has no specific influence on the rate for bifunctional tertiary phosphines. Despite of the electron-withdrawing effect of the carboxyl group, the rate of reaction of 2-DPPBA with acrylic acid is 1.4-2.1 times larger than that of triphenylphosphine, implying participation of the neighboring CO2H group of the phosphine in stabilization of the intermediate zwitterion by intramolecular H bonding with the carbonyl oxygen atom of the acrylic acid as a proton acceptor center. The results show that this trend of reactivity was not applicable when acrylonitrile was used as an electrophilic partner since the 2-DPPBA was less reactive than triphenylphosphine. The presence of sp-hybridized atoms of the nitrile group makes intramolecular H bonding with the nitrogen atom of the generated zwitterion strongly disfavored, but leaves the possibility for the H bonding with π electrons of the CN group. Similar effects of anchimeric assistance were not observed for the 4-DPPBA due to disability of the carboxyl group in the para position to participate in any intramolecular H bonding with the reaction intermediates. [ABSTRACT FROM AUTHOR]

An efficient PBu 3 -catalyzed α-addition of the P(O)–H bond to ethyl phenylpropiolate has been developed. This strategy offers a facile method for the preparation of synthetically useful alkenyl phosphonates and phosphinates proceeding under neutral reaction conditions with high atom economy. [ABSTRACT FROM AUTHOR]

ABSTRACT In aprotic solvents, kinetics of the reaction of triphenylphosphine with acrylic acid is second order in the acid and first order in the phosphine. To find the most suitable model to describe the solvent effect on this reaction, the third-order rate constants in a series of 16 aprotic solvents were analyzed using one- and multiparameter regressions within the framework of the Kamlet-Taft, the Catalán, the Gutmann-Mayer, and the Koppel-Palm equations. The best result gives a two-parameter model constructed on the basis of the Reichardt polarity ET and the basicity B from the Koppel-Palm equation, with the weak positive effect of the ET parameter on the reaction rate and very strong negative effect of the B parameter. The results obtained give further evidence to the previously suggested a stepwise mechanism, which involves the initial formation of a zwitterionic intermediate, followed by the proton transfer from the second molecule of acrylic acid to the generated carbanionic center in the rate-determining step. [ABSTRACT FROM AUTHOR]

ABSTRACT Quaternization of triphenylphosphine with maleic and cis-aconitic acids is strongly accelerated by participation of the cis-carboxyl group in stabilization of the phosphonium zwitterion intermediate by intramolecular hydrogen bonding, in spite of steric hindrance by the acid's reaction center. A similar effect for trans-isomeric acids is not observed, which can be rationalized on the basis of spatial structures of the generated zwitterions, implying an electrostatic interaction between the phosphonium center and carbonyl oxygen atom. The effect of anchimeric assistance decreases when the intramolecular hydrogen bonding disfavors attack of the phosphine on the sterically less hindered carbon atom of the C=C bond, as observed for cis-aconitic acid. [ABSTRACT FROM AUTHOR]

Kinetic data provide evidence that proton transfer to the carbanion centre of a phosphonium zwitterion is the rate-determining step in quarternization reactions of triphenylphosphine with electron-deficient alkenes in solution. This conclusion is based on the third-order , the reactivity of the alkenes, and solvent isotope effects in deuteroacetic acid. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The structures of intermediates and transition states in the reaction of tertiary phosphines with unsaturated carboxylic acids have been calculated at the B3LYP level of theory using the 6-31+G(d,p) basis set. Analysis of the results shows that [1,3]-intramolecular migration of carboxylic proton to carbanionic center of generated zwitterionic intermediate is strongly kinetically unfavorable, and external proton-donor source is essential to complete quaternization. A molecular cluster of the intermediate with one molecule of water has been modeled for intermolecular reaction pathway, but even in this case, the proton transfer remains to be the rate-determining step that is in a good agreement with previous kinetic investigations on this reaction. The data obtained for this reaction have much in common with recent studies on the mechanisms of the Morita-Baylis-Hillman reaction and phosphine-catalyzed [3+2] cycloaddition, which revealed paramount importance of proton-transfer steps. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The Michael-type addition of tertiary phosphines to electron-deficient alkenes is a convenient way to generate reactive phosphonium zwitterionic intermediates, which participate readily in many synthetically useful transformations. Although the synthetic usefulness of the phospha–Michael addition has been largely demonstrated, knowledge on the kinetics and mechanism of this reaction is sparse. This paper briefly summarizes the contribution of our research group to find out the mechanism of this reaction. [ABSTRACT FROM PUBLISHER]

The catalytic activity of hexamethyltriaminophosphine in the P(O)–H bond addition to electron-deficient alkenes was studied. Depending on the nature of the alkene, hexamethyltriaminophosphine produces better or lower yields of the reaction products compared to tri-n-butylphosphine. [ABSTRACT FROM AUTHOR]

The kinetics of the reaction of tertiary phosphines with acrylic acid in a series of aprotic solvents was studied by spectrophotometry. The data obtained suggest a stepwise mechanism of interaction including initial formation of zwitterionic intermediate followed by intermolecular proton transfer to the generated carbanionic center from the second molecule of acrylic acid. [ABSTRACT FROM AUTHOR]

Reactions of tertiary phosphines with unsaturated electrophilic reagents are widely used in synthetic organic chemistry. Typical satellites of these transformations are proton migration processes, which can play decisive role in such reactions. To learn more about proton transfer mechanism, kinetics of reaction of triphenylphosphine with a series of unsaturated carboxylic acids in alcohols, carboxylic acids, and aprotic solvents was studied by spectrophotometry. The form of kinetic equation depends on proton-donor properties of solvent and has a general third order. Proton transfer occurs from the solvent in carboxylic acids; the second molecule of substrate is required in aprotic solvents, and both canals of proton migration take place in alcohols. Existent proton transfer canals are isokinetic, attesting to the invariability of general features of the reaction mechanism independent of proton-donor nature at the last step of the interaction. A stepwise mechanism including initial generation of 1,3-dipole followed by proton transfer to the carbanionic centre from the medium is suggested. [ABSTRACT FROM AUTHOR]

Conjugate addition of diisobutyl phosphite to activated alkenes under PBu3catalysis affords corresponding phosphonates in high yields within short reaction times. [ABSTRACT FROM PUBLISHER]

The optimized reaction conditions allow the regio- and stereoselective synthesis of alkenyl phosphonates. [ABSTRACT FROM AUTHOR]