Vibrational spectra of a ferrocenyl phosphine derivative chemisorbed on 3-aminopropylsilyl modified silica gel

Samples of silica gel dried at different temperatures, silica gel modified with 3-aminopropylsilyl (APS) and silica gel modified with APS and further with a ferrocenyl phosphine derivative were investigated by DRIFT, transmission FTIR and MicroRaman spectroscopy. The reaction between 3-aminopropyltrimethoxysilane (APTMS) and silica gel was mainly identified by the diminishing or vanishing intensity of the stretching band of the free OH groups in the silica gel. Further chemical reaction of the APS groups with a ferrocenyl phosphine derivative (suitable as ligand in homogeneous catalysis) was identified in the IR spectra by the appearance of the CN stretching band of the formed Schiff base, and diminishing intensity of the δ(NH₂) modes. According to the IR spectra the reaction of the ferrocenyl phosphine derivative with the APS-modified silica gel is almost quantitative. From the recorded IR and Raman spectra, conclusions concerning the substitution of APTMS methoxy groups during the chemisorption on silica gel were derived. Through deconvolution of the complex Raman band in the siloxy stretching region of the APS-modified silica gel, the newly formed siloxy bond was identified.     

Odorless Preparation of Thioglycosides and Thio‐Michael Adducts of Carbohydrate Derivatives

A general, odorless, one‐pot methodology has been developed for the preparation of 1,2‐trans‐thioglycosides and thio‐Michael addition products of carbohydrate derivatives through triphenyl phosphine‐mediated cleavage of disulfides and reaction of the thiolate formed in situ with glycosyl bromides and glycosyl conjugated alkenes.     

A Convenient and Selective Palladium‐Catalyzed Aerobic Oxidation of Alcohols

An efficient procedure for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with molecular oxygen under ambient conditions has been achieved. By applying catalytic amounts of Pd(OAc)₂ in the presence of tertiary phosphine oxides (O?PR₃) as ligands, a variety of substrates are selectively oxidized without formation of ester byproducts. Spectroscopic investigations and DFT calculations suggest stabilization of the active palladium(II) catalyst by phosphine oxide ligands.     

Efficient and green syntheses of novel γ-aminophosphonate and phosphine oxide derivatives

Two synthetic protocols leading to novel γ-aminophosphonate and phosphine oxide derivatives, by reductive amination of γ-phosphonylketones, are reported. The first method involved a two-step procedure. Imine intermediates were first isolated from the p-toluenesulfonic acid-catalyzed reaction of primary amines with γ-ketophosphonates and phosphine oxides, then reduced with NaBH₄ in refluxing ethanol. The second method consists of a one-pot procedure which includes the condensation of γ-ketophosphonates and phosphine oxides with primary amines, in the presence of molecular sieves, followed by reduction with NaBH₄. These methods offer significant advantages over prior reports, such as efficiency, generality, and good yields. Furthermore, they are green protocols avoiding hazardous hydrides and solvents.     

钯-膦-酸体系催化烯烃氢酯基化反应研究进展

烯烃氢酯基化反应是羰基合成领域的重要分支之一,长期以来一直备受关注。目前已发展了钯基、铑基、钴基、钌基等众多催化体系,其中钯-膦-酸催化体系因具有反应条件温和、底物普适性良好、催化性能优异等优点而得到最广泛、最深入的研究。因此,我们对均相、非均相的钯-膦-酸催化体系在烯烃氢酯基化反应中的研究应用进行了简要综述,并对催化机理、催化剂组成和性能进行讨论,最后指出稳定性高、可回收性好的非均相钯-膦-酸催化体系将是该领域的研究重点。     

Reactivities of mixed organozinc and mixed organocopper reagents. Part 13 Kinetic study for phosphine‐catalyzed acylation of alkylarylzincs and effect of residual group on the transfer rate of alkyl group

Kinetics of reactions of di‐n‐butylzinc, n‐Bu₂Zn, and mixed n‐butyl(substituted phenyl)zinc reagents and n‐Bu(functional group (FG)?C₆H₄)Zn with benzoyl chloride in the presence of tri‐n‐butylphosphine have been investigated. Reaction rates of transferable n‐butyl group have been determined in tetrahydrofuran at 0 °C to compare the transfer rate of n‐butyl group in homo and mixed diorganozincs. Rate law is consistent with a third‐order reaction, which is first order in diorganozinc, benzoyl chloride, and n‐Bu₃P, and a mechanism was proposed. The lower reaction rate of n‐BuPhZn than that of n‐Bu₂Zn and negative reaction constant in Hammett plot are in accordance with the carbanionic charge of transferable n‐butyl group in the acylation reaction. These findings support the hypothesis that the reaction rate of transferable group, R_T, changes depending upon the residual group, R_R, in R_RR_TZn reagents. Copyright © 2016 John Wiley & Sons, Ltd.     

