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1.
Dinuclear rhodium complexes of the type [Rh2(C2O4)(diolefin)2] (diolefin)2  1,5-cyclooctadiene, 2,5-norbornadiene and tetrafluorobenzobarrelene) with bridging oxalate ligands have been obtained by reaction of [Rh(acac)(diolefin)] with oxalic acid (2: 1 mol ratio). The use of a 1 : 1 molar ratio affords [Rh(HC2O4)(COD)], that reacts with [Ir(acac)(COD)] yielding the heterodinuclear [(COD)Rh(C2O4)Ir(COD)] complex. Treatment of [Rh2(C2O4)(diolefin)2] complexes with phenanthroline type ligands leads to ionic complexes of formula [Rh(diolefin) (phen)][Rh(C2O4)(diolefin)]. Bubbling of carbon monoxide through solutions of the diolefin complexes leads to the formation of carbonylrhodium species of formula [Rh2(C2O4)(CO)2L2] (L = CO, PPh3t-BuNC) or [Rh(CO)2(phen)] - [Rh(C2O4)(CO)2]. Other related malonate complexes are also described.  相似文献   

2.
The early-late heterometallic complexes [TiCp((OCH2)2Py)(μ-O)M(COD)] (M = Rh, Ir) behave as four-electron donor ligands yielding the polynuclear cationic complexes [TiCp(OCH2)2 Py(μ-O){M(COD)}2]OTf (M = Rh (1), Ir (2)). The molecular structure of complex 1 has been established through an X-ray diffraction study.  相似文献   

3.
Biphen(OPi-Pr) and (COD)PtCl2 give Biphen(OPi-Pr)PtCl2 which upon treating with ethyl Grignard forms Biphen(OPi-Pr)PtEt2. The thermal decomposition of Biphen(OPi-Pr)PtEt2 was investigated in the temperature range of 353-383 K. The clean and quantitative formation of the Pt(Ethene) adduct was observed. X-ray structures of a molecule in the solid state of all three reaction products and two further related complexes with phenyl fingers instead of i-Pr have been determined. For the complexes with i-Pr fingers a decisive deviation from a square plane is observed in contrast to the complexes with phenyl fingers. The P-Pt-P angle increases from about 95° in Biphen(OPi-Pr)PtCl2 to about 120° in Biphen(OPi-Pr)Pt(Ethene), forcing the bridging C-C single bond of the biphenyl fragment as near as 4.17 Å to the Pt center. No through-space coupling between the bridging C atoms and the Pt center could be observed in 13C NMR spectroscopy. No bond lengthening of the bridging C-C single bond in the biphenyl fragment was observed in Biphen(OPi-Pr)Pt(Ethene) in comparison to the precursor complexes. The thermal decomposition of Biphen(OPi-Pr)PtEt2 can be described by a first-order kinetic and the activation parameters were determined (temperature range: 353-383 K; ΔH = 173.8 ± 16.2 kJ/mol and ΔS = 104.7 ± 44.1 J/(mol K)). The reaction kinetics were also measured for perdeuterated ethyl groups yielding in a kinetic isotopic effect of 1.56 ± 0.14 which was almost temperature-independent. Selective deuteration at α and β position of the ethyl group, respectively, showed that β-H elimination takes place fast in comparison to the complete thermolysis. In the temperature range of 333-353 K only a scrambling of the deuterium atoms was found without further decomposition (temperature range: 333-353 K; ΔscramH = 76.1 ± 15.2 kJ/mol, ΔscramS = −80.7 ± 45.5 J/(mol K) for Biphen(OPi-Pr)PtEt2-d6). The ethene is not lost during the scrambling process. The scrambling process is connected with a primary KIE decisively larger than 1.56. Biphen(OPi-Pr)Pt(Ethene) exchanges the coordinated ethene with ethene in solution as proven by labeling experiments. Both a dissociative and an associative mechanism could be shown to take place as ethene exchange reaction by means of VT1H NMR spectroscopy via line shape analysis (temperature range: 333-373 K; ΔassH = 26.9 ± 29.6 kJ/mol, ΔassS = −148.0 ± 87.5 J/(mol K), ΔdissH = 86.0 ± 6.5 kJ/mol, ΔdissS = 5.4 ± 17.8 J/(mol K)). The Pt(0) complex formed during the dissociative loss of ethene activates several substrates among them: O2, H2, H2SiPh2 via Si-H activation, MeI presumably via forming a cationic methyl adduct and ethane via C-H activation but it was proven that the bridging C-C single bond of the biphenyl fragment is not even temporarily broken. The materials were characterized by means of 1H NMR, 13C NMR, 31P NMR, 195Pt NMR, EA, MS, IR, X-ray analysis and polarimetric measurement where necessary.  相似文献   

