- Crystal structures and energy refinement of some 2,2'-disubstituted biphenyl compounds
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Synthesis and structural determination by X-ray crystallography of three substituted biphenyl structures are reported: (2) is monoclinic P21/n with a = 10.805(4), b = 8.079(3), c = 16.232(6) Angstroem, β = 100.96(5) deg; (4) is monoclinic P21/n with a = 9.966(3), b = 10.007(3), c = 13.053(4) Angstroem, β = 96.74(5) deg; (5) is triclinic P with a = 12.033(5), b = 16.903(8), c = 9.752(4) Angstroem, α = 94.70(3) deg, β = 112.56(3) deg, γ = 76.12(3) deg.In all compounds the biphenyl has two identical substituents in an ortho position to the center inter-ring bond and present variable inter-ring twist angles.In the process of investigating molecular geometry, we are interested in studying whether the calculated conformations of our molecules can fit the crystallographic structures.
- Benmenni, L.,Alilou, E. H.,Giorgi, M.,Pierrot, M.,Reglier, M.
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- 2,2′-Bis(methylene)biphenylidene-bridged bis(3-indenyl) dichloride complexes of Ti, Zr and Hf as catalyst precursors for ethylene polymerization
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ansa metallocene complexes of Ti, Zr and Hf were synthesized, characterized and tested as catalysts for homogeneous ethylene polymerization. The ligand system comprises two indenyl moieties tethered at the 1,1′-positions via a 2,2′-dimethyl biphenylene bridge. The ligand precursor was obtained by the reduction of diphenic acid using lithium aluminum hydride (LiAlH4), followed by the reaction with phosphorus tribromide, and, finally, the reaction with indenyllithium. The corresponding group (IV) metal complexes were synthesized by deprotonation of the ligand precursors using n-BuLi followed by reactions of the corresponding metal tetrachloride. After activation with methylaluminoxane (MAO), the zirconium and hafnium complexes proved as highly active catalysts for ethylene polymerization. The zirconium complex 6 showed the best performance with 12,460 kg PE/mol cat. h. The titanium complex 5 showed no catalytic activity obviously because of decomposition reactions.
- Abdelbagi, Mohamed E.M.,Mondal, Swastik,van Smaalen, Sander,Alt, Helmut G.
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- Cu-catalyzed enantioselective alkylarylation of vinylarenes enabled by chiral binaphthyl-box hybrid ligands
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Transition-metal-catalyzed radical relay coupling reactions have recently emerged as one of the most powerful methods to achieve difunctionalization of olefins. However, there has been limited success in applying this method to asymmetric catalysis using an effective chiral ligand. Herein we report the Cu-catalyzed enantioselective alkylarylation of vinylarenes using alkylsilyl peroxides as alkyl radical sources. This reaction proceeds under practical reaction conditions and affords chiral 1,1-diarylalkane structures that are found in a variety of bioactive molecules. Notably, a highly enantioselective reaction was accomplished by combining chiral bis(oxazoline) ligands with chiral binaphthyl scaffolds.
- Sakurai, Shunya,Matsumoto, Akira,Kano, Taichi,Maruoka, Keiji
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supporting information
p. 19017 - 19022
(2020/11/02)
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- Gold(I) Complexes Stabilized by Nine- and Ten-Membered N-Heterocyclic Carbene Ligands
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Nine- and ten-membered N-heterocyclic carbene (NHC) ligands have been developed and for the first time their gold(I) complexes were synthesized. The protonated NHC pro-ligands 2 a–h were prepared by the reaction of readily available N,N′-diarylformamidines with bis-electrophilic building blocks, followed by anion exchange. In situ deprotonation of the tetrafluoroborates 2 a–h with tBuOK in the presence of AuCl(SMe2) provided fast access to NHC-gold(I) complexes 3–10. These new NHC-gold(I) complexes show very good catalytic activity in a cycloisomerization reaction (0.1 mol % catalyst loading, up to 100 % conversion) and their solid-state structures reveal high steric hindrance around the metal atom (%Vbur up to 53.0) which is caused by their expanded-ring architecture.
- Cervantes-Reyes, Alejandro,Rominger, Frank,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 11745 - 11757
(2019/08/20)
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- 1-Aminobenzocyclobutene-1-phosphonic Acid and Related Compounds as Inhibitors of Phenylalanine Ammonia-Lyase
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Five new geminal aminocycloalkanephosphonic acids (4 – 8) containing both an aromatic ring and a cycloalkane ring were synthesized and evaluated as potential inhibitors of buckwheat phenylalanine ammonia-lyase (PAL). Within the set of compounds which are related to 2-aminoindane-2-phosphonic acid (AIP, 3), a known powerful inhibitor of PAL, racemic 1-aminobenzocyclobutene-1-phosphonic acid (4), was six times weaker than AIP as an in vitro inhibitor of buckwheat PAL, but six times stronger than AIP as an in vivo inhibitor of phenylalanine-derived anthocyanin synthesis in buckwheat.
