Effects of substituents on aryl groups during the reaction of triarylphosphine radical cation and oxygen

In a previous report (S. Yasui, S. Tojo and T. Majima, J. Org. Chem., 2005, 70, 1276), we presented the results from the laser flash photolysis (LFP) and product analysis of the 9,10-dicyanoanthracene (DCA)-photosensitized oxidation of triarylphosphine (Ar(3)P) in acetonitrile under air, which showed that the photoreaction results in the oxidation of Ar(3)P to give the corresponding phosphine oxide (Ar(3)P=O) in a nearly quantitative yield, and that the reaction is initiated by the electron transfer (ET) from Ar(3)P to DCA in the singlet excited state ((1)DCA*), producing the triarylphosphine radical cation Ar(3)P (+). This radical cation decays through radical coupling with O(2) to afford the peroxy radical cation Ar(3)P(+)-O-O*, which we proposed to be the intermediate leading to the product Ar(3)P=O. We now examined this photoreaction in more detail using ten kinds of Ar(3)P with various electronic and steric characteristics. The decay rate of Ar(3)P*(+) measured by the LFP was only slightly affected by the substituents on the aryl groups of Ar(3)P. During the photolysis of trimesitylphosphine (Mes(3)P), the peroxy radical cation intermediate (Mes(3)P(+)-O-O*) had a lifetime long enough to be spectrophotometrically detected. The quantum yields of Ar(3)P=O increased with either electron-withdrawing or -releasing substituents on the aryl groups, suggesting that a radical center is developed on the phosphorus atom during the step when the quantum yield is determined. In addition, the o-methyl substituents in Ar(3)P decreased the quantum yield. These results clearly indicated that Ar(3)P(+)-O-O* undergoes radical attack upon the parent phosphine Ar(3)P that eventually produces the final product, Ar(3)P=O.     

Markovnikov hydroformylation catalyzed by ROPAC in the presence of phosphine and phosphine oxide ligands

Rhodium-catalyzed hydroformylation of 1-octene in the presence of different phosphine and phosphine oxide ligands has been investigated. The molecular structure of new phosphine ligand, fluorenylidine methyl phenyl diphenylphosphine, was determined by single-crystal X-ray crystallography. Parameters such as different ligands, molar ratio of ligand to rhodium complex, ratio of olefin to rhodium complex, pressure of CO : H₂ mixture, and time of the reaction were studied. The linear aldehyde was the main product when the phosphine ligands were used as auxiliary ligands while the selectivity was changed to the branched products when the related phosphine oxide ligands were used. Under optimized reaction conditions, in the presence of [Rh(acac)(CO)(Ph₃P)]-di(1-naphthyl)phenyl phosphine oxide, conversion of 1-octene reached 97% with 87% selectivity of branched aldehyde.     

Preconcentration of gold,silver, palladium,platinum, and ruthenium with organophosphorus extractants

Extraction of noble metals in acid media with new tertiary phosphines and phosphine chalcogenides was examined. Tristyrylphosphine, tristyrylphosphine sulfide tris(2-phenylethyl)phosphine oxide, tris-(2-phenylethyl)phosphine sulfide, bis(2-phenylethyl)[2-(propylthio)ethyl]phosphine oxide, bis(2-phenylethyl)-[2-(butylthio)ethyl]phosphine oxide, and tris[2-(butylthio)ethyl]phosphine oxide were used as extractants. The suitability of the extractants for determination of Au, Ag, and Pd in rock and ore samples was elucidated.     

NMR spectrometric study of molecular complex formation of [60]- and [70]fullerenes with a number of phosphine oxides

Molecular complex formation between [60]- and [70]fullerenes with a series of phosphine oxides, namely, tri-n-octyl phosphine oxide, triphenyl phosphine oxide and tri-n-butyl phosphine oxide has been studied in CCl4 medium by NMR spectrometric method. Both [60]- and [70]fullerenes have been shown to form 1:1 adducts with the above series of phosphine oxides. Formation constants (K) for all the complexes have been determined from the systematic variation of NMR chemical shifts of specific protons of the donors in presence of [60]- and [70]fullerenes. Trends in the values of K suggest that [70]fullerene binds stronger with the phosphine oxides relative to [60]fullerene.     

