- Hydroamination of alkynes with aromatic amines catalyzed by digallane (dpp-bian)Ga—Ga(dpp-bian)
-
Digallane (dpp-bian)Ga—Ga(dpp-bian) (1) (dpp-bian is the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) catalyzes the addition of 4-chloroaniline to some terminal alkynes RC≡CH (R = Bun, Ph, 4-MeC6H4). The reaction orders in each of the substrates were found for the reaction of phenylacetylene with 4-chloroaniline catalyzed by compound 1. The reaction of compound 1 with phenylacetylene in a molar ratio of 1: 10 led to 1-[N-(2,6-diisopropylphenyl)imino]-2-(1-phenylethylidene)acenaphthene (5) and the compound [C12H6(NC6H3Pr2 i)(PhC=CH2)(PhC=CH)]Ga(C≡CPh)2 (6). The reaction of digallane 1 with phenylacetylene and aniline in a stoichiometric ratio of 1: 2: 2 gave bis-anilide (dpp-bian)-Ga[N(H)Ph]2 (7) in 40% yield. The compound (PhC≡C)3Ga·THF (9) was obtained by the reaction of three equivalents of sodium phenylacetylide (prepared in situ from phenylacetylene and sodium) with one equivalent of GaCl3 in tetrahydrofuran. Compounds 5—7 and 9 were characterized by IR spectroscopy, 1H NMR spectroscopy was used to characterize products 5, 6, and 9, whereas EPR spectroscopy was used for amide 7. The structures of compounds 5—7 and 9 were determined by single crystal X-ray diffraction analysis.
- Moskalev,Skatova,Chudakova,Khvoinova,Bazyakina,Morozov,Kazarina,Cherkasov,Abakumov,Fedushkin
-
-
Read Online
- Alkali Metal Ions Dictate the Structure and Reactivity of an Iron(II) Imido Complex
-
The presence of redox innocent metal ions has been proposed to modulate the reactivity of metal ligand multiple bonds; however, insight from structure/function relationships is limited. Here, alkali metal reduction of the Fe(III) imido complex [Ph2B(tBuIm
- Gao, Yafei,Pink, Maren,Smith, Jeremy M.
-
supporting information
p. 1786 - 1794
(2022/02/10)
-
- N,N-Chelate nickel(II) complexes bearing Schiff base ligands as efficient hydrogenation catalysts for amine synthesis
-
Five N, N-chelate nickel (II) complexes bearing N-(2-pyridinylmethylene)-benzylamine ligands with different substituent groups were synthesized in good yields. The nickel complexes exhibited prominent catalytic efficiency toward amine synthesis from nitro compounds by using NaBH4 or H2 as hydrogen source through two catalytic systems. Various amines with different substituents were obtained in moderate to excellent yields. All substrates with electron-donating and electron-withdrawing properties were tolerated in the two reduction systems. Given the efficient catalytic activity, broad substance scope, and mild reduction conditions, the nickel catalysts have potential applications in industrial production.
- Xu, Mengyin,Wang, Yang,Zhou, Yifeng,Yao, Zi-Jian
-
-
- Synthesis, Structure, and Catalytic Hydrogenation Activity of [NO]-Chelate Half-Sandwich Iridium Complexes with Schiff Base Ligands
-
A series of N,O-coordinate iridium(III) complexes with a half-sandwich motif bearing Schiff base ligands for catalytic hydrogenation of nitro and carbonyl substrates have been synthesized. All iridium complexes showed efficient catalytic activity for the hydrogenation of ketones, aldehydes, and nitro-containing compounds using clean H2 as reducing reagent. The iridium catalyst displayed the highest TON values of 960 and 950 in the hydrogenation of carbonyl and nitro substrates, respectively. Various types of substrates with different substituted groups afforded corresponding products in excellent yields. All N,O-coordinate iridium(III) complexes 1-4 were well characterized by IR, NMR, HRMS, and elemental analysis. The molecular structure of complex 1 was further characterized by single-crystal X-ray determination.