4.
Asymmetrical cyclic phosphite and phosphinite ligands of a novel type bearing either trifluoromethyl or pentafluorophenyl group were synthesized using >PCl or >PN< species and racemic fluorinated alcohols. The P-ligands were converted to complexes of RhIII(L)(Cp)Cl2 type (where L = phosphite or phosphinite) and, in two instances, their stereostructures were evaluated by X-ray analysis. These complexes along with in situ systems, formed from Rh(CO)2(acac) precursor and the corresponding ligand, were tested in the hydroformylation of styrene. Both systems provided excellent hydroformylation activities at 100 °C. Using the RhI in situ systems, moderate and high regioselectivities towards the branched aldehyde (2-phenyl-propanal) were obtained at 100 and 40 °C, respectively.  相似文献   

5.
The mechanism of the [(Cp*MCl2)2] (M=Rh, Ir)‐catalyzed oxidative annulation reaction of isoquinolones with alkynes was investigated in detail. In the first acetate‐assisted C? H‐activation process (cyclometalated step) and the subsequent mono‐alkyne insertion into the M? C bonds of the cyclometalated compounds, both Rh and Ir complexes participated well. However, the desired final products, dibenzo[a,g]quinolizin‐8‐one derivatives, were only formed in high yield when the Rh species participated in the final oxidative coupling of the C? N bond. Moreover, a RhI sandwich intermediate was isolated during this transformation. The iridium complexes were found to be inactive in the oxidative coupling processes. All of the relevant intermediates were fully characterized and determined by single‐crystal X‐ray diffraction analysis. Based on this mechanistic study, a RhIII→RhI→RhIII catalytic cycle was proposed for this reaction.  相似文献   

6.
Bridged and unbridged N-heterocyclic carbene (NHC) ligands are metalated with [Ir/Rh(COD)2Cl]2 to give rhodium(I/III) and iridium(I) mono- and biscarbene substituted complexes. All complexes were characterized by spectroscopy, in addition [Ir(COD)(NHC)2][Cl,I] [COD = 1,5-cyclooctadiene, NHC =  1,3-dimethyl- or 1,3-dicyclohexylimidazolin-2-ylidene] (1, 4), and the biscarbene chelate complexes 12 [(η4-1,5-cyclooctadiene)(1,1′-di-n-butyl-3,3′-ethylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] and 14 [(η4-1,5-cyclooctadiene)(1,1′-dimethyl-3,3′-o-xylylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] were characterized by single crystal X-ray analysis. The relative σ-donor/π-acceptor qualities of various NHC ligands were examined and classified in monosubstituted NHC-Rh and NHC-Ir dicarbonyl complexes by means of IR spectroscopy. For the first time, bis(carbene) substituted iridium complexes were used as catalysts in the synthesis of arylboronic acids starting from pinacolborane and arene derivatives.  相似文献   

7.
The full LaCo1−xRhxO3 solid solution was investigated utilizing structural, electrical transport, magnetic, and thermal conductivity characterization. Strong evidence for at least some conversion of Rh3+/Co3+ to Rh4+/Co2+ is found in both structural and electrical transport data. The crystal structure is that of a rhombohedrally distorted perovskite over the range 0.0≤x≤0.1. The common orthorhombic distortion of the perovskite structure is found over the range 0.2≤x≤1.0. A crossover of all three orthorhombic cell edges occurs at x=0.5 giving the appearance of a cubic structure, which actually remains orthorhombic. The octahedra in the orthorhombic structure must be distorted for x values less than 0.5, and the observed distortion suggests orbital ordering for Co2+. Electrical resistivity measurements as a function of temperature show semiconducting-like regions for all compositions. There is a steady increase in electrical resistivity as the Rh content increases. Large positive thermopower values are generally obtained above 475 K. With increasing Rh substitution there is a decrease in thermal conductivity, which slowly rises with increasing temperature due to increased electrical conductivity. The electronic part of the thermal conductivity is suppressed significantly upon Rh substitution. A thermoelectric figure-of-merit (ZT) of about 0.075 has been achieved for LaCo0.5Rh0.5O3 at 775 K, and is expected to reach 0.15 at 1000 K.  相似文献   