Synthesis and use of borane and platinum(II) complexes of 3‐diphenylphosphino‐1‐ phenylphospholane (LuPhos)

3‐Diphenylphosphinoyl‐1‐phenylphospholane 1‐oxide ( 2 ) obtained by the Michael addition of diphenylphosphine oxide to the double‐bond of 1‐phenyl‐2‐phospholene 1‐oxide ( 1 ) was subjected to double deoxygenation to afford the corresponding bisphosphine ( 3 , LuPhos) that was converted to bis(phosphine borane) 4 and to cis chelate platinum(II) complex 6 . A mixed phosphine oxide–phosphine borane 5 was also prepared. Stereostructures of the bidentate P‐ligand 3 and the ring platinum(II) complex ( 6 ) were evaluated by quantum chemical calculations. Complex 6 used as a catalyst showed modest activity, but unusual regioselectivity in the hydroformylation of styrene and its 4‐substituted analogues. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:730–736, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20741     

Furfuryl-containing tertiary phosphine oxides and polymers based on some of them

The syntheses of dimethyl(furfuryloxymethyl)phosphine oxide (DPO), methylbis(furfuryloxymethyl)phosphine oxide (MPO), tris(furfuryloxymethyl)phosphine oxide (TPO), dimethyl(tetrahydrofurfuryloxymethyl)phosphine oxide (DTPO), methyl-bis(tetrahydrofurfuryloxymethyl)phosphine oxide (MTPO) and tris(tetrahydrofurfuryloxymethyl)phosphine oxide (TTPO) from dimethyl(chloromethyl)phosphine oxide, methyl-bis(chloromethyl)phosphine oxide, tris(chloromethyl)phosphine oxide and the furfuryl and tetrahydrofurfuryl sodium alkoxides via the Williamson reaction are reported. Phosphorus-containing furan polymers with reduced flammability are prepared by polymerizing MPO and TPO using p-toluenesulphonic acid as catalyst. The oxygen indexes of these polymers, as determined by ASTM D-2863, are 35.1 and 33.1% O₂, respectively; for the phosphorus-free polymer from difurfurylidene acetone, it is 23.0% O₂. It is shown that DPO can be used as an efficient fire-retardant for reducing the flammability of a polymer from difurfurylidenacetone.     

SYNTHESIS OF HYDROPHILIC ULTRAFINE NANOPARTICLES COORDINATED WITH CARBOHYDRATE CLUSTER

A hydrophilic phosphine oxide (1) as a suitable ligand for semiconductor nanoparticles was synthesized. The hydrophilicity of the phosphine oxide was enhanced by introduction of three mannose moieties to the end of the molecule via amide linkages. The ligand 1 was able to coordinate to the CdSe/ZnS nanoparticle making the newly formed hydrophilic complex.     

Reactions of (1-Bromoethenyl)(diphenyl)phosphine Oxide with NH-, OH-, and SH-Nucleophiles

Russian Journal of General Chemistry - The reactions of (1-bromoethenyl)(diphenyl)phosphine oxide with NH-, OH-, SH-nucleophiles were studied. The reaction of phosphine oxide with alcohols and...     

Organophosphorus chemistry. Part 21 [1]. Insertion of olefins into P  CF3 bonds

Tris(trifluoromethyl)phosphine and ethylene reacted efficiently under u.v. irradiation to give 3,3,3-trifluoropropylbis(trifuomothyl) phosphine in good yield. With vinyl fluoride, vinylidene fluoride, and propene the reaction was regioselective rather than regiospecific, and the yield of 1:1 adduct was low. In these reactions, and in those with vinyl chloride, but-1-ene, and hexafluoropropene, in which only traces of 1:1-adduct could be detected, the bulk of the olefin and of the phosphine was recovered, and numerous by-products consistent with radical intermediates were identified. With propyne, 1,1,1-trifluoro-3-bis(trifluoromethyl)phosphino-cis-but-2-ene was obtained in moderate yield, but no reaction occurred between the phosphine and either but-2-yne or hexafluorcbut-2-yne. Tris(trifluoromethyl)phosphine oxide did not form an adduct with ethylene, tetrafluoroethylene, or propyne.Bis(trifluoromethyl)phosphine and dimethylphosphine both reacted readily under u.v. irradiation with 3,3,3-trifluoropropene, the phosphinyl radical attacking the terminal carbon in each case.     