Triruthenium clusters containing mono and bidentate phosphines: Synthesis,structure, thermal reactivity and fluxional behavior

The syntheses, structures and thermal reactions of [Ru₃(CO)₉{P(C₄H₃E)₃}(μ-dppe)] (2, E = S; 3, E = O; dppe = 1,2-bis(diphenylphosphino)ethane) are described. These triphosphine-substituted clusters can be easily obtained in high yield from the Me₃NO initiated room temperature reaction between [Ru₃(CO)₁₀(μ-dppe)] (1) and P(C₄H₃E)₃. Both clusters have been structurally characterized which reveals that the functionalized phosphine P(C₄H₃E)₃ is coordinated to the remote ruthenium atom using the phosphorus atom, while the NMR spectroscopic data indicate that both clusters are fluxional in solution mainly due to the ring-flipping process involving the dppe ligand which has been probed by VT NMR spectroscopy. Thermolysis of 2 at 66 °C affords 1 via P(C₄H₃S)₃ dissociation, whilst that of 3 under similar experimental conditions also furnishes the diruthenium σ,π-furyl complex [Ru₂(CO)₆(μ,η²-C₄H₃O){μ-P(C₄H₃O)₂] (4) in addition to 1.     

Platinum Indolylphosphine Fluorido and Polyfluorido Complexes: An Interplay between Cyclometallation,Fluoride Migration,and Hydrogen Bonding

The reaction of [PtCl₂(COD)] (COD=1,5-cyclooctadiene) with diisopropyl-2-(3-methyl)indolylphosphine (iPr₂P(C₉H₈N)) led to the formation of the platinum(ii ) chlorido complexes, cis-[PtCl₂{iPr₂P(C₉H₈N)}₂] ( 1 ) and trans-[PtCl₂{iPr₂P(C₉H₈N)}₂] ( 2 ). The cis-complex 1 reacted with NEt₃ yielding the complex cis-[PtCl{κ²-(P,N)-iPr₂P(C₉H₇N)}{iPr₂P(C₉H₈N)}] ( 3 ) bearing a cyclometalated κ²-(P,N)-phosphine ligand, while the isomer 2 with a trans-configuration did not show any reactivity towards NEt₃. Treatment of 1 or 3 with (CH₃)₄NF (TMAF) resulted in the formation of the twofold cyclometalated complex cis-[Pt{κ²-(P,N)-iPr₂P(C₉H₇N)}₂] ( 4 ). The molecular structures of the complexes 1–4 were determined by single-crystal X-ray diffraction. The fluorido complex cis-[PtF{κ²-(P,N)-iPr₂P(C₉H₇N)}{iPr₂P(C₉H₈N)}] ⋅ (HF)₄ ( 5 ⋅ (HF)₄) was formed when complex 4 was treated with different hydrogen fluoride sources. The Pt(ii ) fluorido complex 5 ⋅ (HF)₄ exhibits intramolecular hydrogen bonding in its outer coordination sphere between the fluorido ligand and the NH group of the 3-methylindolyl moiety. In contrast to its chlorido analogue 3 , complex 5 ⋅ (HF)₄ reacted with CO or the ynamide 1-(2-phenylethynyl)-2-pyrrolidinone to yield the complexes trans-[Pt(CO){κ²-(P,C)-iPr₂P(C₉H₇NCO)}{iPr₂P(C₉H₈N)}][F(HF)₄] ( 7 ) and a complex, which we suggest to be cis-[Pt{C=C(Ph)OCN(C₃H₆)}{κ²-(P,N)-iPr₂P(C₉H₇N)}{iPr₂P(C₉H₈N)}][F(HF)₄] ( 9 ), respectively. The structure of 9 was assigned on the basis of DFT calculations as well as NMR and IR data. Hydrogen bonding of HF and NH to fluoride was proven to be crucial for the existence of 7 and 9 .     

A Phosphine‐Catalyzed Novel Asymmetric [3+2] Cycloaddition of C,N‐Cyclic Azomethine Imines with δ‐Substituted Allenoates

Catalytic asymmetric [3+2] cycloadditions of C,N‐cyclic azomethine imines with δ‐substituted allenoates have been developed in the presence of (S)‐Me‐f‐KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo‐ and good enantioselectivities under mild condition. The substrate scope has been also examined. This is the first time that δ‐substituted allenoates have been applied as a δ,γ‐C?C bond participated C₂ synthon in asymmetric synthesis.     

Phosphine‐Catalyzed [3+2] Cycloaddition Reactions of Azomethine Imines with Electron‐Deficient Alkenes: A Facile Access to Dinitrogen‐Fused Heterocycles

An efficient method for the phosphine‐catalyzed [3+2] cycloaddition reaction of azomethine imines with diphenylsulfonyl alkenes to give dinitrogen‐fused bi‐ or tricyclic heterocyclic compounds in high yields has been described. Moreover, two phenylsulfonyl groups installed on the heterocyclic products could be conveniently removed or transformed to other functional groups, making the reaction more useful.