Diels–Alder adducts of 2-acetoxyfuran as a route to 2,3-functionalized 4-hydroxycyclohexanones. Application of X-ray diffraction to the problem of regio- and stereochemistry

1981 ◽  
Vol 59 (20) ◽  
pp. 2997-3006 ◽  
Author(s):  
D. Gravel ◽  
R. Deziel ◽  
F. Brisse ◽  
L. Hechler
Keyword(s):  
Maleic Anhydride ◽  
Sodium Methoxide ◽  
Diels Alder ◽  
Quantitative Yield ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Efficient Access ◽  
Reaction Proceeds ◽  
Cyclopropane Derivatives

The Diels–Alder adducts of 2-acetoxyfuran and maleic anhydride and 2-acetoxyfuran and chloromethylmaleic anhydride have been obtained and their dihydro derivatives manipulated in high yield to various 2,3-functionalized 4-hydroxycyclohexanones. In all cases the hemiketal acetate bridge of the oxabicyclo[2.2.1] derivatives was cleaved smoothly using sodium methoxide in methanol at 0 °C; however, in the case of the chloromethyl compounds the reaction proceeds further to give an almost quantitative yield of the corresponding fused cyclopropane derivatives. These sequences, starting from the readily accessible but seldom used 2-acetoxyfuran, are therefore extremely advantageous to gain rapid and efficient access to a number of 2,3-functionalized 4-hydroxycyclohexanones. In the case of the adduct involving chloromethylmaleic anhydride, stereochemistry and regiochemistry were established by X-ray diffraction on the dihydro derivative.

High-yield, regiospecific bis-functionalization of C70 using a Diels–Alder reaction in molten anthracene

2014 ◽  
Vol 50 (73) ◽  
pp. 10584-10587 ◽  
Author(s):  
Venkata S. Pavan K. Neti ◽  
Maira R. Cerón ◽  
A. Duarte-Ruiz ◽  
Marilyn M. Olmstead ◽  
Alan L. Balch ◽  
...  
Keyword(s):  
Single Crystal ◽  
Thermal Gravimetric Analysis ◽  
Alder Reaction ◽  
Diels Alder ◽  
High Yield ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diels Alder Reaction

A regiospecific bis-adduct of C70 with anthracene was prepared with unusually high yield (68%) by the Diels–Alder reaction in the absence of solvent (melt). The structure of the bis-adduct was an unexpected 12 o'clock isomer, as determined by single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and spectroscopy.

Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]

1993 ◽  
Vol 58 (12) ◽  
pp. 2924-2935 ◽  
Author(s):  
Jane H. Jones ◽  
Bohumil Štíbr ◽  
John D. Kennedy ◽  
Mark Thornton-Pett
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
High Yield ◽  
Monoclinic Space Group ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
X Ray ◽  
Yield Formation ◽  
Boiling Toluene

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

Phosphonium salts. III. The action of cyanide ion and other nucleophiles on some bis-phosphonium salts

1969 ◽  
Vol 22 (7) ◽  
pp. 1405 ◽  
Author(s):  
JJ Brophy ◽  
MJ Gallagher
Keyword(s):  
Sodium Azide ◽  
Sodium Methoxide ◽  
Sodium Acetate ◽  
Potassium Cyanide ◽  
Dimethyl Sulphoxide ◽  
High Yield ◽  
Phosphonium Salts ◽  
Elimination Reaction ◽  
Cyanide Ion ◽  
Reaction Proceeds

Cyclic and acyclic bis-phosphonium salts with a two-carbon bridge are smoothly cleaved to phosphines in high yield by potassium cyanide in dimethyl sulphoxide. Evidence is presented that the reaction proceeds by an elimination-addition sequence. An elimination reaction also occurs when sodium methoxide, sodium azide, sodium acetate, and triethylamine react with ethane-1,2-bis(tri-phenylphosphonium) dibromide. ��� In a novel reaction, triphenylphosphine is converted into its oxide by a mixture of sodium azide and dimethyl sulphoxide.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

A Simple High-Yield Synthesis of Gallium(I) Tetrachlorogallate(III) and the Reaction of Digallium Tetrachloride Tetrahydrofuran Solvate with 1,2-Diols

