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1.
Hide-Ki Ishida Hideharu Ishida Makoto Kiso Akira Hasegawa 《Tetrahedron: Asymmetry》1994,5(12):2493-2512
The first total synthesis of ganglio-series gangliosides GQ1b, GT1b and GD1b, which contain α-sialyl-(2→8)-α-sialic acid residue in the structure, will be described. Glycosylation of 2-(trimethylsilyl)ethyl O-(2-acetamido-6-O-benzyl-2-deoxy-3,4-O-iso-propylidene-β-
-galactopyranosyl)-(1→4)-O-(2,6-di-O-benzyl-β-
-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (7) with methyl [phenyl 5-acetamido-8-O-(5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-
-glycero-α-
-galacto-2-nonulopyranosylono-1′,9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-2-thio-
-glycero-
-galacto-2-nonulopyranosid]onate (8) using N-iodosuccinimide (NIS)-trifluoromethanesulfonic acid (TfOH) in acetonitrile gave the protected GD2 pentasaccharide 9, which was converted into the pentasaccharide acceptor 10 by de-O-isopropylidenation. Glycosylation of 10 with methyl thioglycoside derivatives 18, 26, 34 by use of dimethyl(methylthio)sulfonium triflate (DMTST) gave the protected ganglioside oligosaccharides 19, 27 and 35, respectively. Compounds 9, 19, 27 and 35 were transformed into the corresponding α-trichloroacetimidates 13, 22, 30 and 38, via reductive removal of benzyl groups, O-acetylation, selective removal of 2-(trimethylsilyl)ethyl group, and treatment of trichloroacetonitrile. Condensation of the imidates 13, 22, 30 and 38 with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (14) gave the corresponding β-glycosides 15, 23, 31 and 39, which were converted, via selective reduction of azido group, coupling with octadecanoic acid, de-O-acylation, and saponification of methyl esters and lactone groups, into the corresponding gangliosides GD2 (17), GD1b (25), GT1b (33) and GQ1b (41). 相似文献
2.
Junes Ipaktschi Katja Reimann Michael Serafin Ansgar Dülmer 《Journal of organometallic chemistry》2003,670(1-2):66
Treatment of the η1-acetylide complex [(η5-C5H5)(CO)(NO)W---CC---C(CH3)3]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH3)3, C6H5, Si(CH3)3, 6a–6c] or n-C4H9Li and protonation with H2O, afforded the corresponding oxametallacyclopentadienyl complexes (η5-C5H5)W(I)(NO)[η2-O=C(CC---R)CH=CC(CH3)3] (7a–7c), 8c and (η5-C5H5)W(I)(NO)[η2-O=C(n-C4H9)CH=CC(CH3)3] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η5-C5H5)(I)(CO)(NO)W---CC---C(CH3)3] (5). Subsequent nucleophilic addition of Li---CC---R 6a–6c or n-C4H9Li and a reductive elimination step followed by protonation leads to the products 7a–7c and 9. One reaction intermediate could be trapped with CF3SO3CH3 and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine. 相似文献
3.
Kota Thirumala Prasad Gajendra Gupta Anna Venkateswara Rao Babulal Das Kollipara Mohan Rao 《Polyhedron》2009,28(13):2649-2654
The mononuclear complexes [(η6-arene)Ru(ata)Cl]PF6 {ata = 2-acetylthiazole azine; arene = C6H6 [(1)PF6]; p-iPrC6H4Me [(2)PF6]; C6Me6 [(3)PF6]}, [(η5-C5Me5)M(ata)]PF6 {M = Rh [(4)PF6]; Ir [(5)PF6]} and [(η5-Cp)Ru(PPh3)2Cl] {η5-Cp = η5-C5H5 [(6)PF6]; η5-C5Me5 (Cp*) [(7)PF6]; η5-C9H7 (indenyl); [(8)PF6]} have been synthesised from the reaction of 2-acetylthiazole azine (ata) and the corresponding dimers [(η6-arene)Ru(μ-Cl)Cl]2, [(η5-C5Me5)M(μ-Cl)Cl]2, and [(η5-Cp)Ru(PPh3)2Cl], respectively. In addition to these complexes a hydrolysed product (9)PF6, was isolated from complex (4)PF6 in the process of crystallization. All these complexes are isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV–Vis spectroscopy. The molecular structures of [2]PF6 and [9]PF6 have been established by single-crystal X-ray structure analyses. 相似文献
4.