- Lv, Wen-Rui,Li, Rong-Jian,Liu, Zhen-Jiang,Jin, Yan,Yao, Zi-Jian
-
p. 8181 - 8188
(2021/05/26)
-
- Mild deprotection of the: N-tert -butyloxycarbonyl (N -Boc) group using oxalyl chloride
-
We report a mild method for the selective deprotection of the N-Boc group from a structurally diverse set of compounds, encompassing aliphatic, aromatic, and heterocyclic substrates by using oxalyl chloride in methanol. The reactions take place under room temperature conditions for 1-4 h with yields up to 90percent. This mild procedure was applied to a hybrid, medicinally active compound FC1, which is a novel dual inhibitor of IDO1 and DNA Pol gamma. A broader mechanism involving the electrophilic character of oxalyl chloride is postulated for this deprotection strategy. This journal is
- Awuah, Samuel G.,George, Nathaniel,Ofori, Samuel,Parkin, Sean
-
p. 24017 - 24026
(2020/07/23)
-
- Pyridylamido hafnium complexes with a silylene bridge: Synthesis and olefin polymerization
-
The synthesis and characterisation of six novel Cs-symmetric pyridylamido hafnium complexes with a silylene bridge of the type [ArPy(R2Si)NAr′]HfAlk2 are reported. Four complexes have been structurally characterised using single crystal X-ray diffraction. Appreciable differences between the solid state structures of these complexes and the pyridylamido hafnium complexes with a CRR′ bridge were noted. Reactions with B(C6F5)3, [Ph3C][B(C6F5)4] and [HMe2NPh][B(C6F5)4] yielded active catalysts for the homopolymerisations of propene and 1-hexene and ethene/1-octene copolymerization. In spite of the Cs-symmetry of the precatalysts, isotactically enriched polypropylene and poly(1-hexene) were obtained. The fact that the mechanism of the catalyst activation includes the insertion of alkene into the Hf-CAr bond was demonstrated. It was found that the structures of Ar and the R2Si bridge influence the activity, molecular weight capability and 1-octene affinity of the catalysts.
- Canich, Jo Ann M.,Hagadorn, John R.,Kulyabin, Pavel S.,Uborsky, Dmitry V.,Voskoboynikov, Alexander Z.
-
supporting information
p. 6693 - 6702
(2020/06/08)
-
- Copper catalyzed reduction of azides with diboron under mild conditions
-
We report herein the first Cu catalyzed reduction of azides with B2pin2 (pin = pinacolato) as the reductant under very mild conditions. A series of primary amines and amides were obtained in moderate to excellent yields with high chemoselectivity and good functional group tolerance. This reaction can be performed with a cheap copper salt, a simple NHC ligand and a diboron reagent.
- Chen, Yang,Deng, Shengqi,Gao, Yihua,Liu, Liwen,Liu, Yu,Lu, Da,Wang, Qianwen,Zhang, Xiao
-
supporting information
(2020/02/27)
-
- Commercially Available CuO Catalyzed Hydrogenation of Nitroarenes Using Ammonia Borane as a Hydrogen Source
-
Tandem ammonia borane dehydrogenation and nitroarenes hydrogenation has been reported as a novel strategy for the preparation of aromatic amines. However, the practical application of this strategy is subjected to the high-cost and tedious preparation of supported noble metal nanocatalysts. The commercially available CuO powder is herein demonstrated to be a robust catalyst for hydrogenation of nitroarenes using ammonia borane as a hydrogen source under mild conditions. Numerous amines (even sterically hindered, halogenated, and diamines) could be obtained through this method. This monometallic catalyst is characteristic of support-free, excellent chemoselectivity, low-cost, and high recyclability, which will favor its future utilization in preparative reduction chemistry. Mechanistic studies are also carried out to clarify that diazene and azoxybenzene are key intermediates of this heterogeneous reduction.
- Du, Jialei,Chen, Jie,Xia, Hehuan,Zhao, Yiwei,Wang, Fang,Liu, Hong,Zhou, Weijia,Wang, Bin
-
p. 2426 - 2430
(2020/03/30)
-
- KRAS G12C INHIBITORS AND METHODS OF USING THE SAME
-
Provided herein are KRAS G12C inhibitors, such as composition of the same, and methods of using the same. These inhibitors are useful for treating a number of disorders, including pancreatic, colorectal, and lung cancers.
