- Achieving Aliphatic Amine Addition to Arylalkynes via the Lewis Acid Assisted Triazole-Gold (TA-Au) Catalyst System
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Transition metal catalyzed intermolecular hydroamination of the arylalkynes with aliphatic amine is generally problematic due to the good coordination between amine and metal cation. With the combination of 1,2,3-triazole coordinated gold(I) catalyst (TA-Au) and Zn(OTf)2 cocatalyst, this challenging transformation was achieved with good to excellent yields and regioselectivity. Compared to previously reported methods, this approach offered an alternative catalyst system to achieve this fundamental chemical transformation with high efficiency and practical conditions.
- Jia, Teng,Fan, Shengyu,Li, Fengmian,Ye, Xiaohan,Zhang, Wenke,Song, Zhiguang,Shi, Xiaodong
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supporting information
p. 6019 - 6023
(2021/08/03)
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- Single-Step Synthesis of Dinuclear Neutral Gold(I) Complexes with Bridging Di(N-heterocyclic carbene) Ligands and Their Catalytic Performance in Cross Coupling Reactions and Alkyne Hydroamination
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We report on a single-step procedure for the synthesis of dinuclear gold(I) complexes with bridging di(N-heterocyclic carbene) (diNHC) ligands of general formula Au2Br2L1-9 (L = diNHC). The obtained complexes differ in the bridging group between the carbene donors and in the terminal wingtip substituents at the imidazol-2-ylidene rings. The complexes have been characterized by means of elemental analysis, NMR spectroscopy, ESI-MS spectrometry, and single-crystal X-ray structure analysis. The dinuclear gold(I) complexes have been tested as homogeneous catalysts in technologically relevant reactions such as the cross coupling between phenylboronic acid and aryl bromides and the intermolecular hydroamination of alkynes. The catalytic performance has been compared for complexes Au2Br2L1-9 and the benchmark mononuclear complex IPrAuCl.
- Baron, Marco,Battistel, Edoardo,Tubaro, Cristina,Biffis, Andrea,Armelao, Lidia,Rancan, Marzio,Graiff, Claudia
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p. 4213 - 4223
(2018/11/23)
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- Stereoselective Synthesis of a Highly Oxygenated δ-Lactone Related to the Core Structure of (-)-Enterocin
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The title compound was prepared in a concise route starting from an appropriately protected (S)-glyceraldehyde. A highly diastereoselective (d.r. >95:5) Mukaiyama aldol reaction of an acetoacetate-derived silyl enol ether served as the initial step of the synthetic sequence. It was found that protection of the glyceraldehyde as a butane-2,3-dione acetal is required to achieve the desired diastereoselectivity. Upon lactonization, a Tsuji-Trost allylation and a subsequent one-pot reaction cascade including an ozonolysis and an α-hydroxylation gave diastereoselective access to the desired α-hydroxy-β-oxo-δ-lactone. Alternative synthetic approaches are discussed and proof for the configuration of the product is presented.
- Wegmann, Marcus,Bach, Thorsten
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supporting information
p. 209 - 217
(2016/12/24)
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- SmI2(H2O)n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer
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Samarium diiodide in the presence of water and THF (SmI2(H2O)n) has in recent years become a versatile and useful reagent, mainly for reducing carbonyl-type substrates. This work reports the reduction of several enamines by SmI2(H2O)n. Mechanistic experiments implicate a concerted proton-coupled electron transfer (PCET) pathway, based on various pieces of evidence against initial outer-sphere electron transfer, proton transfer, or substrate coordination. A thermochemical analysis indicates that the C-H bond formed in the rate-determining step has a bond dissociation free energy (BDFE) of ~32 kcal mol-1. The O-H BDFE of the samarium aquo ion is estimated to be 26 kcal mol-1, which is among the weakest known X-H bonds of stable reagents. Thus, SmI2(H2O)n should be able to form very weak C-H bonds. The reduction of these highly electron rich substrates by SmI2(H2O)n shows that this reagent is a very strong hydrogen atom donor as well as an outer-sphere reductant.