Zia-ur-Rehman Niaz Muhammad Shaukat Shuja Saqib Ali Ian S. Butler Auke Meetsma Momin Khan 《Polyhedron》2009,28(16):3439-3448
Some new tri-, chlorodi- and diorganotin(IV) dithiocarboxylates (1–10) of 4-benzylpiperidine-1-carbodithioate ligand (L), with general formulae R3SnL {R = n-C4H9 (1), C6H11 (2), CH3 (3) and C6H5 (4)}, R2SnClL {R = n-C4H9 (5), C2H5 (7), CH3 (9)} and R2SnL2 {R = n-C4H9 (6), C2H5 (8), CH3 (10)}, have been synthesized by the reaction of organotin(IV) chlorides with the ligand-salt in the appropriate molar ratio. Elemental analysis, Raman, IR, multinuclear NMR (1H, 13C and 119Sn) and X-ray crystallographic studies have been undertaken to elucidate the structures of the complexes, both in solution and in solid state. Single-crystal X-ray diffraction study indicate trimeric, dimeric, supramolecular cyclic and supramolecular zig–zag chain structures for complexes 2, 4, 6 and 9, respectively. Square-pyramidal geometry is attributed to complex 9 on the basis of the τ value (0.4). A subsequent antimicrobial study indicates that the compounds are biologically active. 相似文献
5.
Matthias Bierenstiel Magdalena Dymarska Ebbing de Jong Marcel Schlaf 《Journal of molecular catalysis. A, Chemical》2008,290(1-2):1-14
The 16 electron ruthenium complexes [(η6-1-isopropyl-4-methyl-benzene)(X-N)Ru(II)], where X-N is 2-amido-1-ethoxide (2), 1-N-p-tosyl-1,2-diamido-ethane (3), 1-N-p-tosyl-1,2-diamido-benzene (7), 1-N-(p-tosyl)-1,2-diamido-1,1,2,2-tetramethyl-ethane (8) and 1-N-(p-tosyl)-1,2-diamido-meso-1,2-diphenyl-ethane (9) have been evaluated as catalysts for the transfer dehydrogenation of secondary alcohols to ketones in acetone and/or cyclohexanone solvent. Complexes 2 and 3 cannot be isolated and decompose under these conditions. In contrast complexes 7, 8 and 9 are supported by ligands designed to resist β-hydride elimination and can with the exclusion of oxygen be held in solution for weeks. Complex 7 is not active as a catalyst. Complexes 8 and 9 are highly air-sensitive and active as catalysts for transfer (de)hydrogenations under oxidizing and reducing conditions, respectively. There is no coordinative inhibition of the catalysts by the ketone solvent under oxidizing conditions, but both catalysts show a correlation between the reaction rates and the ΔG values of the reactions with reactions leading to α, β-unsaturated ketones proceeding faster. For all alcohol/ketone substrate pairs where the ketone is not α, β-unsaturated, the hydrogenation reactions under reducing conditions (iso-propanol solvent) are at least one order of magnitude faster than the corresponding dehydrogenation reaction under oxidizing conditions (acetone solvent). 相似文献
6.
Xiao Guang Ma Hai Feng Tang Chang Hai Zhao Ning Ma Min Na Yao Ai Dong Wen 《中国化学快报》2009,20(10):1227-1230
Two new 24-hydroxylated asterosaponins,sodium(20R,24S)-6α-O-(4-O-sodiumsulfato-β-D-quinovopyranosyl)-5α-cholest-9(11)-en-3β,24-diol 3-sulfate(1) and sodium(20R,24S)-6α-O-[3-O-methyl-β-D-quinovopyranosyl-(1→2)-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl]-5α-cholest-9(11)-en-3β,24-diol 3-sulfate(2),were isolated from the starfish Culcita novaeguineae.Their structures were elucidated by extensive spectral analysis and chemical evidences. 相似文献
7.
The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH2) and Co(NO3)2 or Ni(NO3)2 in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H2O)2 (1) and Ni(pydc)(H2O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å3, Z=4; 2, monoclinic, P21/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å3, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO4N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated. 相似文献
8.
