Triaryl Phosphites Research Articles

Palladium-Catalyzed Decarbonylative Michaelis-Arbuzov Reaction of Carboxylic Acids and Triaryl Phosphites.

A Pd-catalyzed decarbonylative Michaelis-Arbuzov reaction of carboxylic acids and triaryl phosphites for preparing aryl phosphonates under anhydride-free conditions has been reported. In this context, triaryl phosphites serve as both reagents for activating the carboxylic acids and substrates for the reaction. There have been no reports to date of efficient and direct methods for the in situ activation of carboxylic acids using triaryl phosphites. In comparison to known methods, this reaction avoids the use of organohalides and has an excellent functional group tolerance for the synthesis of various aryl phosphonates from triaryl phosphites and carboxylic acids. This reaction is scalable and applicable to the synthesis of aryl phosphonates featuring bioactive fragments.

Water-Promoted Mild and General Michaelis-Arbuzov Reaction of Triaryl Phosphites and Aryl Iodides by Palladium Catalysis.

A Pd-catalyzed relatively general Michaelis-Arbuzov reaction of triaryl phosphites and aryl iodides for preparing useful aryl phosphonates was developed. Interestingly, water can greatly facilitate the reaction through a water-participating phosphonium intermediate rearrangement process, which also makes the reaction conditions rather mild. In comparison with the known methods, this reaction is milder and more general, as it exhibits excellent functional group tolerance, can be applied to various triaryl phosphites and aryl iodides, and can be extended to aryl phosphonites and phosphinites. A gram-scale reaction with a low catalyst loading also revealed its practicality and potential in large-scale preparation.

Diphenyl Diselenide-Catalyzed Synthesis of Triaryl Phosphites and Triaryl Phosphates from White Phosphorus.

Industrially important triaryl phosphites, traditionally prepared from PCl3, have been synthesized by a diphenyl diselenide-catalyzed one-step procedure involving white phosphorus and phenols, which provides a halogen- and transition metal-free way to these compounds. Subsequent oxidation of triaryl phosphites produces triaryl phosphates and triaryl thiophosphates. Phosphorotrithioates are also prepared efficiently from aromatic thiols and aliphatic thiols.

Palladium-Catalyzed Solvent-Free Preparation of Arylphosphonates ArP(O)(OAr)2from (ArO)3P via the Michaelis–Arbuzov Rearrangement

The Pd-catalyzed Michaelis–Arbuzov rearrangement of triaryl phosphites to produce the corresponding arylphosphonates in good to excellent yields is disclosed. In comparison to the traditional methods, this new method is highly atom efficient and is general, as it can be readily extended to aryl phosphonites and phosphinites. A gram-scale reaction of (PhO)3P to PhP(O)(OPh)2 with low loading of the catalyst was also demonstrated to show its potentially practical usefulness. A plausible mechanism is proposed.

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

AbstractWith interests in alkoxy radical formation on natural and artificial surfaces, a physical‐organic study was carried out with a Hammett series of triaryl phosphites (p‐MeO, H, p‐F, and p‐Cl) to trap adsorbed alkoxy radicals on silica nanoparticles. A mechanism which involves PhC (Me)2O• and EtO• trapping in a cumylethyl peroxide sensitized homolysis reaction is consistent with the results. The p‐F phosphite was able to indirectly monitor the alkoxy radical formation, and 31P NMR readily enabled this exploration, but other phosphites of the series such as the p‐MeO phosphite were limited by hydrolysis reactions catalyzed by surface silanol groups. Fluorinated silica nanoparticles helped to suppress the hydrolysis reaction although adventitious water also plays a role in hindering efficient capture of the alkoxy radicals by the phosphite traps.

Visible Light‐Driven, Photocatalyst‐Free Arbuzov‐Like Reaction via Arylazo Sulfones

AbstractA visible light‐induced formation of Aryl‐Phosphorous bonds starting from arylazo sulfones and triaryl (or trialkyl)phosphites in the absence of any photoredox catalyst and any additives was developed. This reaction showed a broad substrate scope and afforded (hetero)aryl phosphonates in good yields and in up to the gram scale.magnified image

Synthesis of Phosphonates via Michaelis-Arbuzov Reaction

Background: Michaelis–Arbuzov reaction has played a key role for the synthesis of dialkyl or diaryl phosphonates by reacting various alkyl or aryl halides with trialkyl or triaryl phosphite. This reaction is very versatile in the formation of P-C bond from the reaction of aliphatic halides with phosphinites or phosphites to yield phosphonates, phosphinates, phosphine oxides. The Arbuzov reaction developed some methodologies, possible mechanistic pathways, selectivity, potential applications and biologically active various phosphonates. Objective: The synthesis of phosphonates via Michaelis–Arbuzov reaction with many new and fascinating methodologies were developed and disclosed in the literature, and these are explored in this review. Conclusion: This review has discussed past developments and vast potential applications of Arbuzov reaction in the synthesis of organophosphonates. As presented in this review, various synthetic methodologies were developed to prepare a large variety of phosphonates. Improvements in the reaction conditions of Lewis-acid mediated Arbuzov rearrangement as well as the development of MW-assisted Arbuzov rearrangement were discussed. Finally, to achieve high selectivities and yields, fine-tuning of reaction conditions including solvent type, temperature, and optimal reaction times to be considered.

