Vinylphosphonium Salts Research Articles

Sequence-selective three-component reactions of alkyltrifluoroborates with α,β-unsaturated carbonyl compounds and vinylphosphonium salts

A photocatalytic three-component reaction of alkyltrifluoroborates with two electron-deficient alkenes proceeds in a sequence-selective manner, which can be followed by Wittig olefination to afford γ,δ-unsaturated ketones and esters.

Vinylphosphonium and 2-aminovinylphosphonium salts - preparation and applications in organic synthesis.

The main synthetic routes towards vinylphosphonium salts and their wide applications in organic synthesis are discussed in this review. Particular attention is paid to the use of these compounds as building blocks for the synthesis of carbo- and heterocyclic systems after their prior transformation into the corresponding phosphorus ylides, followed by the intramolecular Wittig reaction with various types of nucleophiles containing a carbonyl function in their structures.

ChemInform Abstract: Addition of Sulfonic Acids to Terminal Alkynes Catalyzed by a Rhodium Complex: Ligand Concentration‐Controlled Reaction Selectivity.

A Rh-catalyzed process for the regioselective formation of vinyl sulfonate esters in moderate to high yields through the hydrosulfonation of alkynes with sulfonic acids has been developed. Our synthetic approach is capable of adding a variety of alkynes to a set of sulfonic acids and is amenable to different phosphorus ligands, solvents, and Rh precursors. We control the chemo- and regioselectivity of the reaction to the Markovnikov vinyl sulfonate ester by tuning the concentration of the exogenous ligand, PPh3, which forms the active RhP species in situ. At lower PPh3 concentrations, the reaction favors the formation of vinyl sulfonate esters, whereas at higher PPh3 concentrations, the reaction favors the formation of vinylphosphonium salts. We perform Hammett analyses and kinetic isotope effect experiments to determine the steps of the catalytic mechanism. Reaction data for substituted acetylenes indicates syn and anti addition occur across the triple bond. Experiments performed with the vinylphosphonium salt as the exogenous ligand determined that the formation of the salt was not a necessary step in the catalytic mechanism for the direct formation of the vinyl sulfonate esters.

ChemInform Abstract: Three‐Component Reaction of Triphenylphosphine, Acetylenic Esters, and 6‐Aminouracil or 6‐Amino‐N,N′‐dimethyluracil.

Abstract Protonation of the reactive 1:1 intermediate produced in the reaction of acetylenic esters and triphenylphosphine by 6-aminouracil or 6-amino-N,N′-dimethyluracil leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the NH acid to produce highly fanctionalized, salt-free phosphorus ylides in excellent yields.

ChemInform Abstract: Mechanism of Formation of Aromatic Vinylphosphonium Salts via the Peterson Olefination.

AbstractPara substituents in aromatic aldehydes determine the E/Z‐selectivity in the Peterson olefination due to their electron‐donating or ‐withdrawing character.

Addition of Sulfonic Acids to Terminal Alkynes Catalyzed by a Rhodium Complex: Ligand Concentration‐Controlled Reaction Selectivity

AbstractA Rh‐catalyzed process for the regioselective formation of vinyl sulfonate esters in moderate to high yields through the hydrosulfonation of alkynes with sulfonic acids has been developed. Our synthetic approach is capable of adding a variety of alkynes to a set of sulfonic acids and is amenable to different phosphorus ligands, solvents, and Rh precursors. We control the chemo‐ and regioselectivity of the reaction to the Markovnikov vinyl sulfonate ester by tuning the concentration of the exogenous ligand, PPh3, which forms the active RhP species in situ. At lower PPh3 concentrations, the reaction favors the formation of vinyl sulfonate esters, whereas at higher PPh3 concentrations, the reaction favors the formation of vinylphosphonium salts. We perform Hammett analyses and kinetic isotope effect experiments to determine the steps of the catalytic mechanism. Reaction data for substituted acetylenes indicates syn and anti addition occur across the triple bond. Experiments performed with the vinylphosphonium salt as the exogenous ligand determined that the formation of the salt was not a necessary step in the catalytic mechanism for the direct formation of the vinyl sulfonate esters.