Michael J. McGeary Kirsten Folting William E. Streib John C. Huffman Kenneth G. Caulton 《Polyhedron》1991,10(23-24)
Lithium and potassium silyloxide complexes [Li(OSiPh3)]n (1), [K(thf)0.2 (OSiPh3)]n (3) and [K(OSiMe2tBu)]n (6) were prepared by deprotonation of HOSiPh3 or HOSiMe2tBu with [Li(nBu)] in hexane or KH in THF, respectively. Crystalline DME adducts [Li(μ-OSiPh3)(η2-DME)]2 (2) and [K4(μ3-OSiPh3)3(μ3-OSiPh2(η1-Ph))(η2-DME)]2 (μ-DME) (4) were prepared by dissolving 1 or 3, respectively, in dimethoxyethane followed by precipitation with alkane. The potassium-sequestered complexes [K(18-crown-6) (OSiPh3)]2 (5) and [K(18-crown-6)(OSiMe2tBu)]n (7) were prepared from 3 or 5, respectively, and one equiv. of 18-crown-6 ether. The complexes were characterized by single-crystal X-ray diffraction: [Li(μ-OSiPh3)(η2-DME)]2 (2): a dimer featuring tetrahedral lithium centres linked by bridging —OSiPh3 ligands. [Crystal data ( − 156°C): space group P
, a = 14.238(6), b = 15.182(7), c = 11.796(5) Å, α = 110.57(2), β = 112.02(2), γ = 63.02(1) Å, V = 2055.33 Å3, Z = 2.] [K4(μ3-OSiPh3)3{μ3-OSiPh2(η1-Ph)}(η2-DME)]2(μ-DME) (4): (1) two cubanes each having every potassium vertex chemically distinct; (2) one chelating DME ligand, one DME ligand bridging between two cubanes; and (3) a K-ipso-phenyl carbon contact. [Crystal data ( − 133°C): a = 14.246(4), b = 30.939(9), c = 17.981(5) Å, β = 112.33(1)° with Z = 2 in space group P21/c.] [K(18-crown-6)OSiPh3]2 (5): A dimer with slipped face-to-face stacking of the quasi-planar K(18-crown-6)+ part of the two Ph3SiOK(18-crown-6) molecules; these are linked by a dative bond from one ether oxygen of a given crown to potassium contained in the other crown. [Crystal data ( − 155°C): a = 9.324(2), b = 17.640(5), c = 18.148(15) Å, β = 91.60(1)° with Z = 4 in space group P21/c.] 相似文献
9.
Arlette Solladi-Cavallo Loïc Jierry Arlette Klein Michel Schmitt Richard Welter 《Tetrahedron: Asymmetry》2004,15(24):201
Three rigid monofluorinated trans-decalones 4a, 5e, and 6e (90% ee) have been synthesized from commercially available (−)-(R)-methyl naphthalenone (90% ee). Their structures have been fully characterized (NMR, X-ray): ketones 4a and 5e are Me,F-disubstituted α to the carbonyl with the fluorine axial and equatorial, respectively, while ketone 6e is F-monosubstituted α to the carbonyl with the fluorine equatorial. The use of these ketones as chiral catalysts for the epoxidation of trans-olefins (such as stilbene, β-methylstyrene and p-methoxy cinnamate) through the formation of dioxiranes shows (i) that dioxiranes with an equatorial fluorine α to the dioxirane ring are less reactive and provide lower ee’s than dioxiranes with an axial fluorine and having the same chirality and (ii) that an axial methyl α to the dioxirane ring is significantly less efficient than a fluorine. The results corroborate Armstrong and Houk’s theoretical model and our first hypothesis to rationalize the inverted enantioselectivities observed using α-fluorinated cyclohexanones having the same chirality, i.e.: rapid ring inversion (Curtin–Hammett principle) allows the dioxirane conformation to have the fluorine axial (even if less populated than the other) to contribute significantly to the epoxidation reaction. 相似文献
10.