8.
The electrochemical reduction of the monocation of bis-(cyclo-octadiene)Rh[(COD)2Rh+] has been studied in chlorinated hydrocarbons and d6-acetone by cyclic voltammetry, chronoamperometry and exhaustive coulometry. Successive one-electron reductions are observed for the couples (COD)2Rh+/(COD)2Rh and (COD)2Rh/(COD)2Rh at -1.34 V vs. Fc and -1.93 V vs. Fc respectively. The 17-electron Rh(0) radical (COD)2Rh abstracts a Cl atom from CH2Cl2 to give the dinuclear complex [(COD)Rh(μ-Cl)]2 in high yield at 298 K. At subambient temperatures this reaction is suppressed and the dominant decomposition product is apparently (COD)Rh(C8H13), formed by H atom abstraction by (COD)2Rh from solvent and/or adventitious water. Electrolysis products were characterized by electron spin resonance (ESR), nuclear magnetic resonance (NMR) and mass spectrometry. The reactivity of the radical is rationalized by a bonding model in which the lowest unoccupied molecular orbital (LUMO) is dx2−y2 with some diolefin mixing. ESR measurements are consistent with this model and suggest that the COD ligands form a ligand field around Rh which is closer to square planar than to tetrahedral.  相似文献   

9.
The solid solution series Li2Ir1-xRhxO3 is synthesized for several values of x between 0 and 1. The compounds possess a monoclinic layered structure (space group C2/m) throughout the solid solution range with the lattice constants following Vegard's relationship. Magnetization and resistivity data below room temperature are presented. The effective magnetic moment (μeff) is reduced below the value obtained by interpolating between the end-members, presumably due to nearest neighbor charge exchange leading to non-magnetic Ir5+/Rh3+ pairs. Surprisingly, the degree of reduction of μeff cannot be explained by a random mixture of Ir and Rh and, in particular, is strongly asymmetric around x = 0.5. This anomalous moment reduction possibly results from the difference in on-site Coulomb repulsion between Ir and Rh ions.  相似文献   

10.
Two new quaternary delafossite type oxides with the general formula Ag(Li1/3M2/3)O2, M=Rh, Ir, have been synthesized, and their structures characterized. Based on X-ray and electron diffraction analyses the structural similarity with AgRhO2 delafossite, has been evidenced. The real structures of the quaternary delafossites have been revealed, which has allowed to fully explain the diffuse scattering as observed in X-ray powder diffraction. AgRhO2 is thermally stable up to 1173 K, the behavior of the two quaternary compounds AgLi1/3Rh2/3O2 and AgLi1/3Ir2/3O2 is comparable, and they decompose above 950 and 800 K, respectively. AgRhO2 shows temperature independent paramagnetism, while for the other two an effective magnetic moment of 1.77μB for Ir, and 1.70μB for Rh were determined, applying the Curie-Weiss law. All compounds are semiconducting with activation energies of 4.97 kJ mol−1 (AgLi1/3Rh2/3O2), 11.42 kJ mol−1 (AgLi1/3Ir2/3O2) and 17.58 kJ mol−1 (AgRhO2).  相似文献   