Evaluation of acylphosphine oxide polymerization initiators using differential scanning calorimetry

This study examines the polymerization of dental monomers catalyzed by synthesized acylphosphine oxides in a differential scanning calorimetry (DSC) cell. This research focuses on establishing a relationship between radicals generated by the acylphosphine oxide photoinitiators and the kinetic reaction rates of methyl methacrylate (MMA) and acrylamide (ACM), a model monomer. The thermal stability of mono- and di-acylphosphine oxides was examined by DSC. Endothermic melting and exothermic polymerization reactions initiated with the two initiators were recorded. The acrylamide model system laid the ground work for the critical evaluation of the synthesized new initiators of mono (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide. The bis(acyl) phosphine oxide photoinitiator was more reactive than the mono-(acyl) phosphine oxide with methyl methacrylates under laboratory conditions. In exothermic reactions, temperatures rose higher and more rapidly for bis(acyl) phosphine oxide initiated reactions than mono-(acyl) phosphine oxide initiated reactions.     

Chiral phosphine oxide BINAPO as a Lewis base catalyst for asymmetric allylation and aldol reaction of trichlorosilyl compounds

Chiral phosphine oxide BINAPO, which was readily prepared from chiral phosphine BINAP, exhibited good catalytic activities in the reaction of trichlorosilyl compounds via hypervalent silicate intermediates. The allylation of aldehydes with allyltrichlorosilanes in the presence of a catalytic amount of BINAPO gave the allylated adducts in good enantioselectivities (up to 79% ee) wherein a combination of diisopropylethylamine and tetrabutylammonium iodide as additives was crucial to accelerate the catalytic cycle. ³¹P NMR analysis of the phosphine oxide suggested that the amine promoted the dissociation of phosphine oxide from silicon atom. BINAPO also promoted the enantioselective aldol reaction of aldehydes with trichlorosilyl enol ethers in the presence of diisopropylethylamine as an additive to afford the corresponding aldol adducts in high diastereo- and enantioselectivities (up to syn/anti=1/25, 96% ee (anti)).     

Electrophilic and Nucleophilic Addition Reactions of α,β-Unsaturated Diphenylphosphoryl Compounds

Russian Journal of Organic Chemistry - Procedures were developed for the synthesis of diphenyl(prop-1-en-1-yl)phosphine oxide and cyclohex-1-en-1-yl(diphenyl)phosphine oxide by alkaline hydrolysis...     

Studies on highly regio- and stereoselective fluorohydroxylation reaction of 3-aryl-1,2-allenyl phosphine oxides with Selectfluor

The fluorohydroxylation of allenyl phosphine oxides with Selectfluor in commercial MeCN without prior treatment or a mixed solvent of anhydrous MeCN (refluxed over CaH₂ and distilled before use) and 7.0 equiv of H₂O or MeNO₂/H₂O=10/1 afforded 2-fluoro-3-hydroxy-1(E)-alkenyl diphenyl phosphine oxides in moderate yields with very high regio- and stereoselectivities. The E-stereoselectivity is believed to be controlled by the phosphine oxide functionality. In the reaction of 3-(4-methoxyphenyl)-1,2-propadienyl diphenyl phosphine oxide, further fluorination on the electron-rich phenyl ring was also observed.     

葡萄糖衍生物的手性膦化合物的合成及结构研究

研究葡萄糖吡喃环上同时含有官能团环氧乙烷基和对甲苯磺酸酯时与二苯基膦锂的反应, 一种新的手性膦被得到。它的膦氧化物的晶体结构被测定, 构象为椅式(1C4), 吡喃环上的五个取代基均在直立键上。     

Reaction of 3-thiolene 1,1-dioxide with PH-acids

The nucleophilic addition of 2-phenylethylphosphine, bis(2-phenylethyl)phosphine oxide, and bis(2-phenylpropyl)phosphine oxide to 3-thiolene 1,1-dioxide catalyzed by the KOH-DMSO system leads to bis(3-thioanil) (2-phenylethyl)phosphine oxide, bis(2-phenylethyl) (3-thianil)phosphine oxide, and bis(2-phenylpropyl) (3-thioanil)phosphine oxide, respectively.Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1195–1198, September, 1998.     

Oxidation of an Internal-Edge-Substituted [5]Helicene-Derived Phosphine Synchronously Enhances Circularly Polarized Luminescence

Small chiral organic molecules with CD properties are in high demanded due to their potential use in promising electronic and biological applications. Herein, we reveal a system in which the oxidation of a phosphino group to the corresponding phosphine oxide on the inner rim of a helicene derivative induces a CPL response. Laterally π-extended 7,8-dihydro[5]helicenes bearing phosphine and phosphine oxide groups on their inner helical rims (i. e., the C1 position) were synthesized, and their helical structures were unambiguously determined by X-ray crystallography. The photophysical (UV/visible and emission) and chiroptical properties of these compounds were investigated in various solvents. Despite their structural similarities, phosphine oxide showed a significantly better CPL response than phosphine, with a high dissymmetry factor for emission (|g_lum|=(1.3–1.9)×10⁻³) that can be attributed to structural changes in the interior of the helicene helix.     