Three-Component Reaction of Triphenylphosphine, Acetylenic Esters, and 6-Aminouracil or 6-Amino-N,N′-dimethyluracil

Protonation of the reactive 1:1 intermediate produced in the reaction of acetylenic esters and triphenylphosphine by 6-aminouracil or 6-amino-N,N′-dimethyluracil leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the NH acid to produce highly fanctionalized, salt-free phosphorus ylides in excellent yields.

Diastereoselective Synthesis of Stable Phosphorus Ylides by a Three-Component Reaction between Triphenylphosphine, Dialkyl Acetylenedicarboxylates and 3-(Arylsulfonylhydrazono)Butanoates

Protonation of the reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine by 3-(arylsulfonylhydrazono)butanoates leads to vinylphosphonium salts which undergo Michael addition with the conjugate base of the CH-acid to produce highly functionalised, salt-free phosphorus ylides in a diastereoselective manner and excellent yields.

Mechanism of Formation of Aromatic Vinylphosphonium Salts via the Peterson Olefination

The mechanism of the reaction of tributyl[(trimethylsilyl)methylene]phosphorane with benzaldehyde and its p-substituted analogues has been examined. It has been found that the electronic nature of the p-substituents in aromatic aldehydes strongly influences the stereochemical and kinetic outcome of the Peterson olefination whereas temperature substantially affects their Hammett correlation. This indicates that the Peterson olefination is a multistep reaction involving the formation of at least an oxyanion/betaine and a carbanion as intermediates. In turn, moderate Z-selectivity might be the result of “steric approach intermediate control”; however, E-selectivity seems to result from the silicon–oxygen interaction and interactions of steric substituents in competing erythro- and threo-betaines.

Cycloaddition Reactions of Propiolamidinium Salts

AbstractThermal and microwave‐assisted [3+2] cycloadditions between differently substituted propiolamidinium tetraphenylborates 3a–d and N‐methyl‐C‐phenylnitrone, benzyl azide, and N‐(3‐azidopropyl)phthalimide were studied. The activation parameters of the [3+2] cycloaddition between alkyne 3a and benzyl azide were determined. A Diels–Alder reaction between the terminal alkyne 3a and cyclopentadiene could be achieved with the aid of microwave activation. The reaction between 3a and triphenylphosphorane imine provides the β,β‐bis(dimethylamino)vinylphosphonium salt 21, which might or might not have been formed through an initial [2+2] cycloaddition reaction.

Synthesis of Dialkyl 2-(Dialkoxyphosphoryl)-3-(4-oxo-4,5-dihydro-thiazole-2-yl Sulfanyl) Succinates

A three-component reaction of trialkyl(aryl) phosphites, dialkyl acetylenedicarboxylates and rhodanine is described as a simple and efficient route for synthesis of dialkyl 2-(dialkoxyphosphoryl)-3-(4-oxo-4,5-dihydro-thiazole-2-yl sulfanyl) succinates in good yields. Protonation of the reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylate and triphenylphosphine by N′-formylbenzohydrazide leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the NH acid to produce highly functionalized, salt-free phosphorus ylides in excellent yields.

Three-Component Coupling Catalyzed by Phosphine: Preparation of α-Amino γ-Oxo Acid Derivatives

The three-component coupling reaction of ethyl propiolate (1), phthalimide (2), and aldehyde (3) catalyzed by tripheny- lphosphine, was developed. A solution of an equivalent amount of 1 and 2 in benzaldehyde (3a) in the presence of 30 mol% of PPh3 was heated at 100?C for 48 h to give N-(1-ethoxycarbonyl-3-oxo-3-phenylpropyl)phthalimide (4a) in 83% yield. This reaction was thought to proceed via vinylphosphonium salt formed from the reaction of ethyl propiolate (1) with triphenylphosphine in situ.

Three-Component Reaction between Triphenylphosphine, Dialkyl Acetylenedicarboxylates and 3-(3,5-Dimethyl Pyrazol-1-yl)-3-oxo Propionitrile

Protonation of the reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine by 3-(3,5-dimethyl pyrazol-1-yl)-3-oxopropionitrile leads to vinylphosphonium salts which undergo Michael addition with the conjugate base of the CH-acid to produce highly functionalised, salt-free phosphorus ylides in excellent yields.

ChemInform Abstract: Reverse Microemulsions-Mediated Synthesis of Vinylphosphonium Salts.