11.
The synthesis and characterization of a previously unknown, rare organometallic-phosphate complex, {[Bu4N][(1,5-COD)Ir · HPO4]}n (1), is described. Characterization of 1 was accomplished by elemental analysis, electrospray mass spectrometry (ES-MS), and 1H and 13C NMR which established the symmetry of the product as at least C2 or Cs. The ES-MS reveals an interesting, Ir(I) to Ir(III) oxidative process with intense peaks displaying the 191Ir/193Ir isotopic distribution patterns expected for the fragments [(1,5-COD)IrIII(HPO4)2], [(C8H11)2(IrIII)2(PO4)(HPO4)(H2O)], and [(C8H11)2(IrIII)2(PO4)(HPO4)(H2O)2]. These fragments, in turn, provide evidence for a structure with two HPO42− groups attached to a single Ir, for example ring structures (of at least such C2 or Cs symmetry) such as {[Bu4N][(1,5-COD)Ir · HPO4]}2. Complex 1 is significant since it is known to be the preferred, compositionally precise precursor to the prototype example of a recently discovered class of novel, HPO42− and Bu4N+ stabilized nanoclusters, (Bu4N)2n2n+[Ir(0)n · (HPO4)n]2n. Such nanoclusters are being extended, via their analogous hydrogenphosphate-organometallic precursors (1,5-COD)M+ or 2+/HPO42− (M=Rh(I), Ru(II), Pt(II)) to their corresponding, catalytically active [M(0)n · (HPO4)n]2n nanoclusters.  相似文献   

12.
The chemical kinetics, studied by UV/Vis, IR and NMR, of the oxidative addition of iodomethane to [Rh((C6H5)COCHCOR)(CO)(PPh3)], with R = (CH2)nCH3, n = 1-3, consists of three consecutive reaction steps that involves isomers of two distinctly different classes of RhIII-alkyl and two distinctly different classes of RhIII-acyl species. Kinetic studies on the first oxidative addition step of [Rh((C6H5)COCHCOR)(CO)(PPh3)] + CH3I to form [Rh((C6H5)COCHCOR)(CH3)(CO)(PPh3)(I)] revealed a second order oxidative addition rate constant approximately 500-600 times faster than that observed for the Monsanto catalyst [Rh(CO)2I2]. The reaction rate of the first oxidative addition step in chloroform was not influenced by the increasing alkyl chain length of the R group on the β-diketonato ligand: k1 = 0.0333 ([Rh((C6H5)COCHCO(CH2CH3))(CO)(PPh3)]), 0.0437 ([Rh((C6H5)COCHCO(CH2CH2CH3))(CO)(PPh3)]) and 0.0354 dmmol−1 s−1 ([Rh((C6H5)COCHCO(CH2CH2CH2CH3))(CO)(PPh3)]). The pKa and keto-enol equilibrium constant, Kc, of the β-diketones (C6H5)COCH2COR, along with apparent group electronegativities, χR of the R group of the β-diketones (C6H5)COCH2COR, give a measurement of the electron donating character of the coordinating β-diketonato ligand: (R, pKa, Kc, χR) = (CH3, 8.70, 12.1, 2.34), (CH2CH3, 9.33, 8.2, 2.31), (CH2CH2CH3, 9.23, 11.5, 2.41) and (CH2CH2CH2CH3, 9.33, 11.6, 2.22).  相似文献   

13.
A new cyclometalated ligand 1,3-dimethyl-5-phenyl-1H-[1,2,4]-triazole (pdt) was designed and synthesized. And the corresponding IrIII complex Ir(pdt)2(phen5f) (phen5f stands for 4,4,5,5,5-pentafluoro-1-(1′,10′-phenanthrolin-2′-yl)-pentane-1,3-dionate) was obtained. According to the measurement of the lowest triplet state energy level of Ir(pdt)2(phen5f), it is suitable for sensitizing NIR (near-infrared) lanthanide ions instead of EuIII. The bimetallic complex [(pdt)2Ir(μ-phen5f)YbCl2 · 2CH3CH2OH · H2O]Cl was synthesized by the approach of “complexes as ligands”. Data showed that the emission quenching was observed in the solid state when the IrIII–YbIII complex was compared with the IrIII complex, which implied that energy transfer might occur from IrIII complex-ligand to YbIII ion. Upon irradiation of the MLCT (metal-to-ligand charge transfer) absorption of Ir(pdt)2(phen5f), the characteristic emission of YbIII was obtained with the peak around 978 nm.  相似文献   