- Zoń, Jerzy,Miziak, Piotr
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- A Binaphthyl-Based Scaffold for a Chiral Dirhodium(II) Biscarboxylate Ligand with α-Quaternary Carbon Centers
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A chiral dirhodium(II) paddlewheel complex has been synthesized from biscarboxylate ligands derived from BINOL, and the resulting complex has been used in enantioselective carbene/alkyne cascade reactions. The ligand design was guided by requirements of α
- Chen, Po-An,Setthakarn, Krit,May, Jeremy A.
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p. 6155 - 6161
(2017/09/15)
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- Synthesis of biphenyl-based ligand: Application in copper-mediated chemoselective michael reaction
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A biphenyl-based ligand attached was synthesized and screened in copper-mediated Michael reaction. The catalyst system works well with carbon or sulfur nucleophiles as Michael donors and cyclohexenone or chalcones as the acceptors under mild and neutral r
- Sundar, M. Shyam,Bedekar, Ashutosh V.
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supporting information
p. 3582 - 3593
(2015/08/11)
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- Design, synthesis and in vitro evaluation of novel bivalent S-adenosylmethionine analogues
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In optimal cases, bivalent ligands can bind with exceptionally high affinity to their protein targets. However, designing optimised linkers, that orient the two binding groups perfectly, is challenging, and yet crucial in both fragment-based ligand design
- Joce, Catherine,White, Rebecca,Stockley, Peter G.,Warriner, Stuart,Turnbull, W. Bruce,Nelson, Adam
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supporting information; experimental part
p. 278 - 284
(2012/03/11)
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- Highly enantioselective aldol reactions using a tropos dibenz[c,e]azepine organocatalyst
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The four-step synthesis of a chiral primary tertiary diamine salt, possessing a tropos dibenz[c,e]azepine ring is described. It is shown that 3.5-5 mol % of this salt is capable of promoting highly enantioselective crossed-aldol reactions between cyclohexanone and a series of aromatic aldehydes. In all cases, the aldol reactions proceed with high diastereoselectivity for the anti-aldol product. The outcome of crossed-aldol reactions involving other cyclic ketones and acyclic ketones are also described. All examples involving cyclic ketones result in selectivity for the anti-aldol products, whereas acyclic ketones were found to favour the syn-aldol products. A discussion on the role of the chiral primary tertiary diamine salt in the catalysis of the aldol reactions is also presented.
- Lygo, Barry,Davison, Christopher,Evans, Timothy,Gilks, James A.R.,Leonard, John,Roy, Claude-Eric
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experimental part
p. 10164 - 10170
(2012/01/03)
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- Flow-vacuum pyrolysis of dibenzocycloheptane annelated derivative on zeolites catalysts
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The pyrolysis of 5H-6,7-dihydrodibenzo[a,c]cyclohepten-6-ol (5) in FVP conditions, a method of thermal decomposition in advanced vacuum, inert atmosphere on zeolites/acid Al2O3 at variable temperature between 300- 350° C is presented. The reaction products were identified by GC/MS using authentic samples and a reaction mechanism involving cationic species as intermediates was proposed. A comparison with the pyrolysis of the same compound performed in FVP conditions on quartz is presented.