Alshimaa A. Massoud Ahmed Hefnawy Vratislav Langer Mohamed A. Khatab Lars
hrstrom Morsy A.M. Abu-Youssef 《Polyhedron》2009,28(13):2794-2802
Two new silver(I) pyrazine complexes [Ag2(ampyz)(NO3)2]n, 1 and {[Ag(2,3-pyzdic)](NO3)}n, 2 (where ampyz = aminopyrazine, and 2,3-pyzdic = 2,3-pyrazinedicarboxamide) were synthesized and structurally characterized by X-ray single crystal structure analysis. Complex 1 has a 2D sheet structure through both bridging μO,O′-(NO3) groups and μN,N′-pyrazine moieties. A 3D structure with a characteristic (10,3)-d or 103-utp net is formed through extensive hydrogen bonding. Complex 2 has a 1D chain structure through bridging μN,N′-pyrazine moieties. Strong hydrogen bonds further connect these chains to extend the dimensionality to a 3D network structure. The complexes were tested as corrosion inhibitors for mild steel in 0.1 M nitric acid medium using potentiodynamic polarization technique. Both complexes are of mixed type corrosion inhibitors with dominant anodic effect. The inhibition efficiencies are 68% and 50% for complexes 1 and 2, respectively. The inhibition mechanisms of both inhibitors are mainly due to adsorption of the inhibitor molecules on the surface of mild steel. All data were compared and fitted to the kinetic-thermodynamic model. The binding constants K are 3263 and 1147 for complexes 1 and 2, respectively. 相似文献
11.
Ru-Fen Zhang Qing-Feng Wang Ming-Qing Yang Yue-Rong Wang Chun-Lin Ma 《Polyhedron》2008,27(14):3123-3131
Five new diorganotin(IV) complexes of the types {(Me2Sn)2[μ4-(C8H3NO6)](μ3-O)}n (1), {(Me2Sn)2[μ3-(C8H8O4)](μ3-O)}n (2), {(Me2Sn)2[μ4-(C8H10O4)](μ3-O)}n (3) {(Me2Sn)2[μ4-(C8H10O4)](μ3-O)}n (4) and {(Me2Sn)2[μ4-(C10H14O4)](μ3-O)}n (5) have been synthesized by reactions of 5-nitroisophthalic acid, meso-cis-4-cyclohexene-1,2-dicarboxylic, meso-cis-1,4-cyclohexanedicarboxylic acid, meso-cis-1,3-cyclohexanedicarboxylic acid and chiral cis-(1R,3S)-(+)-camphoric acid with trimethyltin chloride under hydrothermal condition. All complexes were characterized by elemental analysis, IR, 1H NMR, 13C NMR, 119Sn NMR and X-ray crystallography. The structural analyses show that complex 1 has a 1D infinite polymeric chain in which 5-nitroisophthalic acid acts as a tetradentate ligand coordinating to dimethyltin(IV) ions, complexes 2, 3 and 4 possess 2D polymeric structures in which dicarboxylate acid act as tridentate or tetradentate ligands coordinating to dimethyltin(IV) ions, complex 5 possesses a irregular 3D framework in which chiral cis-(1R,3S)-(+)-camphoric acid acts as a tetradentate ligand coordinating to dimethyltin(IV) ions. 相似文献
12.
Jos Alvano Prez-Bautista Martha Sosa-Rivadeneyra Leticia Quintero Herbert Hpfl Farid Andrs Tejeda-Dominguez Fernando Sartillo-Piscil 《Tetrahedron letters》2009,50(40):5572-5574
A practical and enantiopure synthesis for the preparation of key intermediates of conformationally locked γ-amino acid and nucleoside analogues is described. First, a highly stereoselective aziridine ring-opening reaction with phenylselenide anion was employed for the stereoselective synthesis of the chiral aminoselenide (1S,2S,1′S)-8, which after N-benzylation was transformed into the corresponding allyl amine (1S,1′S)-7 by oxidation with H2O2. Then, dihydroxylation–dehomologation of (1S,1′S)-7 with (OsO4/NMO, NaIO4) selectively afforded the desired γ-aminocyclopentene aldehyde (S)-1 and its corresponding γ-amino acid (S)-2 via an intramolecular selective aldol-condensation catalyzed by an internal base. 相似文献
13.