- -
-
Paragraph 0885; 0887
(2019/12/30)
-
- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
-
A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
-
supporting information
p. 4781 - 4789
(2019/09/16)
-
- Catalytic hydrogenation of carbonyl and nitro compounds using an [: N, O] -chelate half-sandwich ruthenium catalyst
-
A series of N,O-chelate half-sandwich ruthenium complexes for both carbonyl and nitro compound hydrogenation have been synthesized based on β-ketoamino ligands. All complexes exhibited high activity for the catalytic hydrogenation of a series of ketones and nitroarenes with molecular H2 as the reducing reagent in aqueous medium. Consequently, the catalytic system showed the catalytic TON values of 950 for 1-phenylethanol in acetophenone hydrogenation and 1960 for 1-chloro-4-nitrobenzene in p-chloroaniline hydrogenation. Good catalytic activity was displayed for various kinds of substrates with either electron-donating or electron-withdrawing groups. The neutral ruthenium complexes 1-4 were fully characterized using NMR, IR, and elemental analysis. Molecular structures of complexes 2 and 4 were further confirmed using single-crystal X-ray diffraction analysis.
- Yao, Zi-Jian,Zhu, Jing-Wei,Lin, Nan,Qiao, Xin-Chao,Deng, Wei
-
p. 7158 - 7166
(2019/06/13)
-
- Intramolecular alkene hydroamination and degradation of amidines: Divergent behavior of rare earth metal amidinate intermediates
-
Direct N-H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.
- Zhang, Dexing,Liu, Ruiting,Zhou, Xigeng
-
p. 5573 - 5581
(2018/11/20)
-
- Absolute Estimates of PdII(n2-Arene) C-H Acidity
-
Thermodynamic acidity is one of the most widely used quantities for characterizing proton transfer reactions. Measurement of these values for catalytically relevant species can be challenging, often requiring direct observation of equilibria. The C-H bonds of aromatic substrates are proposed to become substantially polarized during electrophilic activation, but quantifying the absolute acidity of the intermediate M(n 2-arene) complexes is highly challenging. Using a system that intercepts nascent protons at electrophilic PdII arene complexes, a combined experimental and computational study has demonstrated these C-H bonds to be far more acidic (pKaCH3CN = 3-6) than many "nonbasic" substrates and additives that are present in electrophilic C-H activation catalysis, and the catalytic roles of these species may need to be reassessed.
- Christman, William E.,Morrow, Travis J.,Arulsamy, Navamoney,Hulley, Elliott B.
-
p. 2706 - 2715
(2018/09/10)
-
- Unlocking the potential of phenacyl protecting groups: CO2-based formation and photocatalytic release of caged amines
-
Orthogonal protection and deprotection of amines remain important tools in synthetic design as well as in chemical biology and material research applications. A robust, highly efficient, and sustainable method for the formation of phenacyl-based carbamate esters was developed using CO2 for the in situ preparation of the intermediate carbamates. Our mild and broadly applicable protocol allows for the formation of phenacyl urethanes of anilines, primary amines, including amino acids, and secondary amines in high to excellent yields. Moreover, we demonstrate the utility by a mild and convenient photocatalytic deprotection protocol using visible light. A key feature of the [Ru(bpy)3](PF6)2-catalyzed method is the use of ascorbic acid as reductive quencher in a neutral, buffered, two-phase acetonitrile/water mixture, granting fast and highly selective deprotection for all presented examples.
- Speckmeier, Elisabeth,Klimkait, Michael,Zeitler, Kirsten
-
p. 3738 - 3745
(2018/04/14)
-
- FE NANOPARTICLES WITH PPM CONTENTS OF PD, CU AND/OR NI, REACTIONS IN WATER CATALYZED BY THEM
-
The present application discloses a nanoparticle composition prepared from a mixture comprising: a) a transition metal salt; b) an iron salt; and c) a reducing agent; and methods for the use of such compositions, including the reduction of an organic compound comprising a nitro group to form an organic compound comprising an amine group, the Cu-catalyzed cyclization of an azide and an alkyne (click chemistry) and cross coupling reactions, notably Suzuki-Miyaura reactions. The transition metal salts are in particular Pd, Cu and Ni salts, the content of these metals being typically in the ppm range based on the major constituent Fe in the final products.