14.
Three platinum group elements (Pd, Ir and Rh) both in solution and in pre-reduced form, and also combined with Mg(NO3)2 or ascorbic acid, were assessed as possible chemical modifiers on the atomization of As in digest solutions of seafood matrices (clam and fish tissue) by tungsten coil electrothermal atomic absorption spectrometry (TCA-AAS) and compared without a modifier. Of 28 modifier alternatives in study including single form and binary mixtures, and based on maximum pyrolysis temperature without significant As loss and best As absorbance sensitivity during atomization, three modifiers: Rh (0.5 μg), Ir (1.0 μg) and Rh (0.5 μg) + ascorbic acid (0.5 μg), at optimum amounts were pre-selected and compared. The definitive modifier (rhodium (0.5 μg)) was selected by variance analysis. The mean within-day repeatability was 3% in consecutive measurements (25-300 μg l−1) (three cycles, each of n = 6) and showed good short-term stability of the absorbance measurements. The mean reproducibility was 4% (n = 18 in a 3-day period) and the detection limit (3σblank/slope) was 42 pg (n = 16). Quantitation was by standard additions to compensate for matrix effects not corrected by the modifier. Three sample digestion procedures were compared in fish and clam tissue samples: microwave acid digestion alone (A) or combined with the addition of 2% (m/v) K2S2O8 solution followed either by UV photo-oxidation (B) or re-digestion in a thermal block (C). The accuracy was established by determination of As in certified reference material of dogfish muscle (DORM-2). Procedures B and C showed good recoveries (102% (n = 4) and 103% (n = 7), respectively), whereas procedure A was not quantitative (85%). The methodology is simple, fast, reliable, of low cost and was applied to the determination of total As in lyophilized samples of clam and fish collected in the Chilean coast.  相似文献   

15.
Coordination chemistry of a new pyridine imidazole-2-ylidene ligand (pyNC) system with sterically hindered substituents toward rhodium(I) metal ions has been investigated. The rhodium complex [(pyNC)RhCl(COD)] (COD = 1,5-cyclooctadiene) was prepared via the transmetallation from the silver complex [(C-pyNC)2Ag]AgI2. Upon the abstraction of chloride, the pyridinyl nitrogen coordinated to the metal center and formed [(C,N-pyNC)Rh(COD)]BF4 with the chelation of pyNC. The pyridinyl nitrogen donor was found to be labile and could be replaced by various donors such as phosphine, azide and halides. Substitution of COD by various donors does not proceed except strong π-acid ligands such as CO and P(OCH3)3. However, the chelation of pyNC was replaced by the bisphosphine (P∼P) to form [(P∼P)2Rh]BF4, which was subsequently oxidized to yield [(P∼P)2Rh(O2)]BF4.  相似文献   

16.
Two dinuclear RhI-cyclooctadiene complexes [1,4-(cod)Rh(B(R’)pz2)-C6H4-(B(R’)pz2)Rh(cod)], linked by a ditopic scorpionate ligand, have been prepared and fully characterized (R′ = Ph (2), C6F5 (2F); pz = pyrazolide). Both compounds were tested as catalysts for phenylacetylene polymerization but showed no catalytic activity. Attempts at the synthesis of corresponding complexes of the sterically more demanding ligands (R′ = Ph (4), C6F5 (4F); pzPh = 3-phenylpyrazolide) resulted in B-N bond cleavage and formation of the dinuclear complex [(cod)Rh(μ-pzPh)2Rh(cod)] (5). Complex 5 proved to be an efficient catalyst for the preparation of highly stereoregular head-to-tail cis-transoidal poly(phenylacetylene).  相似文献   

17.
The synthesis of novel N-acetyl-N,N-dipyrid-2-yl complexes of RhI and IrI, i.e. [RhCl(CH3CONPy2)(COD)] (1) and [IrCl(CH3CONPy2)(COD)] (2), respectively, is described. Upon prolonged treatment in CH2Cl2 at room temperature, complex 1 is transformed into a cationic Rh-complex, i.e. [Rh(CH3CONPy2)(COD)+RhCl2(COD)] (1a). Compound 1a crystallizes in the monoclinic space group P21/c, complex 2 crystallizes in the triclinic space group . Compound 1 was investigated for its catalytic activity in the hydroformylation of cyclooctene as well as of 1-octene. In addition, 1 was used in various carbonyl hydrosilylation reactions of both aldehydes and ketones. There, turn-over numbers up to 50 000 and yields in the range of 85-100% were observed. Finally, compound 1 was successfully used for the polymerization of N2CHCOOEt yielding highly stereoregular poly(ethoxycarbonylcarbene) with Mw = 67 000 g/mol and a polydispersity index (PDI) of 2.59.  相似文献   

