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1.
(E)-α-Aryltellurenylvinylsilanes have been synthesized stereoselectively via the hydromagnesiation of alkynylsilanes, followed by the reaction with aryltellurenyl iodides. (E)-α-Aryltellurenylvinylsilanes can undergo the cross coupling reaction with Grignard reagents in the presence of Ni(PPh3)2Cl2 catalyst to afford (Z)-1,2-disubstituted vinylsilanes in good yields.  相似文献   

2.
A (Z)-vinyl (N,N-diisopropyl)carbamate treated with Grignard reagents, under Wenkert Nickel-catalysed conditions, gave access to several substituted (Z)-alkenyl derivatives. These Nickel-catalysed reactions, carried out with vinyl-, phenyl-, p-methoxyphenyl-, trimethylsilylmethylmagnesium bromide and benzylmagnesium chloride, led to the corresponding (Z)-alkenyl derivatives in good yields and high stereoselectivities.  相似文献   

3.
Zhichao Ma 《Tetrahedron》2008,64(27):6500-6509
A Na2S2O4-promoted radical addition reaction of perfluoroalkyl iodides with allenes has been studied in which a Z/E mixture of 2-iodo-1-perfluoroalkyl-2-alkenes 3 were afforded in 52-69% yields. A kinetic resolution using Sonogashira coupling reaction in MeCN using Et2NH as the base was developed to synthesize the 2-iodo-1-perfluoroalkyl-2(Z)-alkenes (Z-3) and E-4-perfluoroalkylmethylalk-4-en-2-ynols (E-5) stereoselectively. A complete Sonogashira coupling procedure in Et2NH at 40 °C was also developed affording a mixture of E and Z-4-perfluoroalkylmethyl-4-en-2-ynols (E-5 and Z-5), which may be easily separated by chromatography on silica gel.  相似文献   

4.
Trifluoromethylated enynyl sulfones 3 were reacted with 2-4 equiv of phenyl, n-hexyl, trimethylsilyl, or triisopropylsilyl substituted ethynyllithium reagents in THF or ether at 0 °C to give trifluoromethylated enediynes 6 (Z)-stereoselectively in 41-96% yields. The reactions of β-fluoro-β-trifluoromethylvinyl sulfone 5 with same ethynyllithium reagents (4 equiv) afforded the corresponding enediynes 6 in 41-90% yields. The cross-coupling reactions of 6 bearing TMS group with aryl iodides in the presence of Pd(PPh3)2Cl2, Ag2CO3, and n-Bu4NBr provided the corresponding enediynes 6 in 20-71% yields. Dimerization of (Z)-6 bearing TMS group in the presence of CuBr2 and K2CO3 yielded dimer (Z,Z)-7 in good yield.  相似文献   

5.
An efficient method for the synthesis of valuable N-, O-, and Si-containing 1Z,5Z-diene compounds was developed. The method comprises Cp2TiCl2-catalyzed homo- and cross-cyclomagnesiation of 1,2-dienes by Grignard reagents (RMgR′) to give 2,5-dialkylidenemagnesacyclopentanes in up to 96% yield. This approach was successfully used in the synthesis of 5Z,9Z-dienoic acids, precursors of acetogenins and insect pheromones.  相似文献   

6.
Four examples of (AxR1−x)R6I12Z phases further illustrate the flexibility of the rhombohedral R7X12Z structure to substitution of heterocations for the isolated RIII atoms without destruction of the structure. The examples with R=La, Pr, Z=Fe, Co, Ir, and stoichiometric amounts of A=Na or Ca were prepared by traditional high temperature techniques and characterized by single crystal and Guinier powder X-ray diffraction techniques. Product compositions refined in the parent space group from reactions of stoichiometry AR6I12Z were (Na0.90Pr0.10)Pr6I12Ir, (Na0.954La0.046)La6I12Fe, and (Ca0.801La0.199)La6I12Co. More general characteristics of and trends in the family of R7X12Z structures are also considered, including distortions of the ideal motif as a function of extremes in the components.  相似文献   