2001 ◽  
Vol 56 (4-5) ◽  
pp. 337-341 ◽  
Author(s):  
Eva S. Schmidt ◽  
Annette Schier ◽  
Norbert W. Mitzel ◽  
Hubert Schmidbaur
Keyword(s):  
Crystalline Phase ◽  
Hydrogen Gas ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Atoms ◽  
Gallium Hydride ◽  
Hydroxy Groups ◽  
Tetrahydrofuran Solution ◽  
Analogous Product

Abstract Gallium(I) tetrachlorogallate(III) Ga[GaCU] was prepared in quantitative yield by thermal de­composition of dichlorogallane [HGaCl2]2, which is readily available from Et3SiH and [GaCl3]2. The reaction of catechol with solutions of this gallium(I) tetrachlorogallate(III) in tetrahydrofuran leads to the evolution of hydrogen gas and affords a dinuclear gallium(III) complex with penta-coordinate metal atoms chelated and bridged by mono-deprotonated catechol ligands. In the crystalline phase tetrahydrofuran molecules are hydrogen-bonded to the hydroxy groups: [Ga(1,2 -OC6H4OH)Cl2(C4H8O)]2. The reaction with pinacol also gives hydrogen and the analogous product [Ga(OCMe2CMe2OH)Cl2(C4H8O)]2. The structures of the two compounds have been determined by X-ray diffraction. A mechanism of the new reaction has been proposed which involves oxidative addition of the diol to the solvate (THF)Cl2Ga-GaCl2(THF) present in the tetrahydrofuran solution to give a gallium hydride intermediate.

A Conformational Analysis of the Spirocyclic Quaternary Ammonium Cation [(CH2)4N(CH2)4]+ in its Bromide and Picrate Salts

2004 ◽  
Vol 59 (3) ◽  
pp. 259-263 ◽  
Author(s):  
Uwe Monkowius ◽  
Stefan Nogai ◽  
Hubert Schmidbaur
Keyword(s):  
Gas Phase ◽  
Quaternary Ammonium ◽  
Point Group ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quaternary Ammonium Cations ◽  
Twist Conformation ◽  
Twist Form ◽  
Group D

High-yield syntheses of the bromide (1a) and picrate salts (1b) of the 5-azonia-spiro[4]nonane cation [(CH2)4N(CH2)4]+ are reported. In the single crystal X-ray diffraction analyses of the two salts the spirocyclic quaternary ammonium cations have their five-membered rings in envelop and twist conformations modified by packing forces. The conformation found experimentally for 1a has C2-symmetry as predicted for the gas phase by quantum-chemical calculations (RI-DFT, RI-MP2), but the five-membered rings are intermediate between the expected envelop and the twist form. For 1b, both of the two independent cations can be described as a combination of rings in an envelop and a twist conformation. According to the NMR spectra, in solution the cations are highly flexible and pseudosymmetrical (point group D2d)

Green rust as a precursor for magnetite: an in situ synchrotron based study

2008 ◽  
Vol 72 (1) ◽  
pp. 201-204 ◽  
Author(s):  
A. Sumoondur ◽  
S. Shaw ◽  
I. Ahmed ◽  
L. G. Benning
Keyword(s):  
Direct Evidence ◽  
Green Rust ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Subsequent Transformation ◽  
Rapid Formation ◽  
Reaction Proceeds

AbstractIn this study, direct evidence for the formation of magnetite via a green rust intermediate is reported. The Fe(II) induced transformation of ferrihydrite, was quantified in situ and under O2-free conditions using synchrotron-based time-resolved energy dispersive X-ray diffraction. At pH 9 and Fe(II)/Fe(III) ratios of 0.5 and 1, rapid growth (6 min) of sulphate green rust and its subsequent transformation to magnetite was observed. Electron microscopy confirmed these results, showing the initial rapid formation of hexagonal sulphate green rust particles, followed by the corrosion of the green rust as magnetite growth occurred, indicating that the reaction proceeds via a dissolution-reprecipitation mechanism. At pH 7 and Fe(II)/Fe(III) ratio of 0.5, sulphate green rust was the stable phase, with no transformation to magnetite.