- Kolmar, Scott S.,Mayer, James M.
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supporting information
p. 10687 - 10692
(2017/08/15)
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- Commercial Supported Gold Nanoparticles Catalyzed Alkyne Hydroamination and Indole Synthesis
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Commercial gold nanoparticles supported on titanium dioxide (TiO2) were found to be a highly efficient catalyst for alkyne hydroamination. Terminal alkynes could easily undergo intermolecular hydroamination with low catalyst loadings (0.2 mol% Au) under solvent-free conditions. Indoles were efficiently synthesized using microwave heating through intramolecular hydroamination. (Figure presented.).
- Liang, Shengzong,Hammond, Luisa,Xu, Bo,Hammond, Gerald B.
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supporting information
p. 3313 - 3318
(2016/10/21)
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- 1,3-Dipolar cycloaddition reactivities of perfluorinated aryl azides with enamines and strained dipolarophiles
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The reactivities of enamines and predistorted (strained) dipolarophiles toward perfluoroaryl azides (PFAAs) were explored experimentally and computationally. Kinetic analyses indicate that PFAAs undergo (3 + 2) cycloadditions with enamines up to 4 orders of magnitude faster than phenyl azide reacts with these dipolarophiles. DFT calculations were used to identify the origin of this rate acceleration. Orbital interactions between the cycloaddends are larger due to the relatively low-lying LUMO of PFAAs. The triazolines resulting from PFAA-enamine cycloadditions rearrange to amidines at room temperature, while (3 + 2) cycloadditions of enamines and phenyl azide yield stable, isolable triazolines. The 1,3-dipolar cycloadditions of norbornene and DIBAC also show increased reactivity toward PFAAs over phenyl azide but are slower than enamine-azide cycloadditions.
- Xie, Sheng,Lopez, Steven A.,Ramstr?m, Olof,Yan, Mingdi,Houk
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supporting information
p. 2958 - 2966
(2015/03/18)
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- Supported Gold Nanoparticle-Catalyzed Hydration of Alkynes under Basic Conditions
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TiO2-supported nanosize gold particles catalyze the hydration of alkynes using morpholine as a basic cocatalyst. Unlike most homogeneous cationic gold catalysts, the TiO2-Au/morpholine system is weakly basic and is compatible with acid-sensitive functional groups (e.g., silyl ethers, ketals) or with a strongly coordinating group such as pyridine. What's more, this gold catalyst can be recycled by simple filtration and works well in flow reactors. (Chemical Equation Presented).
- Liang, Shengzong,Jasinski, Jacek,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 162 - 165
(2015/07/28)
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- Copper-catalyzed hydroamination of alkynes with aliphatic amines: Regioselective access to (1 E,3 E)-1,4-disubstituted-1,3-dienes
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Copper-catalyzed hydroamination of aromatic or heteroaromatic alkynes with cyclic secondary aliphatic amines undergoes generation of an enamine-type intermediate. The latter is transformed in situ via a coupling reaction with a second molecule of alkyne to afford regioselectively (1E,3E)-1,4-disubstituted-1,3-dienes with the formation of C-N, C-C, and C-H bonds.
- Bahri, Janet,Jamoussi, Bassem,Van Der Lee, Arie,Taillefer, Marc,Monnier, Florian
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supporting information
p. 1224 - 1227
(2015/03/14)
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- Visible light-induced intermolecular radical addition: Facile access to γ-ketoesters from alkyl-bromocarboxylates and enamines
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A highly efficient addition of alkyl α-bromocarboxylates to enamines by visible light-induced photoredox catalysis is reported. Compared with traditional methods, the reaction described here provided an alternative route for the construction of valuable γ-ketoesters in generally good yields.