Vjera M. Pejanovic Julijana A. Petrovt Jnos J. Csandi Slobodanka M. Stankovi Duan A. Miljkovic 《Tetrahedron》1995,51(48)
Sodium borohydride reduction of anti-3-methoxy-17β-hydroxyestra-1,3,5(10)-trien-6,7-dione 7-oxime (4a) afforded syn-3-methoxy-6α,17β-dihydroxyestra-1,3,5(10)-trien-7-one oxime (5), which in thionyl chloride at −18 °C undenvent Beckmann fragmentation reaction to the unexpected 3-methoxy-6-oxo-17β-hydroxy-6.7-secoestra-1.3.5(10)-trien-7-nitrile (6). A mechanism of this fragmentation process was proposed. 相似文献
14.
Athanassios C. Tsipis Constantinos A. Tsipis Vicky Valla 《Journal of Molecular Structure》2003,630(1-3):81-100
A detailed exploration of the configurational and conformational space of glycolic acid and their conjugate bases has been carried out with the aid of first principles quantum chemical techniques at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p) levels of theory. The most stable configuration among the eight possible glycolic acid conformers corresponds to the E-s-cis, s-trans configuration, while the highest energy E-s-trans, s-cis conformer was found at 10.88 and 12.17 kcal mol−1 higher in energy at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p) levels of theory, respectively. Upon dissociation of glycolic acid the s-cis(syn), and s-trans(anti) configurations of the glycolate anion can be formed. The anti conformer was found to be less stable than the syn one by 14.20 and 16.87 kcal mol−1 at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p)) levels of theory, respectively. The computed B3LYP/6-311+G(d,p) proton affinity of the syn conformer for the protonation process affording the more stable E-s-cis, s-trans conformer, in vacuum was found to be 325.35 kcal mol−1 (ΔG0 value). From a methodological point of view, our results confirm the reliability of the integrated computational tool formed by the B3LYP density functional model. This model has subsequently been used to investigate the interaction of Ca2+ ions with the glycolic acid conformers and their conjugate bases in vacuum and in the presence of extra water ligands. For the complexes of glycolic acid conformers the η2–O,O–(COOH) coordination, that is the structure that arises from the coordination of the Ca2+ to the carboxylic group, is the global minimum of the PES, while the η2–O(OH),O–(COOH) coordination is a local minimum found at only 1.0 and 1.3 kcal mol−1 higher in energy at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p) levels of theory, respectively. Moreover, the two isomers exhibit nearly the same binding affinities, which are predicted to be 89 and 85 kcal mol−1 at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p) levels of theory, respectively. The same holds also true for the complexes of the glycolate anion. The η2–O,O–(COO−) coordination involving the syn conformer of the glycolato ligand, is the global minimum, while the η2–O(OH),O–(COO−) one lies at 1.5 and 5.6 kcal mol−1 higher in energy at the B3LYP/6-311+G(d,p) and CCSD(T)/6-31G(d,p) levels of theory, respectively. The other conformer with an η2–O,O–(COO−) coordination involving the anti conformer of the glycolato ligand, is less stable by only 0.2 kcal mol−1 at both levels of theory. Noteworthy is the trend seen for the incremental binding energy due to the successive addition of water molecules to [HOCH2C(O)O]Ca2+ species; the computed values are 30.4, 26.8, 22.9 and 16.2 kcal mol−1 at the B3LYP/6-311+G(d,p) level of theory for the mono-, di-, tri- and tetraaqua complexes, respectively. This trend arising from the repulsion of the dipoles between the water ligands and from unfavorable many body interactions is in accordance with those anticipated from electrostatic considerations. The Ca(II)-water interaction weakens with increasing coordination of the metal. Obviously, it is the electrostatic nature of the Ca(II)-water interactions that accounts well for the computed coordination geometries of the cationic (aqua)(glycolato)calcium complexes. Calculated structures, relative stability and bonding properties of the conformers and their complexes with [Ca(OH2)n]2+ (n=0–4) ions are discussed with respect to computed electronic and spectroscopic properties, such as charge density distribution, harmonic vibrational frequencies and NMR chemical shifts. 相似文献
15.