- -
-
Paragraph 0084; 0089
(2017/07/14)
-
- Novel ammonium ionic liquids as scavengers for aromatic and heterocyclic amines: Conversion into new pharmacological agents
-
The aim of our protocol is to develop new simple, economic and efficient scavengers for primary amines, due to their substantial adverse impacts on environment and human health. In this endeavor, we have designed, successfully synthesized and structurally characterized new salicylaldehyde-tri-nbutylammonium ionic liquids which were investigated as scavengers for diverse aromatic and heterocyclic primary amines in the synthesis of new pharmacologically relevant candidates, imines scavenging product, via Schiff-base-scavenging reaction. The new scavengers exhibited good capture efficiency and can be easily regenerated and reused. The advantages of our scavengers over polymer-supported scavengers are the simplicity, shorter reaction time and real-time monitoring of a model reaction. The biocidal and antitumor activities of the scavenging products revealed a moderate to excellent broad-spectrum antibacterial efficacy, low activity or inactivity as fungicides and different levels of cytotoxicity (weak to excellent) against human breast carcinoma (MCF-7) cells.
- Elshaarawy, Reda F.M.,Mokbel, Wafaa A.,El-Sawi, Emtithal A.
-
p. 1123 - 1132
(2016/09/28)
-
- Safe and Selective Nitro Group Reductions Catalyzed by Sustainable and Recyclable Fe/ppm Pd Nanoparticles in Water at Room Temperature
-
As a result of a unique synergy between ligand-free Fe/ppm Pd nanoparticles and PEG-containing designer surfactants, a facile and selective reduction of nitro-containing aromatics and heteroaromatics can be effected in water at room temperature in the presence of NaBH4. This new nanotechnology involves low catalyst loadings, is highly chemoselective, and tolerates a wide variety of functional groups. The process, which includes recycling of the entire aqueous medium, offers a general, environmentally responsible, and notably safe approach to highly valued reductions of nitro-containing compounds.
- Feng, Jie,Handa, Sachin,Gallou, Fabrice,Lipshutz, Bruce H.
-
supporting information
p. 8979 - 8983
(2016/07/26)
-
- Synthetic optimization and scale-up of imino-amido hafnium and zirconium olefin polymerization catalysts
-
Improved synthetic protocols were developed for the safe, efficient, and scalable preparation of imino-amido Hf and Zr complexes that are precatalysts for olefin polymerizations. Facile syntheses of four imino-amido complexes were achieved in high yields by direct reactions of 4 equiv of MeMgBr with mixtures of the corresponding bisimines or imine-amines and MCl4 (M = Hf, Zr). These synthetic routes eliminate the use of the pyrophoric reagents AlMe3 and n-BuLi used previously, avoid cryogenic conditions, and lead to significant yield improvements. Notably, competing reaction pathways between the bis-imine and MeLi were observed. This led to the discovery of the selective addition of MeMgBr to the bis-imine, which was successfully applied in the synthesis of the imine-amine ligand.
- Zhang, Chunming,Pan, Heqi,Klosin, Jerzy,Tu, Siyu,Jaganathan, Arvind,Fontaine, Philip P.
-
p. 1383 - 1391
(2015/11/03)
-
- Protonolysis and Amide Exchange Reactions of a Three-Coordinate Cobalt Amide Complex Supported by an N-Heterocyclic Carbene Ligand
-
A three-coordinate cobalt species, IPrCoCl{N-(SiMe3)2} [1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene], was synthesized by the reaction of {IPrCoCl2}2 with NaN(SiMe3)2. Compound 1 is a useful starting material for low-coordinate (IPr)Co species. 1 reacts with 2,6-di-tert-butyl-4-methylphenol (BHT-H) via aminolysis of the Co-N bond to generate a three-coordinate phenoxide complex, IPrCoCl(O-2,6-tBu2-4-MeC6H2) (2). The reaction of 1 with 2,6-diisopropylaniline (NH2DIPP) generates IPrCoCl(NHDIPP) (4), which undergoes disproportionation to form a mixture of 4, {IPrCoCl2}2, and IPrCo(NHDIPP)2 (3). The same product mixture is formed by the reaction of 1 with Li[NH(DIPP)], which unexpectedly proceeds by amide exchange. Compound 3 was synthesized independently by the reaction of {IPrCoCl2}2 with 4 equiv of Li[NH(DIPP)]. The reaction of 1 with the bulkier lithium 2,6-dimesitylanilide (LiNHDMP) also proceeds by amide exchange to generate IPrCoCl(NHDMP) (5), which is stable toward disproportionation. Compounds 1 and 2 exhibit trigonal-planar geometries at cobalt in the solid state. The solid-state structure of 3 also contains a trigonal-planar cobalt center and exhibits close Co---H contacts involving the methine hydrogen atoms of the NH(DIPP) groups in the axial positions. The solid-state structure of 5 features an interaction between cobalt and a flanking aryl group of the anilide ligand, resulting in pyramidalization of the cobalt center. (Chemical Equation Presented).
