Steric effects in the diastereoselective reduction of β-ketosulfones

1988 ◽  
Vol 66 (11) ◽  
pp. 2860-2869 ◽  
Author(s):  
J. Stuart Grossert ◽  
H. Ranjith W. Dharmaratne ◽  
T. Stanley Cameron ◽  
Beverly R. Vincent
Keyword(s):  
Solid State ◽  
Chiral Center ◽  
Nucleophilic Attack ◽  
Resonance Spectroscopy ◽  
Reaction Conditions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Sodium Borohydride Reduction ◽  
Diastereoselective Reduction ◽  
Reduction Of Ketones

The stereochemical course of the reduction of ketones adjacent to a chiral center normally shows some diastereoselectivity (described by Cram's rule), the degree of which is dependent on the structure of the ketone and on the reaction conditions; the selectivity in acyclic species is often not very great. In this paper, we describe the sodium borohydride reduction of four acyclic β-ketosulfones, containing a chiral center at the α position, in which the products are formed with high diastereoselectivity. Reasons for this selectivity became apparent when we were able to show that these ketosulfones apparently exist predominantly in the same conformation in solution as in the solid state. This conformation requires that the preferred trajectory for nucleophilic attack on the carbonyl group leads to reaction on the re face, to yield the threo diastereomer of the β-hydroxysulfone. The results that led to these conclusions were obtained from structural studies by X-ray crystallography, as well as by detailed 1H and 13C nuclear magnetic resonance spectroscopy. In some cases, the latter spectra were run both in solution and in the solid state.

Metal complexes of an amine bisphenol with a thiophene side-arm

2010 ◽  
Vol 75 (10) ◽  
pp. 1051-1060 ◽  
Author(s):  
Eero Salminen ◽  
Reijo Sillanpää ◽  
Ari Lehtonen
Keyword(s):  
Solid State ◽  
Nitrogen Atom ◽  
Dimeric Complex ◽  
State Structure ◽  
Molybdenum Complex ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
X Ray Crystallography ◽  
Phenolic Oxygen

Dioxomolybdenum(VI) and oxotungsten(VI) complexes with a new amine bisphenol ligand (H2L) are reported. The ligand which carries a neutral nitrogen atom, two phenolic oxygen atoms and a thiophene side-arm was synthesized by a simple one-pot Mannich reaction. Further reaction with [MoO2(acac)2] yielded a monomeric molybdenum complex [MoO2(L)(MeOH)] (2a) or a dimeric complex [Mo2O2(μ-O)2(L)2] (2b), depending on the reaction conditions. The reaction with a tungsten trisglycolate [W(eg)3] led to the formation of a monomeric compound [WO(eg)(L)] (3). In these complexes, the potentially tetradentate amine bisphenolate dianion coordinates as a tridentate O,N,O donor while the sulfur side-arm donor remains intact. The solid-state structure of 2a was investigated by X-ray crystallography.

Spectroscopic and crystallographic studies of phosphino adducts of indium(III) iodide

1996 ◽  
Vol 74 (8) ◽  
pp. 1535-1549 ◽  
Author(s):  
Martyn A. Brown ◽  
Dennis G. Tuck ◽  
Edward J. Wells
Keyword(s):  
Crystal Structure ◽  
Coordination Chemistry ◽  
Solid State ◽  
Key Words ◽  
Solution Phase ◽  
Reaction Conditions ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Complete Dissociation

Indium(III) iodide forms both 1:1 and 1:2 adducts with triphenylphosphine, depending on the reaction conditions, and especially on the solvent used. The complex InI3•PPh3 involves four-coordination at indium; the structure is trigonal, with a = 15.105(4) Å, c = 16.769(7) Å, V = 3313(2) Å3, Z = 6, and space group [Formula: see text]. Crystals were also obtained in which InI3•PPh3 and InI3(PPh3)2 are present in a 1:1 ratio; these are also trigonal, a = 15.473(4) Å, c = 41.701(7) Å, V = 8646.1(1.8) Å3,Z = 3 + 3 and space group [Formula: see text]. The 1:2 adduct has approximately D3h symmetry in the InI3P2 kernel. The bond distances and angles are discussed; in particular, the In—P bonds are extremely weak in the 1:2 adduct. This compound has been shown by 31P NMR to undergo complete dissociation in solution to InI3•PPh3 and PPh3. The addition of R4NI (R = n-C3H7, n-C4H9) causes quantitative conversion to InI4− and free Ph3P. Similar experiments are reported for the compound InI3(dppe) (dppe = 1,2-bis(diphenylphosphino)ethane), whose structure is an infinite chain of InI3 units linked through In-P-C2H4-P-In coordination. The crystal structure showed that InI3(dppe) cocrystallizes with an equimolar quantity of dppe; these crystals are cubic, a = 41.445(14) Å, b = 15.944(8) Å, c = 16.533(11) Å, p = 102.02(4)°, V = 10 685(9) Å3, Z = 4 + 4, space group C2/c, Solid state and solution phase results are discussed in terms of the coordination chemistry of indium(III). Key words: indium, phosphorus, coordination chemistry, multinuclear NMR, X-ray crystallography.

scholarly journals A Mixed-metal Mixed-halide Complex Prepared from Zerovalent Copper and Lead Salts: Solution and Solid-state Chemistry