- Hu, Bei,Chen, Haixia,Liu, Yan,Dong, Wuheng,Ren, Kai,Xie, Xiaomin,Xu, Hao,Zhang, Zhaoguo
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supporting information
p. 13547 - 13550
(2015/01/09)
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- Formal [4+2]-annulation of vinyl azides with N-unsaturated aldimines
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Highly functionalized quinolines and pyridines could be synthesized by BF3?OEt2-mediated reactions of vinyl azides with N-aryl and N-alkenyl aldimines, respectively. The reaction mechanism could be characterized as formal [4+2]-annulation, including unprecedented enamine-type nucleophilic attack of vinyl azides to aldimines and subsequent nucleophilic cyclization onto the resulting iminodiazonium ion moieties.
- Zhu, Xu,Wang, Yi-Feng,Zhang, Feng-Lian,Chiba, Shunsuke
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supporting information
p. 2458 - 2462
(2014/10/15)
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- Visible light induced photocatalytic conversion of enamines into amides
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A series of enamines were photocatalytically cleaved to produce amide products under simple visible-light irradiation from a 45 W household light bulb. Mechanistically, the reactions appear to involve photosensitized formation of a singlet oxygen intermediate and a subsequent [2+2] cycloaddition event. Georg Thieme Verlag Stuttgart, New York.
- Li, Jing,Cai, Shunyou,Chen, Jietao,Zhao, Yaohong,Wang, David Zhigang
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supporting information
p. 1626 - 1628
(2014/07/08)
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- Synthesis of β-arylacyl / β-heteroarylacyl-β-alkylidene malonates and their application in substituted pyridone synthesis
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A novel approach has been developed for the synthesis of β-arylacyl/β-heteroarylacyl-β-alkylidine malonates in moderate to good yields by the reaction of Stork aryl and heteroaryl enamine with β-chloroalkylidene malonates. The reaction involves conjugate
- Wagh, Manoj Balu,Shankar,Mini,Krishnamohan,Madhubabu,Pal, Abir K.,Jayaprakash, Sarva,Krishna,Dahanukar, Vilas,Kumar, U. K. Syam,Gill
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- N -(4-cyanotetrahydro-2 H -pyran-4-yl) and N -(1-cyanocyclohexyl) derivatives of 1,5-diarylpyrazole-3-carboxamides showing high affinity for 18 kDa translocator protein and/or cannabinoid receptors
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In order to develop improved radioligands for imaging brain CB1 receptors with positron emission tomography (PET) based on rimonabant (5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-N-(piperidin-1-yl) -1H-pyrazole-3-carboxamide, 1), we synt
- Donohue, Sean R.,Dannals, Robert F.,Halldin, Christer,Pike, Victor W.
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experimental part
p. 2961 - 2970
(2011/06/24)
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- Asymmetrie copper-catalyzed propargylic substitution reaction of propargylic acetates with enamines
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Enamines served as carbon-nucleophiles for the first time In the Cu-catalyzed asymmetric propargylic substitution reaction of propargylic acetates, providing corresponding chiral β-ethynyl-substituted ketones In high yields and In good to high enantioselectivity.
- Fang, Ping,Hou, Xue-Long
-
supporting information; experimental part
p. 4612 - 4615
(2009/12/09)
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- (t-Bu)2PN=P(i-BuNCH2CH2)3N: New efficient ligand for palladium-catalyzed C-N couplings of aryl and heteroaryl bromides and chlorides and for vinyl bromides at room temperature
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(Chemical Equation Presented) By employing Pd(OAc)2, Cs 2CO3, or NaOH, and the new ligand (t-Bu) 2PN=P(i-BuNCH2CH2)3N (3a), an electronically diverse array of aryl bromides and chlorides possessing base-sensitive substituents (nitro, ester, and keto) provide coupling products with bulky aryl amines in good to excellent yields. Aryl halides possessing other functional groups including cyano, amino, trifluoromethyl, and phenol, coupled with equal ease, producing highly functionalized amines in good to excellent yields. Moreover, an aryl chloro group can be preserved in the presence of a bromo substituent under our reaction conditions. BOC-protected amines also participated efficiently. Heterocyclic bromides and chlorides underwent clean couplings with amines in excellent yields. An important strength of our protocol is the use of lower palladium loadings than those reported earlier, without compromising yields. The air-stable palladium complex (η3-cinnamyl)PdCl·(3a) (5) was also employed successfully in C-N coupling reactions while the crotyl analogue was less efficacious. The 3a/Pd(OAc)2 catalyst system promotes, for the first time, efficient coupling of vinyl bromides with a variety of amines to produce imines and enamines at room temperature.