18.
Organometallic dithiolene complexes, which were formulated as [Cp*M(dcbdt)] and [Cp*M(dcdmp)] (M = Co, Rh, Ir; Cp* = η5-pentamethylcyclopentadienyl, dcbdt = 4,5-dicyanobenzene-1,2-dithiolate, dcdmp = 2,3-dicyano-5,6-dimercaptopyrazine) were prepared from a low valent Cp*CoI or high valent Cp*MIII species (MIII = CoIII, RhIII, IrIII). The UV-Vis absorption spectral and electrochemical data of them were obtained. The lowest absorption (HOMO-LUMO) energies of them became redshift in order of the Co > Rh > Ir complexes. The reduction potentials suggested that the central metal modifies their LUMO levels. The molecular and crystal structures of [Cp*Co(dcbdt)] (3a), [Cp*Co(dcdmp)] (4a) and [Cp*Rh(dcdmp)] (4b) were determined by X-ray diffraction studies. The cobalt complexes 3a and 4a were monomeric, formally 16-electron complexes and have two-legged piano-stool geometries. The crystal structure of 3a indicated some plane-to-plane intermolecular interactions such as benzene?benzene interaction on the dcbdt ligand and two Cp*?benzene π-π stackings. 4a showed plane-to-plane interaction with a pseudo-4-fold-symmetry arrangement between the pyrazine moieties on the dcdmp ligand. The rhodium complex 4b was dimeric in the crystal to form a criss-cross arrangement and had a three-legged piano-stool geometry, but it was monomerized in solution. The dimer of 3b was observed in the oxidation process of the cyclic voltammogram.  相似文献   

19.
Single crystals of the oxidephosphates TiIIITiIV3O3(PO4)3 (black), CrIII4TiIV27O24(PO4)24 (red-brown, transparent), and FeIII4TiIV27O24(PO4)24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [TiIIITiIV3O3(PO4)3: Z=24, a=7.3261(9) Å, b=22.166(5) Å, c=39.239(8) Å, R1=0.029, wR2=0.084, 6055 independent reflections, 301 variables; CrIII4TiIV27O24(PO4)24: Z=1, a=7.419(3) Å, b=21.640(5) Å, c=13.057(4) Å, R1=0.037, wR2=0.097, 1524 independent reflections, 111 variables; FeIII4TiIV27O24(PO4)24: Z=1, a=7.4001(9) Å, b=21.7503(2) Å, c=12.775(3) Å, R1=0.049, wR2=0.140, 1240 independent reflections, 112 variables). For TiIIITiIVO3(PO4)3 a well-ordered structure built from dimers [TiIII,IV2O9] and [TiIV,IV2O9] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr4Ti27O24(PO4)24 and Fe4Ti27O24(PO4)24, consisting of dimers [MIIITiIVO9] and [TiIV,IV2O9], monomeric [TiIVO6] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs TiIII4TiIV27O24(PO4)24 (a=7.418(2) Å, b=21.933(6) Å, c=12.948(7) Å) is isotypic to the oxidephosphates MIII4TiIV27O24(PO4)24 (MIII: Cr, Fe). The UV/vis spectrum of Cr4Ti27O24(PO4)24 reveals a rather small ligand-field splitting Δo=14,370 cm−1 and a very low nephelauxetic ratio β=0.72 for the chromophores [CrIIIO6] within the dimers [CrIIITiIVO9].  相似文献   

20.
The addition of silver salts had an effect on the catalyst activity in the Pd(0)-catalyzed cyclization-coupling tandem reaction, as well as in the Rh(I)-catalyzed Pauson-Khand reaction. The cationic palladium complex generated from Pd(PPh3)4 (2.5 mol%) with AgSbF6 (1.5 equiv.) activates the triple bond of 2,2-difluoropropargylic amides to give the 4,5-disubstituted 3,3-difluoro-γ-lactams, through a sequential 5-endo-dig cyclization and cross-coupling reaction. The γ-lactam was transformed into ring-opened monofluorovinylic compounds after silica-gel chromatography. Pauson-Khand reaction of fluorinated 1,7-enyne amides using catalytic amounts of [Rh(COD)2]2 (5 mol%) and AgOTf (20 mol%) gave the corresponding gem-difluorinated bicyclic lactam.  相似文献   

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