Alberto Fernndez Patricia Uría Jesús J. Fernndez Margarita Lpez-Torres Antonio Surez Digna Vzquez-García Ma Teresa Pereira Jos M. Vila 《Journal of organometallic chemistry》2001,620(1-2):8-19
Treatment of N-(2-chlorobenzylidene)-N,N-dimethyl-1,3-propanediamine (1) and N-(2-bromo-3,4-(MeO)2-benzylidene)-N,N-dimethyl-1,3-propanediamine (20) with tris(dibenzylideneacetone)dipalladium(0) in toluene gave the mononuclear cyclometallated complexes [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(Cl)] (2) and [Pd{3,4-(MeO)2C6H2C(H)=NCH2CH2CH2NMe2}(Br)] (21), respectively, via oxidative addition reaction with the ligand as a C,N,N terdentate ligand. Reaction of 2 with sodium bromide or iodide in an acetone–water mixture gave the cyclometallated analogues of 2, [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(Br)] (3) and [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(I)] (4), by halogen exchange. The X-ray crystal structures of 2, 3 and 4 were determined and discussed. Treatment of 2, 3, 4 and 21 with tertiary monophosphines in acetone gave the mononuclear cyclometallated complexes [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(L)(X)] (6: L=PPh3, X=Cl; 7: L=PPh3, X=Br; 8: L=PPh3, X=I; 9: L=PMePh2, X=Cl; 10: L=PMe2Ph, X=Cl) and [Pd{3,4-(MeO)2C6H2C(H)=NCH2CH2CH2NMe2}(L)(Br)] (22: L=PPh3; 23: L=PMePh2; 24: L=PMe2Ph). A fluxional behaviour due to an uncoordinated CH2CH2CH2NMe2 could be determined by variable temperature NMR spectroscopy. Treatment of 2, 3 and 4 with silver trifluoromethanesulfonate followed by reaction with triphenylphosphine gave the mononuclear complex [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(PPh3)][F3CSO3] (11) where the Pd–NMe2 bond was retained. Reaction of 2, 3 and 4 with ditertiary diphosphines in a cyclometallated complex–diphosphine 2:1 molar ratio gave the binuclear complexes [{Pd[C6H4C(H)=NCH2CH2CH2NMe2](X)}2(μ-L–L)][L–L=PPh2(CH2)4PPh2(dppb) (13, X=Cl; 14, X=Br; 15, X=I; L–L=PPh2(CH2)5PPh2(dpppe): 16, X=Cl; 17, X=Br; 18, X=I) with palladium–NMe2 bond cleavage. Treatment of 2, 3 and 4 with ditertiary diphosphines, in a cyclometallated complex–diphosphine 2:1, molar ratio and AgSO3CF3 gave the binuclear cyclometallated complexes [{Pd[C6H4C(H)=NCH2CH2CH2NMe2]}2(μ-L–L)][F3CSO3]2 (11: L–L=PPh2(CH2)4PPh2(dppb), X=Cl; 12: L–L=PPh2(CH2)5PPh2 (dpppe), X=Cl). Reaction of 2 with the ditertiary diphosphine cis-dppe in a cyclometallated complex–diphosphine 1:1 molar ratio followed by treatment with sodium perchlorate gave the mononuclear cyclometallated complex [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(cis-PPh2CH=CHPPh2–P,P)][ClO4] (19). 相似文献
16.
Stefan Kcher Bernhard Walfort Allison M. Mills Anthony L. Spek Gerard P.M. van Klink Gerard van Koten Heinrich Lang 《Journal of organometallic chemistry》2008,693(11):1991-1996
Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C6H2(CH2NMe2)2-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C6H2(CH2NMe2)2-2,6]−) are accessible by the reaction of Br-1-NC-4-C6H2(CH2NMe2)2-2,6 (2b) with [Pd2(dba)3 · CHCl3] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)2(SEt2)]2 (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C6H2(CH2NMe2)2-2,6)](ClO4)}n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe3)2}AgOClO3 (7) ([Ti] = (η5-C5H4SiMe3)2Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d8-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me2NCH2, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M. 相似文献
17.