- Istrati, Daniela,Parvulescu, Luminitza,Popescu, Angela,Mihaiescu, Dan,Andrei, Elena,Badea, Florin
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p. 847 - 850
(2011/06/21)
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- Asymmetric phase-transfer catalysis of homo- and heterochiral quaternary ammonium salts: development and application of conformationally flexible chiral phase-transfer catalysts
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Inspired by the considerable difference of catalytic activity and stereocontrolling ability between the conformationally rigid, homo- and heterochiral quaternary ammonium bromides 1, conformationally flexible, N-spiro chiral quaternary ammonium bromides o
- Ooi, Takashi,Uematsu, Yukitaka,Kameda, Minoru,Maruoka, Keiji
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p. 11425 - 11436
(2007/10/03)
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- Asymmetric activation of tropos catalysts in the stereoselective catalytic conjugate additions of R2Zn to α,β-enones: An efficient synthesis of (-)-muscone
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The preparation of a new phosphoramidite starting from (R)-BINOL and a biphenylamine is presented. In such a compound the chirality is due only to atropisomerism and this molecule possesses a flexible biphenylamine residue. Therefore it can work as a tropos catalyst. The catalytic efficiency of this new phosphoramidite has been tested in some asymmetric conjugate additions of dialkylzinc reagents to α,β-enones and compared with that of an analogous already known non-tropos ligand. Interestingly, while comparable results were obtained in the addition of ZnEt2 to chalcone and cyclohexenone, in the case of the addition of ZnMe2 to (E)-cyclopentadec-2-en-1-one, the new ligand provides (-)-muscone, a valuable ingredient of the perfume industry, in 84% ee, while the non-tropos ligand gives a much lower (57%) ee value. Graphical Abstract
- Scafato, Patrizia,Cunsolo, Giovanni,Labano, Stefania,Rosini, Carlo
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p. 8801 - 8806
(2007/10/03)
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- Dicyanomethylene compounds as cyanation reagents
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Ethenetetracarbonitrile (2, in benzene solution) and 1,3-dioxoindan-2-ylidene propanedinitrile (4, in ethanol or acetonitrile solution) act on N-aryl-2,3-dihydro-1H-benz[d,e]isoquinolines 6a-d and N-aryl-6,7-dihydro-5H-dibenz[c,e]azepines 11a-d via hydrid
- D?pp, Dietrich,Jüschke, Sabine,Henkel, Gerald
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p. 460 - 470
(2007/10/03)
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- Reductive cleavage of benzannelated cyclic ethers and amines: Synthetic applications
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Reduction of symmetrical intramolecular diarylmethyl ethers (3a and 8a) and amines (3b and 8b) with alkali metals in THF allows the generation of unsymmetrical oxy- or amino-functionalised arylmethyl organometallics. Such intermediates were successfully trapped with various electrophiles, allowing a new access to unsymmetrically 2,2'-disubstituted-1,1'-biaryls (5aa-5bf) and 1,8-disubstituted naphthalenes (10aa-10be). (C) 2000 Elsevier Science Ltd.
- Azzena, Ugo,Demartis, Salvatore,Pilo, Luciano,Piras, Elisabetta
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p. 8375 - 8382
(2007/10/03)
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- Preparation of bidentate ligands
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The process for preparing a bidentate ligand comprising the steps, (1) contacting with ozone under ozonolysis conditions a suspension in a hydroxylic reaction medium of phenanthrene or a phenanthrene derivative to form an ozonated intermediate, (2) contacting said ozonated intermediate with a reducing agent under conditions appropriate to form the corresponding diol, (3) contacting said diol with a latent displaceable functional group under conditions appropriate to convert the diol to the corresponding difunctional biaryl compound, and (4) contacting said difunctional biaryl compound, with an anion of N, P, As, Sb or Bi under conditions appropriate to form the desired bidentate ligand.
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- Synthesis and Multinuclear NMR Characterizations of Some Diselena- and Tetraselenacyclophanes.
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Several symmetrical and unsymmetrical bis-selenacyclophanes were prepared and characterized by multinuclear (1H, 13C and 77Se) NMR.The symmetrical cyclophanes of phenyl, furyl, pyridyl and thiophenyl appear to exist in predominantly syn conformation in solution at room temperature.VT-1H NMR of some cyclophanes indicate that the equilibrium between the syn conformers which differ in the disposition of the bridge seleniums (symmetric about mirror plane symmetric about inversion center) can be slowed at low temperatures.Interesting 13C shifts are observed in unsymmetrical cyclophanes containing 2,2'-biphenyl, pyridine and furan.The 77Se chemical shifts appear to be related to the size of the cavity of the cyclophanes.
- Hojjatie, Massoud,Muralidharan, Subramaniam,Freiser, Henry
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p. 1611 - 1622
(2007/10/02)
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- Low pressure hydroformylation of dienes
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A hydroformylation process for preparing dialdehydes from dienes by contacting a C6 -C10 diene in a reaction zone at a temperature of from about 20° C. to about 250° C. and a pressure of from about 15 psig to about 800 psig with hydrogen, carbon monoxide, and a catalyst containing rhodium, the ligand having the formula STR1 wherein: n is 1-4; each R is independently selected from hydrogen, alkyl, alkoxy, aryloxy, aryl, aralkyl, alkaryl, alkoxyalkyl, cycloaliphatic, halogen, alkanoyl, alkanoyloxy, alkoxycarbonyl, carboxyl or cyano; each R1 and R2 is independently selected from alkyl, aryl, aralkyl, alkaryl or cycloaliphatic; each R3 and R4 is independently selected from hydrogen and the R1 substituents; and each Y is independently selected from the elements N, P, As, Sb and Bi.