- Hansen, Christopher B.,Jordan, Richard F.,Hillhouse, Gregory L.
-
p. 4603 - 4610
(2015/05/27)
-
- Sulfide oxidation by O2: Synthesis, structure and reactivity of novel sulfide-incorporated Fe(II) bis(imino)pyridine complexes
-
The unsymmetrical iron(II) bis(imino)pyridine complexes [Fe II(LN3SMe)(H2O)3](OTf)2 (1), and [FeII(LN3-SMe)Cl2] (2) were synthesized and their reactivity with O2 was examined. Complexes 1 and 2 were characterized by single crystal X-ray crystallography, LDI-MS, 1H NMR and elemental analysis. The LN3SMe ligand was designed to incorporate a single sulfide donor and relies on the bis(imino)pyridine scaffold. This scaffold was selected for its ease of synthesis and its well-precedented ability to stabilize Fe(II) ions. Complexes 1 and 2 ware prepared via a metal-assisted template reaction from the unsymmetrical pyridyl ketone precursor 2-(O=CMe)-6-(2,6-(iPr 2-C6H3N=CMe)-C5H3N. Reaction of 1 with O2 was shown to afford the S-oxygenated sulfoxide complex [Fe(LN3S(O)Me)(OTf)]2+ (3), whereas compound 2, under the same reaction conditions, afforded the corresponding sulfone complex [Fe(LN3S(O2)Me)Cl]2+ (4).
- Widger, Leland R.,Siegler, Maxime A.,Goldberg, David P.
-
p. 179 - 189
(2013/07/26)
-
- Metal-free, stereospecific bis-silylation of functionalized alkynes with NHC-supported silylaminosilylene
-
The NHC-supported silylaminosilylene Ar(SiMe3)N(Cl)Si(IiPr) (1; Ar = 2,6-iPr2C6H3, IiPr = 1,3-diisopropyl-4,5- dimethylimidazol-2-ylidene) is an efficient and stereospecific bis-silylation reagent for a range of functionalized alkynes to yield cis-1,2-bis-silylated alkenes via a 1,4-silyl migration from the amino nitrogen atom to an alkyne carbon atom. The reaction is regio- and stereospecific for terminal alkynes with an electron-withdrawing substituent, thus providing a facile access to 1,2-bis-silylated alkenes with two different silyl groups.
- Cui, Haiyan,Ma, Bing,Cui, Chunming
-
p. 7339 - 7342
(2013/01/15)
-
- PROCESS FOR THE ALKYLATION OF ARYLAMINES
-
The present invention which provides an in situ process for preparing of a catalytically active complex for the alkylation of arylamines, a catalytically active complex mixture prepared by said process, a method for separately preparing a defined catalytically active complex out of the mixture of said in situ formed catalytically active complex, the use of said in situ or separately prepared catalytically active complex for the alkylation of arylamines, and a process in the alkylation of arylamines by using said in situ or separately prepared catalytically active complex and recycling said catalytically active complex in the reaction.
- -
-
Page/Page column 22; 27
(2011/02/24)
-
- β-carboxy sulfonamide ACAT inhibitors
-
β-Carboxy sulfonyl compounds of the formula STR1 wherein R1 is aryl, R3 is hydrogen or alkyl, R3 and R4 are hydrogen or alkyl, Y is --O--, --S--, or --NR2 --, and R5 is alkyl or aryl are potent inhibitors of the enzyme acyl CoA:cholesterol acyltransferase (ACAT) and are thus useful for treating hypercholesterolemia and atherosclerosis.
- -
-
-
- Hydrocarbons and chloroaromatics from anilines and n-butyl nitrite
-
A single reagent, i.e. n-butyl nitrite, can be used to oxidize an aromatic amine, or the corresponding N-methylene derivative, to a diazo compound followed by its subsequent reduction to hydrocarbon in a single batch.Alternatively, a chloro derivative can be obtained if carbon tetrachloride is used as the solvent.The reactions appear to be general and complete product identification was accomplished.