Andrew M. McDonagh Marie P. Cifuentes Mark G. Humphrey Stephan Houbrechts Joachim Maes Andr Persoons Marek Samoc Barry Luther-Davies 《Journal of organometallic chemistry》2000,610(1-2)
The preparation of the chloro complex trans-[FeCl2{(R,R)-diph}2] (1) and the alkynyl complexes trans-[M(4-CCC6H4R)Cl{(R,R)-diph}2] [M=Fe, R=NO2 (2); M=Ru, R=H (4), NO2 (5), (E)-CH=CH-4-C6H4NO2 (6); M=Os, R=NO2 (7)], incorporating the optically active diphosphine 1,2-bis(methylphenylphosphino)benzene (diph), are described. Oxidation potentials, as determined by cyclic voltammetry, increase as 2<7<5. Molecular quadratic nonlinearities by hyper-Rayleigh scattering at 1064 nm increase upon introduction of an acceptor group (4<5), chain-lengthening of bridging group (5<6), and proceeding from 3d to 4d and 5d metal (2≤5≤7). Two-level-corrected nonlinearities reproduce the first two trends, but metal variation follows the sequence 2<7<5. The experimental and two-level-corrected nonlinearities for 6 (2795×10−30 and 406×10−30 esu, respectively), are amongst the largest observed thus far for organometallic complexes. Crystals of complexes 2 and 7 exhibit second-harmonic generation (assessed using the Kurtz powder technique), with an efficiency for the former of twice that of urea. 相似文献
18.
Benzyl (2R,3S)-(−)-6-oxo-2,3-diphenyl-4-morpholinecarboxylate (4) was successively alkylated with methyl iodide and 1,4-diiodobutane using a base. In each alkylation step anti-alkylated product formed exclusively. The iodo group was displaced with azide, which served as a precursor for the side-chain amino function. Catalytic hydrogenation with concomitant cleavage of the chiral auxiliary afforded (L)-α-Me-Lys-OH (9) in a total of four steps in good yield. (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained from 9 via regioselective benzyloxycarbonylation. Alternately, (L)-Fmoc-α-Me-Lys(Boc)-OH (16) was obtained via Staudinger reduction of azide (8) in a total of six steps in good yield. 相似文献
19.
Martin Studer Christina Wedemeyer-Exl Felix Spindler Hans-Ulrich Blaser 《Monatshefte für Chemie / Chemical Monthly》2000,131(12):1335-1343
Summary. The first case of an enantioselective hydrogenation of monosubstituted pyridines and furans with homogeneous rhodium diphosphine
catalysts with low but significant enantioselectivities and catalyst activities is reported. Best enantioselectivities (ees of 24–27%) were obtained for the hydrogenation of 2- and 3-pyridine carboxylic acid ethyl ester and 2-furan carboxylic acid
with catalysts prepared in
situ from [Rh(nbd)2]BF4 and the chiral ligands diop, binap, or ferrocenyl diphosphines of the josiphos type. Turnover numbers (ton) were in the order of 10–20, turnover frequencies (tof) usually 1–2 h−1. Diphosphines giving 6- or 7-ring chelates led to higher ees than 1,2-diphosphines; otherwise, no clear correlation between ligand properties and catalytic performance was found. In
some experiments black precipitates were observed at the end of the reaction, indicating the decomposition of the homogeneous
catalysts for certain ligand/metal/substrate combinations.
Received April 5, 2000. Accepted (revised) May 2, 2000 相似文献
20.
Treatment of benzyl α-(1) and methyl β-
-mannopyranoside (2) with α,α-dimethoxytoluene gave the exo and endo isomers (3,5 and 4,6) of the dibenzylidene derivatives of 1 and 2. Hydrogenolysis of the exo isomers (3 and 5) with a molar equivalent of AlH2Cl gave the 3-0-benzyl-4,6-0-benzylidene derivatives (7 and 21), whereas the endo isomers (4 and 6) gave the 2-0-benzyl-4,6-0-benzylidene compounds (8 and 22). The 2-0-allyl ether 9 of 7, the 3-0-allyl derivative (10) of 8 and compounds 21 and 22 were treated with an additional molar equivalent of AlH2Cl at reflux and the products were the 4-0-benzyl-6-hydroxyl derivatives (11, 12, 23 and 24), whereas in the case of 22 the 6-0-benzyl-4-hydroxyl isomer (25) was also isolated. By deallylation of 11 and 12, 3,4-(13) and 2,4-di-0-benzyl (14) ethers of 1 were prepared. Tosylation of 11 and 12, and subsequent reduction of the products (15 and 16) made possible the preparation of the partially protected benzyl α-
-rhamnopyranoside derivatives (17–20). The structures of the compounds synthesized were characterized by 1H and 13C NMR spectroscopic investigation and by chemical methods. 相似文献