7.
Katsumi Kakinuma 《Tetrahedron》1984,40(11):2089-2094
Chemical synthesis ofD-(6R)- and D(6S)-(6-2H1) glucose is described comprising (i) formation of 6-2H1)-3-o-benzyl-5,6-dideoxy-l, 2-0-isopropylidene-α-D-xylo-hex-5-ynofuranose from D-glucose; (ii) stereospecific reduction of the deuterated acetylene functionality to (E)- or (Z)-deuterated olefin; (iii) stereospecific cis-dihydroxylation of the deuterated olefin; and (iv) separation of stereoisomers based on the intrinsic chirality of D-glucose and subsequent deprotection.  相似文献   

8.
A novel approach to the synthesis of purine nucleoside analogues, featuring the reaction of the C6-N1-O aldonitrone moiety of 9-ribosyl-purine (nebularine) N1-oxide with some representative dipolarophiles, as well as Grignard reagents, is reported. Addition of Grignard reagents to the electrophilic C-6 carbon of the substrate allows a facile access to C-6 C-substituted purine nucleosides without using metal catalysts. 1,3-Dipolar cycloaddition processes lead to novel nucleoside analogues via opening, degradation or ring-enlargement of the pyrimidine ring of the base system of the first-formed isoxazoline or isoxazolidine cycloadduct.  相似文献   

9.
《Polyhedron》1988,7(12):1079-1088
The compounds (ButN)3Re(aryl), (aryl = o-tol, xylyl and mes2), have been prepared from (ButN)3Re(OSiMe3) and the appropriate Grignard reagents. The aryls have been converted to the corresponding dichloride compounds, (ButN)2ReCl2(aryl) by treatment with HCl. The X-ray crystal structure of (ButN)2ReCl2(o-tol) has been determined. The compound has square pyramidal geometry with one linear (basal site) and one bent (axial site) imido group, which formally suggests a 16e configuration.The interaction of xylyl magnesium bromide with [Me3NH] [ReO4] or Re2O7 gives the diamagnetic rhenium(V) complex [(xylyl)2ReO2]2Mg(THF)2, which can be oxidized to the paramagnetic rhenium compound, ReO2(xylyl)2. Interaction of ReO3(OSiMe3) with either xylyl or mesityl Grignard yields ReO2(aryl)2 directly in higher yield. The molecule is tetrahedral.The interaction of OsO4 with xylyl magnesium bromide yields OsO2(xylyl)2. The geometries of the O2MC2 units in MO2(xylyl)2, M = Re and Os, are analogous to those found in the corresponding mesityl derivatives, with the OOsO angle much larger than the OReO angle (139° vs 121°).  相似文献   

10.
《Polyhedron》1987,6(6):1375-1381
N-nitroso-N-alkylhydroxylamines have been prepared by hydrolysis of the mixture obtained by reaction of nitric oxide with Grignard reagents, and stabilized as their copper(II) or iron(III) complexes, Cu(RN2O2)2 and Fe(RN2O2)3, where R is, for example, Me, Et, Pri, Buiso, Ph, n-C8H17 or n-C12H25. The complexes have been characterized by analytical, magnetic and spectroscopic measurements. By single-crystal X-ray methods Cu(PriN2O2)2 has been found to be trans-planar and Fe(PrnN2O2)3 has a facial octahedral structure; in each complex the NO bond lengths are equal with no significant variation between the copper and iron complexes.  相似文献   