1999 ◽  
Vol 23 (11) ◽  
pp. 670-671
Author(s):  
Larisa A. Kovbasyuk ◽  
Olga Yu. Vassilyeva ◽  
Vladimir N. Kokozay ◽  
Wolfgang Linert ◽  
Paul R. Raithby
Keyword(s):  
Solid State ◽  
Direct Interaction ◽  
Solid State Chemistry ◽  
X Ray ◽  
Mixed Metal ◽  
X Ray Crystallography ◽  
Halide Complex ◽  
Layer Arrangement ◽  
Lead Salts

The mixed-metal mixed-halide complex [CuPbBrlL2]2 has been prepared by the direct interaction of zerovalent copper with lead halides and 2-dimethylaminoethanol (HL) in dmso and has been characterized by X-ray crystallography; the structure shows a layer arrangement of the tetranuclear metal units through the μ3-halogen bridging.

Bis(1-phenyl-1-propyne) complexes of tungsten(II): crystal structures of [WI2(CO)(NCR)(η2-MeC2Ph)2] (R = Me, Et, or Ph)

2001 ◽  
Vol 79 (3) ◽  
pp. 263-271
Author(s):  
Paul K Baker ◽  
Michael GB Drew ◽  
Deborah S Evans
Keyword(s):  
Carbon Monoxide ◽  
Solid State ◽  
Crystal Structures ◽  
Octahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Alkyne Complexes ◽  
First Time

Reaction of [WI2(CO)3(NCMe)2] with two equivalents of 1-phenyl-1-propyne (MeC2Ph) in CH2Cl2, and in the absence of light, gave the bis(1-phenyl-1-propyne) complex [WI2(CO)(NCMe)(η2-MeC2Ph)2] (1) in 77% yield. Treatment of equimolar quantities of 1 and NCR (R = Et, i-Pr, t-Bu, Ph) in CH2Cl2 afforded the nitrile-exchanged products, [WI2(CO)(NCR)(η2-MeC2Ph)2] (2-5) (R = Et (2), i-Pr (3), t-Bu (4), Ph (5)). Complexes 1, 2, and 5 were structurally characterized by X-ray crystallography. All three structures have the same pseudo-octahedral geometry, with the equatorial sites being occupied by cis and parallel alkyne groups, which are trans to the cis-iodo groups. The trans carbon monoxide and acetonitrile ligands occupy the axial sites. In structures 1 and 2, the methyl and phenyl substituents of the 1-phenyl-1-propyne ligands are cis to each other, whereas for the bulkier NCPh complex (5), the methyl and phenyl groups are trans to one another. This is the first time that this arrangement has been observed in the solid state in bis(alkyne) complexes of this type.Key words: bis(1-phenyl-1-propyne), carbonyl, nitrile, diiodo, tungsten(II), crystal structures.

Synthesis and structural characterization of a magnesium phthalocyanine(3–) anion

2012 ◽  
Vol 16 (01) ◽  
pp. 154-162 ◽  
Author(s):  
Edwin W.Y. Wong ◽  
Daniel B. Leznoff
Keyword(s):  
Absorption Spectrum ◽  
Solid State ◽  
Single Crystal ◽  
Structural Characterization ◽  
Heterometallic Complex ◽  
State Structure ◽  
Solid State Structure ◽  
X Ray ◽  
X Ray Crystallography

The reduction of magnesium phthalocyanine (MgPc) with 2.2 equivalents of potassium graphite in 1,2-dimethoxyethane (DME) gives [K2(DME)4]PcMg(OH)(1) in 67% yield. Compound 1 was structurally characterized using single crystal X-ray crystallography and was found to be a monomeric, heterometallic complex consisting of a μ3-OH ligand that bridges a [MgIIPc3-]- anion to two potassium cations solvated by four DME molecules. An absorption spectrum of 1 confirms the Pc ligand is singly reduced and has a 3–charge. The solid-state structure of 1 does not indicate breaking of the aromaticity of the Pc ligand. Compound 1 is only the second Pc3- complex and the first reduced MgPc to be isolated and structurally characterized.

scholarly journals Rational synthesis of an atomically precise carboncone under mild conditions

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw0982 ◽  
Author(s):  
Zheng-Zhong Zhu ◽  
Zuo-Chang Chen ◽  
Yang-Rong Yao ◽  
Cun-Hao Cui ◽  
Shu-Hui Li ◽  
...  
Keyword(s):  
Apex Angle ◽  
Facile Synthesis ◽  
Reaction Conditions ◽  
X Ray ◽  
Carbon Allotropes ◽  
X Ray Crystallography ◽  
Mild Conditions ◽  
Research Opportunity ◽  
Insight Into ◽  
Structural Strain

Carboncones, a special family of all-carbon allotropes, are predicted to have unique properties that distinguish them from fullerenes, carbon nanotubes, and graphenes. Owing to the absence of methods to synthesize atomically well-defined carboncones, however, experimental insight into the nature of pure carboncones has been inaccessible. Herein, we describe a facile synthesis of an atomically well-defined carboncone[1,2] (C70H20) and its soluble penta-mesityl derivative. Identified by x-ray crystallography, the carbon skeleton is a carboncone with the largest possible apex angle. Much of the structural strain is overcome in the final step of converting the bowl-shaped precursor into the rigid carboncone under mild reaction conditions. This work provides a research opportunity for investigations of atomically precise single-layered carboncones having even higher cone walls and/or smaller apex angles.

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

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