Reaction of secondary phosphine oxides with acylacetylenes

Secondary phosphine oxides reacted with 1-alkanoyl-2-phenylacetylenes in chemoselective fashion under mild conditions (20°C, THF) in the absence of a catalyst (diphenylphosphine oxide) or in the presence of potassium hydroxide [bis(2-phenylethyl)phosphine oxide] to give 1-alkyl-1-diphenyl(or 2-phenylethyl)-phosphoryl-3-phenylprop-2-yn-1-ols in up to 96% yield. The reaction of diphenylphosphine oxide with 1-alkanoyl-2-phenylacetylenes in the system KOH-THF (20°C) afforded not only adducts at the carbonyl group but also products of double α,β-addition at the triple bond, 2,3-bis(diphenylphosphoryl)-3-phenylpropan-1-ones.     

Diastereoselective and intramolecular cycloadditions of asymmetric p-nitroso phosphine oxides

Benzyl phenyl P-nitroso phosphine oxide (5) reacts as an N-O heterodienophile with 1,3-cyclopentadiene to give the diastereomeric cycloadducts 6a,b in a ratio of 1.5:1 (6a:6b). The same reaction in the presence of tin tetrachloride produces 6a,b in a ratio of 2.9:1 (6a:6b). Cycloaddition of the structurally modified P-nitroso phosphine oxide (18) with 1,3-cyclopentadiene forms the diastereomeric cycloadducts 16a,b in a ratio of 3.1:1 (16a:16b). These results suggest the reactions of these P-nitroso phosphine oxides and 1,3-cyclopentadiene occur through a transition state where the heterodienophile adopts an s-cis conformation and approaches the diene in an exo fashion syn to the phenyl group. This model resembles those proposed for the cycloadditions of the structurally similar asymmetric vinyl phosphine oxides. Reaction of 18 with 1,3-cyclopentadiene in the presence of a Lewis acid produces cycloadducts 16a,b in a ratio of 7:1 (16a:16b), which approaches synthetic utility. Similar experiments show that 1,3-cyclohexadiene likely reacts with P-nitroso phosphine oxides through a different transition state, limiting current predictions regarding the diastereoselectivity of these reactions. The intramolecular cycloaddition of an asymmetric P-nitroso phosphine oxide (19) for the first time produces a unique phosphorus-containing heterocyclic compound (20).     

Study of Electron Donor–Acceptor Complex Formation of o-Chloranil With a Series of Phosphine Oxides and Tri- n-butyl Phosphate by the Absorption Spectrometric Method

Electron donor–acceptor (EDA) complex formation of o-chloranil with six different phosphine oxides and tri-n-butyl phosphate (TBP) has been studied in CCl ₄ solution by the UV-VIS absorption spectrophotometric technique. An absorption band due to a charge–transfer (CT) transition is observed in the visible region. Utilizing the CT transition energy, the electron affinity of o-chloranil in solution has been calculated. Degrees of charge transfer, and oscillator and transition dipole strengths have also been calculated for all of the investigated EDA complexes. Except for TBP, other phosphine oxides, viz., tri-n-octyl phosphine oxide, tri-n-butyl phosphine oxide, triphenyl phosphine, octyl(phenyl)-N,N-diisobutylcarbamoylphosphine oxide, octyl(phenyl)-N,N-dicyclohexylcarbamoylmethylphosphine oxide and octyl(phenyl)-N,N-diisopropylcarbamoylmethylphosphine oxide have been shown to form stable 1:1 EDA complexes with o-chloranil. The complex of TBP with o-chloranil decays slowly into a secondary product. Formation constants of the EDA complexes have been determined.     

The synthesis of a [2.2]paracyclophane-derived secondary phosphine oxide and a study of its reactivity

A planar chiral secondary phosphine oxide based on [2.2]paracyclophane was synthesized and its chemistry investigated; it was shown to be a competent pre-ligand in palladium(0)-mediated reactions, and displayed promising activity in gold(I)-catalysed cyclisations. The secondary phosphine oxide could be transformed into a collection of P-stereogenic tertiary phosphine oxides. These are rare examples of the planar chirality of [2.2]paracyclophane being combined with a P-stereogenic centre. Unfortunately, epimerisation of the phosphorus stereocentre during reduction limits the use of this chemistry.