{2-[Bis(2,4-di-tert-butylphenoxy)phosphanyloxy-κP]-3,5-di-tert-butylphenyl-κC1}{3,3′-di-tert-butyl-5,5′-dimethoxy-2,2′-bis[(1,1,2,2-tetraphenylethane-1,2-dioxy)phosphanyloxy-κP]biphenyl}rhodium(I) toluene-d82.7-solvate

The molecule of the title compound, [Rh(C42H62O3P)(C74H68O4P2]·2.7C7D8, consists of two phospharhodacyclic substructures sharing the Rh atom, which are formed by coordination/ortho-metallation of a triaryl phosphite, and by the coordination of a rigid bisphosphite, respectively. The metal displays a tetrahedrally distorted square-planar coordination geometry. Atert-butyl group shows rotational disorder over two positions with refined site occupancy of 0.561 (3):0.439 (3). Two partial-occupancy toluene solvent molecules are disordered over two orientations with site occupancies of 0.5:0.3 and 0.5:0.4, respectively. Intramolecular C—H...O hydrogen bonds are observed. In the crystal, complex molecules and toluene solvent molecules pack as alternating layers parallel to theacplane.

Synthesis of a New Class of Phosphonate Derivatives Using a Three Component Reaction of Trialkyl Phosphites or Triaryl Phosphites in Water

GRAPHICAL ABSTRACT

Synthesis of dialkyl and diaryl benzylphosphonates through a ZnI2-mediated reaction

Several trialkyl and two triaryl phosphites have been tested for their reactivity in the zinc iodide mediated conversion of benzyl alcohol to the corresponding phosphonates. Most react smoothly to afford the desired phosphonate diesters, including hindered and nonracemic phosphites. The implications of this reactivity on the reactions involved in the transformation are discussed.

ChemInform Abstract: Nitrile‐Assisted, Broensted Acid Catalyzed Regio‐ and Stereoselective Diarylphosphonylation of Allyl Silyl Ethers.

AbstractThe reaction of allyl silyl ethers with triaryl phosphites affords functionalized trisubstituted olefins.

ChemInform Abstract: Transition Metal Promoted Ring Expansion of Alkynyl- and Propadienylcyclopropanes

Transition metal promoted ring expansion of alkynyl- and propadienylcyclopropanes is surveyed with emphasis on the Co2(CO)8-mediated reactions developed by the author’s group. A novel rearrangement of 1-(1-alkynyl)cyclopropanols to 2-cyclopenten-1-ones proceeds on complexation of their alkynyl part with Co2(CO)8. In the case of the reactions of 1-alkynylcyclopropanols with an alkyl substituent on the cyclopropane, either 4-substituted or 5-substituted 2-cyclopenten-1-ones can be selectively obtained by appropriate choice of stereochemistry and protective group of the substrates. This rearrangement is successfully applied to cyclopentenone annelation reactions onto cycloalkenes. The rearrangement proceeds catalytically on addition of triaryl phosphite as ligand. The same type of rearrangement proceeds when 1-[o-(1-alkynyl)phenyl]cyclopropanols are employed as substrates; these are converted to 2,3-dihydro-1-naphthalenone derivatives on heating their hexacarbonyldicobalt complexes in 2-propanol. Furthermore, a new type of isomerization-cyclization reaction proceeds to give 3a,4-dihydro-3H-cyclopenta[a]inden-2-one derivatives when the same reaction is carried out in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO). A novel transformation of 1-propadienylcyclopropanols into substituted 1,4-hydroquinones is developed utilizing the interaction of the 1,2-propadienyl group and Co2(CO)8. This reaction is applied to the synthesis of vitamin E and K analogs.