Abstract PPH 3 reacts with activated alkynes in reverse (water-hydrocarbon) microemulsions giving specifically rise to a mixture of Z and E triphenylvinylphosphonium salts which are readily isolated in good yields.

ChemInform Abstract: Reaction of Olefins with Dimethyl(methylthio)sulfonium Salts in the Presence of Triphenylphosphine. Preparation of Vinylphosphonium Salts.

Olefins were effectively converted into the corresponding (2-methylthioalkyl)triphenylphosphonium salts by the reaction with dimethyl(methylthio)sulfonium salts in the presence of triphenylphosphine. 2-Triphenylphosphonioalkyldimethylsulfonium salts, synthesized by alkylation of the corresponding methylthiophosphonium salts, react with 1,8-diazabicyclo[5.4.0]undec-7-ene or aq NaOH to afford the corresponding vinylphosphonium salts or vinylphosphine oxides in good yields.

ChemInform Abstract: Additions of Nucleophiles to Vinyl Phosphonium Salts. A Useful Way to Obtain New Synthons.

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A Facile, One-Pot Synthesis of Azoic Compounds and Anthraquinone Derivatives Containing Dialkyl Phosphoryl Moieties in Multicomponent Reactions

Protonation of the reactive 1:1 intermediates produced in the reactions between triphenylphosphine and dialkyl acetylenedicarboxylates by 1-amino-anthraquinone or 1,5-diphenylcarbazone as a core dye leads to vinyl phosphonium salts, which undergo Michael addition with conjugate base of NH compounds to produce stable phosphorus ylides as novel dyes in fairly good yields. These ylides can exist in two geometrical isomers (Z) and (E) for 3, because the negative charge of the ylide moiety of these compounds are strongly conjugated with the adjacent carbonyl group. Rotation around the carbon–carbon double bond is slow in the (Z) and (E) geometrical isomers on the NMR time scale at ambient temperature. These compounds are assigned by their IR, 1H, 13C NMR spectral data as well as their mass spectroscopic data.

ChemInform Abstract: Stereoselective Synthesis of Tetraalkyl Cyclobutene-1,2,3,4-tetracarboxylates. Synthesis of Tetraalkyl (Z,Z)-Buta-1,3-diene-1,2,3,4-tetracarboxylates.

Tetraalkyl cyclobutene-1,2,3,4-tetracarboxylates, prepared by intramolecular Wittig reaction between a vinylphosphonium salt and diethyl 2-oxobutanedioate, undergo electrocyclic ring-opening reactions, in boiling toluene, to produce highly electron-deficient 1,3-dienes.

Three-component reaction between triphenylphosphine, dialkyl acetylenedicarboxylate and 4-amino-5-alkyl-2,4-dihydro-1,2,4-triazole-3-thiones: an efficient one-pot synthesis of stable phosphorus ylides

Protonation of the reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine by 4-amino-5-alkyl-2,4-dihydro-1,2,4-triazole-3-thione leads to vinylphosphonium salts which undergo Michael addition with the conjugate base of the NH-acid to produce highly functionalized, salt-free phosphorus ylides in excellent yields.

Trans‐A2B‐corroles Bearing a Coumarin Moiety ‐ From Synthesis to Photophysics

Four dyads comprised of corrole and coumarin units have been synthesised. Three coumarincarboxaldehydes were synthesized and transformed into the corresponding trans-A(2)B-corroles by reaction with 5-(pentafluorophenyl)dipyrromethane. It has been proven that this type of direct condensation can lead to the corresponding corroles in moderate yields. The reaction of hydroxybenzaldehydes with vinylphosphonium salts has been identified as the most general method for the preparation of formyl-coumarins with various patterns of substituents. The dyad consisting of ketobiscoumarin and corrole was synthesized by Sonogashira coupling. Spectroscopic and photophysical investigations revealed that there is an efficient energy transfer from the coumarin moiety to corrole in all four dyads. Energy transfer can be clearly ascribed to a dipole-dipole mechanism (Förster) for all dyads that contain luminescent coumarins and to an electron exchange mechanism (Dexter) for the dyad with the non-luminescent one. In the case of the dyad that bears coumarin with a hydroxy group at position 5, an electron-transfer was detected from corrole to coumarin. The latter process is possible because of the suitably low reduction potential of coumarins of this type.