scholarly journals Synthesis of amphiphilic asymmetrical dithienylethenes with aryl groups at the reactive carbons

2019 ◽  
Vol 97 (6) ◽  
pp. 398-405
Author(s):  
M.S. Jemeli Sang ◽  
Jianxin Cai ◽  
Yamuna S. Kandasamy ◽  
R. Scott Murphy
Keyword(s):  
Steric Hindrance ◽  
Substitution Reaction ◽  
Substituent Effect ◽  
Large Change ◽  
Molecular Geometry ◽  
Methyl Groups ◽  
Synthetic Route ◽  
Aryl Substituent ◽  
Aryl Group ◽  
Enhanced Photostability

A synthetic route for the preparation of amphiphilic asymmetrical dithienylethenes that incorporate methyl groups at the 4- and 4′-positions and an aryl group at one of the reactive carbons has been developed. The presence of a bulky aryl substituent ensures a relatively large change in molecular geometry upon photoisomerization, whereas the presence of methyl groups provide enhanced photostability. Notably, a substituent effect was systematically revealed en route to the preparation of the dithienylethene precursors. In particular, this formal substitution reaction was significantly inhibited due to steric hindrance, stemming from the presence of aryl and methyl groups at the alpha positions of the preformed thienyl carbanionic carbon, and an aryl group on the monosubstituted perfluorocyclopentene derivative.

The Rates and Products of Addition of 4-Chlorobenzenesulfenyl Chloride to a Series of Side Chain Methyl Substituted Styrenes

1974 ◽  
Vol 52 (9) ◽  
pp. 1807-1812 ◽  
Author(s):  
George H. Schmid ◽  
Dennis G. Garratt
Keyword(s):  
Steric Hindrance ◽  
Side Chain ◽  
Methyl Groups ◽  
Methyl Group

The rates of addition and the product compositions have been determined for the addition of 4-chlorobenzenesulfenyl chloride to a series of seven side chain methyl substituted styrenes in 1,1,2,2-tetrachloroethane at 25°. Unlike the addition to the corresponding series of methylated ethylenes, the effect of the methyl groups is not cumulative. The effect of the methyl groups depends upon whether or not the β-methyl group is cis to the phenyl. When it is cis, the rate of addition is decreased compared to styrene and substitution of additional methyl groups has only a small effect on the rate of addition. In compounds lacking a cis-β-methyl group the rate of addition more closely resembles that for addition to the methylated ethylenes. Steric hindrance between the cis-methyl and phenyl groups is believed to be the cause of this difference in behavior between the ethylene and styrene series.

The Molecular Geometry of Diastereoisomeric Bis[α-(9-anthryl)ethyl] Ethers

1985 ◽  
Vol 38 (9) ◽  
pp. 1417 ◽  
Author(s):  
H Becker ◽  
VA Patrick ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Least Squares ◽  
Dihedral Angle ◽  
Molecular Geometry ◽  
Dihedral Angles ◽  
Methyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Meso Form ◽  
Aromatic Systems

The crystal structures of racemic bis [α-(9-anthryl)] ether and its meso form have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by least squares to residuals of 0.053 and 0.041 for 1868 and 3568 independent 'observed' reflections respectively. Crystals of the racemate are orthorhombic, Pcab, a 23.07(1), b 19.85(2), c 10.241(8) Ǻ, Z 8. Crystals of the meso form are triclinic, Pī , a 19.032(12), b 14.207(11), c 9.451(8) Ǻ, α 79.46(6), β 89.68(6), γ 68.97(5)°, Z 4. In the racemate , the dihedral angle between the methyl groups along the ether bonds is 12°, and the short axes of the anthracene moieties lie at an angle of about 120°. In the meso compound, for the two molecules the dihedral angles between the methyl groups along the ether bonds are 90 and 93°, the angle between the two anthracene moieties is 90°, and the interplanar angles between the partly overlapping aromatic systems are 46 and 43°.

Chlorido(dimethyl 2,2′-bipyridine-4,4′-dicarboxylate-κ2N,N′)(η5-pentamethylcyclopentadienyl)rhodium(III) chloride 1-hydroxypyrrolidine-2,5-dione disolvate

2013 ◽  
Vol 69 (6) ◽  
pp. 584-587
Author(s):  
Dharmalingam Sivanesan ◽  
Hyung Min Kim ◽  
Yoon Sungho
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Substitution Reaction ◽  
Three Dimensional ◽  
Title Complex ◽  
Rhodium Complex ◽  
Synthetic Route ◽  
Dimensional Network ◽  
Weak Hydrogen Bonds ◽  
Solvent Molecules

The title complex, [Rh(C10H15)Cl(C14H12N2O4)]Cl·2C4H5NO3, has been synthesized by a substitution reaction of the precursor [bis(2,5-dioxopyrrolidin-1-yl) 2,2′-bipyridine-4,4′-dicarboxylate]chlorido(pentamethylcyclopentadienyl)rhodium(III) chloride with NaOCH3. The RhIIIcation is located in an RhC5N2Cl eight-coordinated environment. In the crystal, 1-hydroxypyrrolidine-2,5-dione (NHS) solvent molecules form strong hydrogen bonds with the Cl−counter-anions in the lattice and weak hydrogen bonds with the pentamethylcyclopentadienyl (Cp*) ligands. Hydrogen bonding between the Cp* ligands, the NHS solvent molecules and the Cl−counter-anions form links in a V-shaped chain of RhIIIcomplex cations along thecaxis. Weak hydrogen bonds between the dimethyl 2,2′-bipyridine-4,4′-dicarboxylate ligands and the Cl−counter-anions connect the components into a supramolecular three-dimensional network. The synthetic route to the dimethyl 2,2′-bipyridine-4,4′-dicarboxylate-containing rhodium complex from the [bis(2,5-dioxopyrrolidin-1-yl) 2,2′-bipyridine-4,4′-dicarboxylate]rhodium(III) precursor may be applied to link Rh catalysts to the surface of electrodes.