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- Chelate ligands for low pressure hydroformylation catalyst and process employing same
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A novel ligand for use in hydroformylation reactions wherein at least one olefin having from 2 to 20 carbon atoms is contacted in a reaction zone at a temperature of from about 20° C. to about 250° C. and a pressure of from about 50 psig to about 800 psig
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- 5-SUBSTITUTED AND 5,7-DISUBSTITUTED 5,7-DIHYDRODIBENZOTHIEPINS AND THE CORRESPONDING S-OXYGENATED COMPOUNDS: ALKYLAMINES, CARBOXYLIC ACIDS, AND CARBOXAMIDES; SYNTHESIS AND PHARMACOLOGICAL SCREENING
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Reaction of 5,7-dihydrodibenzothiepin with n-butyllithium resulted in the partial sulfur extrusion and in the formation of the 9,10-dihydrophenanthrene-9-thiolate anion (B).Its further transformations (by hydrolysis, aminoalkylation and spontaneous dehydrogenation) led to phenanthrene-9-thiol (IX), the corresponding disulfide X, and the S-(2-dimethylaminoethyl) derivatives XI and XIV.Reactions of 5-chloro-5,7-dihydrodibenzothiepin (II) with the corresponding Grignard reagents were only a poor source of the amines III and IV.Reaction of the sulfoxide XVIII with n-butyllithium or with sodium hydride and the following treatment with 2-dimethylaminoethyl chloride gave the amine XIX in a low yield.Only the sulfone X was found more useful for preparing the 5- and 5,7-substituted derivatives.Treatment with n-butyllithium and following carbonation afforded mixtures of the monocarboxylic acid XXI and dicarboxylic acid XXVIII.Via acid chlorides they were transformed to the methylamides XXII and XXIX and to the dimethylamides XXIII and XXX.The amide XXIII was reduced to the 5-(dimethylaminomethyl) compound XXV.Lithiation of the sulfone XX or treatment with sodium hydride and the following action of 2-dimethylaminoethyl chloride and 3-dimethylaminopropyl chloride gave the amines XXVI, XXVII, and XXXI.Only the phenanthrene derivatives XI and XIV, and the amino sulfone XXVII showed clear indications of thymoleptic activity as potential antidepressants.
- Sindelar, Karel,Holubek, Jiri,Ryska, Miroslav,Koruna, Ivan,Protiva, Miroslav
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p. 2848 - 2868
(2007/10/02)
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- Oxidative Elimination Reactions, IV. - 5H-Dibenzazepine; Syntheses, Properties, Reactions
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5H-Dibenzazepine (1a) is easily accessible in crystalline form from 6,7-dihydro-5H-dibenzazepines having a leaving group (X=CH3SO2, NO2) at the heteroatom, via base-induced elimination of HX.The heterocyclic imine 1a is the thermodynamically stable form and shows no tendency to isomerize to the tautomeric 6H-dibenzazepine (1b) with an enamine moiety.The spectroscopic properties and the chemical reactions with electrophiles (e.g. alkyl halides and acid anhydrides) are in agreement with the imine structure, and confirm the theoretical predictions.
- Kreher, Richard,Gerhardt, Werner
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p. 240 - 247
(2007/10/02)
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- Studies toward Cyclic Trisulfides. Trisulfide Polymers and Sulfur Extrusion1
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Attempts were directed toward the synthesis of a variety of cyclic trisulfides, particularly by the reaction of N,N'-dibenzimidazolyl sulfide with dithiols.Only one monomeric cyclic trisulfide was prepared by this method; other cases yielded either mixtures of oligomers characterized as low molecular weight (5000) polymers or as products which spontaneously extruded sulfur to give the cyclic disulfides.We conlude that only where osmometric molecular weights or X-ray structures have been determined are monomeric cyclic trisulfides unambiguously defined.
- Harpp, David N.,Smith, Roger A.,Steliou, Kosta
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p. 2072 - 2079
(2007/10/02)
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- Intraanular phenyl-substituierte Phane - Synthese und dynamische Stereochemie
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The synthesis and properties of phanes of different ring size, substituted intraanularly by phenyl groups, and of new biphenylophanes 3, 38 - 43 with "pseudo-syn/anti"-structure are described.Barriers for the hindered rotation of intraanular phenyl substituents have been determined by D-NMR spectroscopy. syn/anti conformers of -, -, - and metacyclophanes are found.A better method for the preparation of mediocyclic bisdisulfides is reported.The pyrolysis of (2-biphenylyl)methyl sulfones leads to fluorenes; pyrolysis of the thiosulfonic S-ester 44 yields bibenzyl and dibenzyl sulfide.
- Boeckmann, Klaus,Voegtle, Fritz
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p. 1048 - 1064
(2007/10/02)
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