The Role of Structural Effects on the Reactions of Alkoxyl Radicals with Trialkyl and Triaryl Phosphites. A Time-Resolved Kinetic Study

A time-resolved kinetic study on the reactions of alkoxyl radicals with trialkyl and triaryl phosphites ((RO)(3)P: R = Me, Et, i-Pr, t-Bu; (ArO)(3)P: Ar = C(6)H(5), 2,4-(t-Bu)(2)C(6)H(3)) has been carried out. In the (RO)(3)P series, the alkoxyl radicals (cumyloxyl (CumO(*)) and benzyloxyl (BnO(*))) undergo addition to the phosphorus center with formation of intermediate tetraalkoxyphosphoranyl radicals (R'OP(*)(OR)(3): R = Me, Et, i-Pr, t-Bu; R' = Bn, Cum). The addition rate constants are influenced by steric effects, decreasing on going from R = Me to R = t-Bu and from BnO(*) to CumO(*). Rate constants for beta-scission of the phosphoranyl radicals R'OP(*)(OR)(3) have also been determined, increasing, for a given alkyl group R, in the order R' = tert-butyl < R' = benzyl < R' = cumyl and, for a given R' group, on going from R = Me to R = i-Pr. This behavior has been explained in terms of the relative stability of the radicals formed after beta-scission, suggesting moreover that steric effects play in this case a minor role. CumO(*) reacts with triaryl phosphites (ArO)(3)P to give phenoxyl radicals, with rate constants that are influenced to a limited extent by substitution of the aromatic rings. The radical scavenging ability of these substrates is briefly discussed.

Aerobic Photooxidation of Phosphite Esters Using Diorganotelluride Catalysts

Diorganotellurides containing bulky aromatic substituents are found to catalyze the photooxidation of phosphite esters using aerobic oxygen as a terminal oxidant. A Hammett plot with substituted triaryl phosphites yielding rho = 2.88 agrees with a nucleophilic oxygen transfer from telluroxide to phosphite.

Palladium/Phosphite or Phosphate Catalyzed Oxidative Coupling of Arylboronic Acids with Alkynes to Produce 1,4‐Diaryl‐1,3‐butadienes

AbstractThe intermolecular oxidative coupling of arylboronic acids with internal alkynes efficiently proceeds in a 2:2 manner in the presence of palladium acetate, a triaryl phosphite or phosphate, and silver carbonate as catalyst, ligand, and oxidant, respectively, to produce the corresponding 1,4‐diaryl‐1,3‐butadiene derivatives.

Iron−Phosphine, −Phosphite, −Arsine, and −Carbene Catalysts for the Coupling of Primary and Secondary Alkyl Halides with Aryl Grignard Reagents

Simple catalysts formed in situ from iron chloride and a wide range of monodentate and bidentate phosphines and arsines have been screened in the coupling of alkyl halides bearing beta-hydrogens with aryl Grignard reagents. The best of these show excellent activity, as do catalysts formed in situ with monodentate trialkyl and triaryl phosphite ligands. N-heterocyclic carbene-based precatalysts, either preformed or made in situ, also show excellent performance.

A concise method for synthesis of diaryl aryl- or alkylphosphonates

A convenient method has been developed to synthesize diaryl arylphosphonates from triaryl phosphites, triethyl phosphite, and aromatic halides. The new method relies on the triethyl phosphite assisted nickel catalyzed Arbuzov reaction and can be applied to synthesize certain diaryl alkylphosphonates without catalysts.

Polysulfide Reagent in Solid-Phase Synthesis of Phosphorothioate Oligonucleotides: Greater than 99.8% Sulfurization Efficiency

A solution of sulfur (0.1 M) and sodium sulfide (0.01 M) in 3-picoline, referred to as polysulfide reagent, rapidly converts trialkyl and triaryl phosphite triesters to the corresponding phosphorothioate derivatives. Greater than 99.8% average stepwise sulfurization efficiency is obtained in the solid-phase synthesis of DNA and RNA phosphorothioate oligonucleotides via the phosphoramidite approach.

Determination of kinetic parameters and Hammett ρ from the synthesis of triaryl phosphites using reaction calorimetry

Triaryl phosphites bearing electron donating and electron withdrawing substituents were prepared through the reaction of sodium phenoxides with phosphorus trichloride. The reactions were performed in a Mettler RC1 reaction calorimeter. The main purpose of this work was the determination of Hammett ρ from the synthesis of substituted triaryl phosphites through the interpretation of calorimetric data. The phenoxide bearing a methoxide group was the most reactive, and the one bearing the nitro group was the least reactive. It was demonstrated that the reaction rate depends mainly on the addition rate of phosphorus trichloride solution. A good correlation between the Hammet parameters ( σ p + ) was obtained, indicating a reaction mechanism in which a decrease of the negative charge occurs in the transition state.

Rhodium Complex‐Catalyzed Cycloisomerization of Allenenes: Exo and Endo Cyclization Depending on the Auxiliary Ligands.

AbstractFor Abstract see ChemInform Abstract in Full Text.