scholarly journals Chemically Fueled Transient Geometry Changes in Diphenic Acids

2020 ◽  
Author(s):  
Isuru Jayalath ◽  
Hehe Wang ◽  
Georgia Mantel ◽  
Lasith S. Kariyawasam ◽  
Scott Hartley
Keyword(s):  
Quantitative Analysis ◽  
Kinetic Parameters ◽  
Dihedral Angle ◽  
Steric Hindrance ◽  
Molecular Geometry ◽  
Torsional Angle ◽  
Fuel Treatment ◽  
Simple Mechanism ◽  
Ethylcarbodiimide Hydrochloride ◽  
Biochemical Systems

Transient changes in molecular geometry are key to the function of many important biochemical systems. Here, we show that diphenic acids undergo out-of-equilibrium changes in dihedral angle when reacted with a carbodiimide chemical fuel. Treatment of appropriately functionalized diphenic acids with EDC (<i>N</i>-(3-dimethylaminopropyl)-<i>N</i>′-ethylcarbodiimide hydrochloride) yields the corresponding diphenic anhydrides, reducing the torsional angle about the biaryl bond by approximately 45°, regardless of substitution. In the absence of steric resistance, the reaction is well-described by a simple mechanism; the resulting kinetic parameters can be used to derive important properties of the system, such as yields and lifetimes. The reaction tolerates steric hindrance ortho to the biaryl bond, although the competing formation of (transient) byproducts complicates quantitative analysis.

Velocity of rearrangement of ortho-substituted 3-(X-benzal)phthalides into 2-(X-phenyl)-1,3-indanediones and study of ortho-effect

1980 ◽  
Vol 45 (4) ◽  
pp. 1072-1078 ◽  
Author(s):  
Ľudovít Krasnec ◽  
Pavol Hrnčiar ◽  
Anton Gáplovský
Keyword(s):  
Rate Constant ◽  
Steric Hindrance ◽  
Substituent Effect ◽  
Sodium Methoxide ◽  
Second Order ◽  
Reaction Centre ◽  
Ortho Effect ◽  
Concentration Dependences

Velocity of the second order rearrangement of ortho-substituted 3-(X-benzal)phthalides into respective 2-(X-phenyl)-1,3-indanediones by action of methanolic sodium methoxide has been studied spectrophotometrically. The values of logarithm of the rate constant obtained by extrapolation of the concentration dependences to zero concentration of methoxide have been correlated with σ, σ0, σ+, F, R, and Es constants of the substituents and with the Charton ν constant for the ortho-substituted derivatives. The obtained dependences log k vs the mentioned constants have been compared with the corresponding dependences of the rearrangement of the meta- and para-substituted 3-(X-benzal)phthalides into the respective 3-(X-phenyl)-1,3-indanediones. Transmission of the substituent effect on the reaction centre is almost the same from ortho and from para position. Possible ortho-effect and steric hindrance of the substituents have been followed.

Stereoselective Aminoiodination of Activated Alkynes with Organoiodine(III) Reagents and Amines via Multiple-Site Functionalization: Access to Iodinated Enamines and N-Aryl Indoles

2019 ◽  
Author(s):  
sagar arepally ◽  
Narenderreddy Katta ◽  
Ajoy Chamuah ◽  
Sharada Duddu. S
Keyword(s):  
Hydrogen Bonding ◽  
Steric Hindrance ◽  
Single Step ◽  
Multiple Site ◽  
Aryl Group ◽  
Mild Conditions ◽  
Reaction Proceeds ◽  
Activated Alkynes ◽  
Acidic Conditions ◽  
High Stereoselectivity

<p>A stereoselective aminoiodination of activated alkynes with PhI(OAc)<sub>2</sub> and amines <i>via</i> multiple-site functionalization to afford (<i>Z</i>)diethyl 2-(diphenylamino)-3-iodomaleate derivatives with superior yields has been described. The key feature of this reaction is the incorporation of iodide and aryl group concurrently in the same molecule in a stereoselective manner by employing PhI(OAc)<sub>2</sub> as electrophilic reagent as well as iodide and aryl group source. The high stereoselectivity of the reaction can be explained based on the structure of the possible intermediates, the conformations of which controlled by the hydrogen bonding, steric hindrance and electrostatic attractions. This reaction proceeds under mild conditions, providing various dialkyl 2-(diphenylamino)-3-iodomaleates by a single operation starting from activated alkynes. The robustness of our strategy is revealed by making of bis (dialkyl 2-(diphenylamino)-3-iodomaleate) derivatives involving formation of four new C-N bonds and two C-I bonds with a single step. The synthesized inactive 3° enamines (dialkyl 2-(diphenylamino)-3-iodomaleates) could be further transformed into highly substituted indoles via Pd catalyzed C-H and C-I activation under non-acidic conditions. </p><br>

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