scholarly journals Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Daisuke Ogawa ◽  
Ryo Kitaura ◽  
Takeshi Saito ◽  
Shinobu Aoyagi ◽  
Eiji Nishibori ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Yield ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Single Wall Carbon ◽  
X Ray ◽  
Transmission Electron ◽  
Organometallic Molecules ◽  
X Ray Absorption

Thermally fragile tris(η5-cyclopentadienyl)erbium (ErCp3) molecules are encapsulated in single-wall carbon nanotubes (SWCNTs) with high yield. We realized the encapsulation of ErCp3with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+) is confirmed by X-ray absorption spectrum.

Pentamethylcyclopentadienyl-Vanadium Complexes Containing Halogeno- and Oxo-Ligands

1987 ◽  
Vol 42 (12) ◽  
pp. 1520-1526 ◽  
Author(s):  
Max Herberhold ◽  
Walter Kremnitz ◽  
Markus Kuhnlein ◽  
Manfred L. Ziegler ◽  
Karl Brunn
Keyword(s):  
Crystal Structure ◽  
Mass Spectra ◽  
High Yield ◽  
Vanadium Complexes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths ◽  
Oxygen Bond ◽  
Single Bonds ◽  
Oxo Ligands

AbstractA simple and high-yield preparation of the pentamethylcyclopentadienyl vanadium(IV) trihalides Cp*VX3 (X = CL, Br, I) from Cp*V(CO)4 as well as their conversion into the oxo-vanadium(V) compounds Cp*VOX2 (X = CL, Br) and [Cp*VOX]2(μ-O) (X = CL, Br, I) are described. The equilibrium between the two fluoride species Cp*VOF2 and [Cp*VOF]2(μ-O) has also been investigated. The complexes are characterized by their NMR (51V, l3C, 1H), IR, and mass spectra. The crystal structure of the binuclear chloro-oxo complex [Cp*VOCl]2(μ-O) has been determined by X-ray diffraction. The molecules contain two [Cp*VOCl] units combined via a bent oxo bridge (V-O-V angle of 142.2(2)°). The vanadium-oxygen bond lengths are 157.6(8) and 179.4(1) pm for the terminal and the bridging oxo ligands, respectively, corresponding to double and single bonds.

1,2-Di(silyl)benzene and 1,4-Dibromo-2,5-di(silyl)benzene

1994 ◽  
Vol 49 (8) ◽  
pp. 1036-1040 ◽  
Author(s):  
Robert Schröck ◽  
Alexander Sladek ◽  
Hubert Schmidbaur
Keyword(s):  
Methanesulfonic Acid ◽  
Intermediate Compound ◽  
Molecular Structures ◽  
High Yield ◽  
Electronic Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Yields ◽  
Experimental Findings ◽  
Silylation Reaction

1,2-Di(silyl)benzene (3), has been prepared in a three-step process starting with the reac­tion of 1,2-dibromobenzene and p-tolyl(chloro)silane with magnesium in tetrahydrofuran. which affords 1,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1,2-bis(trifluoromethanesulfonatosilyl)benzene (2) with trifluoro- methanesulfonic acid, and finally into 3 by reduction with lithiumaluminiumhydride, both again in high yields. - In an attempt to prepare 1,2,4,5-tetra(silyl)benzene in an analogous way. only the bis-silylated species could be obtained (from 1,2,4,5-C6H2Br4. p-MeC6H4SiClH2 and Mg powder: 1,4-dibromo-2,5-bis(p-tolylsilyl)benzene. 4, and 1,4-dibromo-2,5-di(silyl)- benzene, 6, via 1,4-dibromo-2,5-bis(trifluoromethanesulfonatosilyl)benzene, 5). The crystal structures of compounds 4 and 6 have been determined by X-ray diffraction. The results indicate no steric hindrance in these molecules and it is thus not obvious from the molecular structures why the silylation reaction does not proceed any further to give the tetrasilylated benzene derivatives. Electronic effects have to be invoked to rationalize the experimental findings.

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