11.
Three new quaternary selenites, A2SeMoO6 (A=Na+, K+, or Rb+), were synthesized through the solid-state reaction of A2MoO4 with SeO2 at 400°C. Although the reported materials are ‘stoichiometrically equivalent’, the compounds exhibit strikingly different crystal structures. Whereas Na2SeMoO6 has a three-dimensional crystal structure, K2SeMoO6 and Rb2SeMoO6 are molecular and uni-dimensional, respectively. However, all of the new materials have structures containing Mo6+ octahedra linked to Se4+ trigonal pyramids. Although the Mo6+ and Se4+ cations are in local asymmetric environments in all three materials, only Na2SeMoO6 is non-centrosymmetric. Single crystal X-ray data: Na2SeMoO6, cubic, space group, P213 (no. 198), a=8.375(5) Å, Z=4, R(F)=0.0143; K2SeMoO6, monoclinic, space group, P21/c (no. 14), a=6.118(8) Å, b=15.395(2) Å, c=7.580(9) Å, β=112.39(4)°, Z=4, R(F)=0.0281; Rb2SeMoO6, orthorhombic, space group, Pnma (no. 62), a=7.805(9) Å, b=6.188(7) Å, c=14.405(4) Å, Z=4, R(F)=0.0443.  相似文献   

12.
Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)‐α‐silylvinyl Grignard reagents 2 , which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)‐α‐silylvinyl sulfides 4 in good yields. (E)‐α‐Silylvinyl sulfides 4 could undergo the cross‐coupling reactions with Grignard reagents in the presence of NiCl2(PPh3)2 to give stereoselectively (Z)‐1,2‐disubstituted vinylsilanes 5 . © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:644–647, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20165  相似文献   

13.
The reaction of Lu3+ or Yb3+ and H5IO6 in aqueous media at 180 °C leads to the formation of Yb(IO3)3(H2O) or Lu(IO3)3(H2O), respectively, while the reaction of Yb metal with H5IO6 under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO3)3. Under supercritical conditions Lu3+ reacts with HIO3 and KIO4 to yield the isostructural Lu(IO3)3. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKα, λ=0.71073 Å): Yb(IO3)3, monoclinic, space group P21/n, a=8.6664(9) Å, b=5.9904(6) Å, c=14.8826(15) Å, β=96.931(2)°, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2σ(I); Lu(IO3)3, monoclinic, space group P21/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) Å, β=97.028(2)°, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2σ(I); Yb(IO3)3(H2O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) Å, β=98.636(1)°, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2σ(I); Lu(IO3)3(H2O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) Å, β=98.704(2)°, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2σ(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO3)3(H2O) and Yb(IO3)3(H2O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.  相似文献   

14.
The Pd(PPh3)4-catalyzed isomerization of (Z)-1,4-diacetoxy-2-butene, (Z)-1-(t-butyldimethylsilyloxy)-4-acetoxy-2-butene and (Z)-1-(t-butyldiphenylsilyloxy)-4-acetoxy-2-butene affords the corresponding (E)-isomers and 1,2-difunctionalized-3-butenes. In THF, the formation of the (E)-isomers is mainly due to reaction from an η1-allylpalladium intermediate while an η3-allylpalladium is the main key intermediate in DMF. The time to reach equilibrium between the products and their respective concentrations depend on the nature of the substituents and the solvent.  相似文献   

15.
Single crystals of [H3dien]·(FeF6)·H2O (I) and [H3dien]·(CrF6)·H2O (II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic (Pna21) with a=11.530(2) Å, b=6.6446(8) Å, c=13.787(3) Å, V=1056.3(2) Å3 and Z=4. II is monoclinic (P21/c) with a=13.706(1) Å, b=6.7606(6) Å, c=11.3181(9) Å, β=99.38(1)°, V=1034.7(1) Å3 and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R1/wR2 reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF6 or CrF6 octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by 57Fe Mössbauer spectrometry: the hyperfine structure confirms the presence of Fe3+ in octahedral coordination and reveals the existence of paramagnetic spin fluctuations.  相似文献   