- Giumanini, Angelo G.,Verardo, Giancarlo,Gorassini, Fausto,Strazzolini, Paolo
-
p. 311 - 316
(2007/10/02)
-
- Isoxazolyl-substituted alkyl amide ACAT inhibitors
-
Pharmaceutically useful compounds having ACAT inhibitory activity of the formula STR1 wherein n is 0, 1, or 2, for X other than tetrazole and n=2 then R2 =R3 =H; R1 is phenyl, substituted phenyl, naphthyl, substituted naphthyl, a heteroaromatic group or a hydrocarbon group having from one to 18 carbon atoms; R2 and R3 are hydrogen, halo, hydroxy, alkyl, alkenyl, cycloalkyl, phenyl, substituted phenyl, a heteroaryl, or form a spiroalkyl group; X is a heteromonocyclic 5-membered ring containing one to four heteroatoms, said heteroatoms being nitrogen, oxygen or sulfur, and combination thereof; and R4 is a hydrocarbon group having from one to 20 carbon atoms are described as well as methods of their manufacture.
- -
-
-
- ELECTROCHEMICAL REDUCTION OF PRISTINAMYCIN IA AND RELATED STREPTOGRAMINS IN AQUEOUS ACIDIC MEDIUM
-
The electrochemical reduction of the picolinoyl residue of pristinamycinIA and related streptogramins was performed at a mercury cathode, in aqueous medium.The presence of a peptidic lactone residue at the amide nitrogen atom markedly modified the expected cathodic behaviour of pyridyl carboxamides: in particular, we observed the reduction of the pyridyl ring into tetrahydropyridine derivatives.Thanks to a series of model heterocyclic carboxamides, increasing steric hindrance at the amide nitrogen position was shown to lead to enhanced reduction of the heterocyclic ring.
- Largeron, M.,Vuilhorgne, M.,Potier, I. Le,Auzeil, N.,Bacque, E.,and al.
-
p. 6307 - 6332
(2007/10/02)
-
- Process for the isolation of alkylated aromatic amines
-
Alkylated aromatic amines can be isolated from crude catalyst-containing mixtures of these with olefins by a procedure in which in general equivalent amounts of an inorganic base and water are added to the alkylation mixture, the catalyst is hydrolysed, the water present in the reaction mixture after the hydrolysis is removed by distillation and the solid catalyst residue is separated off. The catalyst-free alkylation mixture which remains is then fed to customary further working up.
- -
-
-
- Preparation and properties of tantalum imido complexes and their reactions with alkynes. Coordination control through multiple metal-ligand bonding
-
The reaction of TaCl5 with Me3SiNHAr (NAr = N-2,6-C6H3-i-Pr2), in the presence of donor solvents, provides the imido complexes Ta(NAr)Cl3L2 (L = tetrahydrofuran (THF, 1), 1/2 dimethoxyethane (dme, 2), pyridine (py, 3), tetrahydrothiophene (THT, 4)) in high yield. These adducts are shown to exhibit a cis,mer geometry. The reaction of these compounds with 1 equiv of lithium alkoxides produces the imido alkoxide metathesis products Ta(NAr)(OR)Cl2L2 (5, OR = O-2,6-C6H3-i-Pr2 (DIPP), L = THF; 6, OR = DIPP, L = 1/2 dme; 7, OR = DIPP, L = py; 8, OR = O-2,6-C6H3Me2 (DMP), L = py). The reaction of Me3SiNEt2 with TaCl5 in toluene/diethyl ether gives a high yield of dimeric [Ta(NEt2)2Cl3]2 (9), from which the imido amide Ta(NAr)(NEt2)Cl2(py)2 (11) can be prepared by the reaction of 9 with LiNHAr. Dimeric 9 can be converted easily to the monomeric adduct Ta(NEt2)2Cl3(py) (10) upon reaction with pyridine. When these tantalum imides are reduced in the presence of alkynes, either alkyne adducts or metallacyclopentadienes are isolated. Thus, the compounds (EtC≡CEt)Ta(NAr)Cl(py)2 (12), (PhC≡CPh)Ta(NAr)Cl(py)2 (13), (Me3SiC≡CMe)Ta(NAr)Cl(py)2 (14), (C(CMe3)=CHCH=C(CMe3))Ta(NAr)Cl(py)2 (15), (EtC≡CEt)Ta(NAr)(DIPP)(py)2 (16), and (PrC≡CPr)Ta(NAr)(DIPP)(py)2 (17) are prepared from the two-electron reduction of either Ta(NAr)Cl3(py)2 (3) or Ta(NAr)(DIPP)Cl2(py)2 (7) in the presence of the appropriate alkyne. Crystals of the imido alkoxide Ta(N-2,6-C6H3-i-Pr2)(O-2,6-C6H 3Me2)Cl2(C5H5N) 2 (8) belong to the monoclinic space group P21/c with a = 9.547 (2) ?, b = 17.089 (3) ?, c = 19.135 (3) ?, β = 91.86 (1)°, and V = 3120.4 ?3 for Z = 4 with ρ(calcd) = 1.50 g/cm3. The X-ray structural study on 8 reveals a six-coordinate structure with cis-phenylimide and alkoxide ligands and mutually trans-chloride ligands. The imido linkage features a Ta-N bond of 1.769 (5) ? and Ta-N-Cipso angle of 179.1 (5)°, suggesting a Ta-N bond order between 2 and 3 and emphasizing the additional π donation of the nitrogen lone pair to an empty metal orbital. The phenoxide ligand is characterized by a Ta-O distance of 1.905 (5) ? and Ta-O-Cipso angle of 145.1 (5)°.
- Chao, Yuan-Wei,Wexler, Pamela A.,Wigley, David E.
-
p. 3860 - 3868
(2008/10/08)
-
- Revisitation of Formaldehyde Aniline Condensation. VIII. - Monomeric N-Methylene Anilines
-
A convenient, high yield "dry" method of synthesis of monomeric N-methyleneanilines (6a-i) and the characterization of the products by m.s., 1H- and 13C-n.m.r. and i.r. are reported, improving previous procedures and describing new compounds.It appeared that the existence of monomeric N-methyleneanilines is stricly related to the presence of enough steric hindrance to oligomerization by substituents in ortho positions.Moreover, some addition products of formaldehyde to an amine and its corresponding imines are tentatively identified on the basis of the observed mass spectrum of the whole reaction mixture.The reaction products of formaldehyde with 2,6-dimethylaniline (1a) provided an example of a mobile equilibrium between monomeric and trimeric imine.
- Giumanini, Angelo G.,Verardo, Giancarlo,Polana, Marco
-
p. 161 - 174
(2007/10/02)
-
- New diamines and a process for their production
-
New aminoalkyl anilines having the formula: STR1 wherein k is 0 or 1; QNH2 is a residue of formula STR2 which is situated in one of the positions of the benzene ring ortho or para to the amino group and wherein n is an integer from 1 to 15, R1 is C1 -C8 alkyl, R2 is C1 -C4 alkyl or R1 and R2, together with the carbon atom to which they are attached, form a C5 -C8 cycloalkylene residue, R3 is H or C1 -C6 alkyl, C3 -C8 cycloalkyl, or C6 -C10 aryl; and R4 and R5 are H or C1 -C4 alkyl; as well as the corresponding salts of compounds of formula I with organic or inorganic acids and metal salt complexes; process for their production; and their use as intermediates for polyamides.
- -
-
-
- Observation of a Stable Monomeric N-Methylene Aromatic Amine
-
The first free N-methyleneaniline stable under ordinary conditions was authenticated by spectroscopic and analytical data and some of its reactions were observed; a room temperature equilibrium between another free N-methylene aromatic amine and its oligomeric species is reported.
- Verardo, Giancarlo,Cauci, Sabina,Giumanini, Angelo G.
-
p. 1787 - 1788
(2007/10/02)
-
- Preparation of aromatic amines
-
Aromatic amines (anilines) are obtained directly or via the corresponding cycloaliphatic amines by an aminating/hydrogenating reaction of phenols with ammonia and hydrogen over a supported palladium catalyst which also contains elements from group 1b, 2b or 7b of the periodic table as well as iron, cobalt or nickel, as such or in the form of their compounds, and, preferably, an inorganic base, said catalysts also having dehydrogenating properties.
- -
-
-