16.
Cationic tetracoordinate nickel(II) compounds containing a nickelcarbon σ bond with general formula [NiR(etp)]Y, (etp  bis(2-diphenylphosphinoethyl)phenylphosphine, PhP(CH2CH2PPh2)2; R = CH3, CH2C6H5, C6H5; Y = BPh4, PF6) were synthesized by reaction of the complexes [NiX(etp)]Y (X = halogen) with appropriate Grignard reagents.This type of organometallic complexes undergo insertion of sulfur dioxide into the NiC bond with formation of tetracoordinate O-sulfinate derivatives of nickel(II). The structure of [NiOS(O)CH3(etp)]BPh4 has been determined from three dimensional X-ray data collected by counter methods. The compound crystallized in the triclinic group P1 with cell dimensions a 16.726(4), a 15.350(4), c 11.632(3) Å, α 66.55(4), β 73.37(4), γ 74.75(4)°, Z = 2. The structure was refined by full matrix least-squares methods to a conventional R factor of 0.076. The coordination polyhedron has a distorted square planar geometry. The sulfinate group is linked to the metal through an oxygen atom.  相似文献   

17.
P. Lhoste  M. Moreau  J. Royer  J. Dreux 《Tetrahedron》1985,41(22):5325-5329
The formation of the dihydropyranol 15 during the synthesis of the 6-hydroxy-4-heptene-2-one (Z) 14 indicates the possibility of an equilibrium between ketols (Z) 5 and pyranols 6. This equilibrium lies well to the side of the pyranol. It might be argued that the dihydropyranol compounds prepared from 2-pyrones and Grignard reagents can be derived from the Z ethylenic ketols.Criteria for the reaction scheme are provided by the stereoselectivity of intermediates in agreement with MNDO (modified neglect of diatomic overlap) calculations.A brief discussion of the present knowledge on the different reaction schemes concerning the reaction of Grignard reagents with 2-pyrones is added.  相似文献   

18.
The new compounds BiMn2PO6, BiMn2AsO6, and BiMn2 VO6 have been prepared and shown to be structurally related to several other BiA2MO6 compounds. The structure of BiMn2PO6 was refined from neutron powder diffraction data in space group Pnma with a=12.04 Å, b=5.37 Å, c=8.13 Å, and Z=4. It contains (BiO2)1− chains and (PO4)3− tetrahedra. The observed fivefold coordination for the Mn2+ cations is unusual for Mn in this oxidation state.  相似文献   

19.
Triplet-state ketones readily sensitized the photoreduction of bis(acetyl-acetonato)cobalt(II) or COsolv2+ under atmospheric pressure of carbon monoxide to give Co(CO)4. The low-valent cobalt could be trapped and isolated as phosphine-substituted metal carbonyl complexes. The crystal structure of one of the products, [Co(CO)(o-C6H4[PPh2]2)2]PF6 has been determined. It is orthorhombic, space group Pbca, Z = 8, with unit cell dimensions a 19.704(5), b 24.850(13), c 21.865(9) Å. Phosphine-substituted iron(0) carbonyl complexes have also been isolated from similar photoreductions of iron(II) species.  相似文献   

20.
A new sodium uranyl vanadate Na(UO2)4(VO4)3 has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. It crystallizes in the tetragonal symmetry with space group I41/amd and following cell parameters: a=7.2267(4) Å and c=34.079(4) Å, V=1779.8(2) Å3, Z=4 with ρmes=5.36(3) g/cm3 and ρcal=5.40(2) g/cm3. A full-matrix least-squares refinement on the basis of F2 yielded R1=0.028 and wR2=0.056 for 52 parameters with 474 independent reflections with I?2σ(I) collected on a BRUKER AXS diffractometer with MoKα radiation and a CCD detector. The crystal structure is characterized by 2[(UO2)2(VO4)] sheets parallel to (001) formed by corner-shared UO6 distorted octahedra and V(2)O4 tetrahedra, connected by V(1)O4 tetrahedra to 1[UO5]4− chains of edge-shared UO7 pentagonal bipyramids alternately parallel to the a- and b-axis. The resulting three-dimensional framework creates mono-dimensional channels running down the a- and b-axis formed by face-shared oxygen octahedra half occupied by Na. The powder of Li analog compound Li(UO2)4(VO4)3 has been synthesized by solid-state reaction. The two compounds exhibit high mobility of the alkaline ions within the two-dimensional network of non-intersecting channels.  相似文献   

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