- Reddy, Ch. Venkat,Kingston, Jesudoss V.,Verkade, John G.
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p. 3047 - 3062
(2008/09/19)
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- New, general, and practical enamine cyclopropanation using dichloromethane
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Dichloromethane serves as a novel electrophilic carbene equivalent which adds to an enamine double bond. The presence of other alkene moieties in the enamine partner is well tolerated. Even enamines derived from sterically hindered ketones react readily with dichloromethane promoted by TiCl 4-Mg.
- Tsai, Chia-Chung,Hsieh, I.-Lin,Cheng, Tsung-Ting,Tsai, Ping-Kuei,Lin, Kuo-Wei,Yan, Tu-Hsin
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p. 2261 - 2263
(2007/10/03)
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- A highly effective catalyst system for the Pd-catalyzed amination of vinyl bromides and chlorides
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(Chemical Equation Presented) A highly efficient synthesis of enamines and imines by Pd-catalyzed amination of vinyl bromides or chlorides with amines is described using the Pd2(dba)3/P(i-BuNCH2CH 2)3N catalyst system.
- Reddy, Chinta Reddy Venkat,Urgaonkar, Sameer,Verkade, John G.
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p. 4427 - 4430
(2007/10/03)
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- Synthesis of enamines using easily prepared silica gel supported sulfuric acid catalyst
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A variety of enamines are easily and efficiently synthesised in short reaction times and moderate to high yields from corresponding acyclic and cyclic ketones using sulfuric acid-silica catalyst.
- Bigdeli, Mohammad Ali,Nikje, Mir Mohammad Alavi,Gorji, Banafshe,Moghimi, Aboulghasem
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p. 800 - 801
(2007/10/03)
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- New reaction of enamines with aryldiazoacetates catalyzed by transition metal complexes
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The reaction of aryldiazoacetates with enamines catalyzed by copper and rhodium complexes provided γ-keto esters in good yields. A full investigation of the effects of solvents, catalysts, enamines and aryldiazoacetates on the reaction was carried out. Careful analysis of the crude reaction mixture revealed a substituted enamine as the primary product, which was hydrolyzed over silica gel to give a γ-keto ester as the final product. A reaction mechanism involving nucleophilic addition of an enamine to a metal carbene and subsequent hydrogen transfer was proposed. Chiral dirhodium and copper catalysts were examined and found to provide γ-keto esters with no enantioselectivity. The result could be rationalized based on the proposed reaction mechanism. Attempts to trap the enamine intermediate with several electrophilic reagents were not successful.
- Zhao, Wei-Jie,Yan, Ming,Huang, Dan,Ji, Shun-Jun
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p. 5585 - 5593
(2007/10/03)
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- Reactions of enamines with selectfluor: A straightforward route to difluorinated carbonyl compounds
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Reactions of enamines, preformed from β-dicarbonyl and monocarbonyl compounds, with Selectfluor (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2] octane bis(tetrafluoroborate) under mild conditions (triethylamine (TEA) or molecular sieves) easily led to the corresponding difluorinated carbonyl compounds in high yields.
- Peng, Weimin,Shreeve, Jean'ne M.
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p. 5760 - 5763
(2007/10/03)
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- Palladium-Catalyzed Cross-Coupling Reactions of Amines with Alkenyl Bromides: A New Method for the Synthesis of Enamines and Imines
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The palladium-catalyzed cross-coupling reaction of alkenyl bromides with secondary and primary amines gives rise to enamines and imines, respectively. This new transformation expands the applicability of palladium-catalyzed C-N bond forming reactions (the Buchwald-Hartwig amination), which have mostly been applied to aryl halides. After screening of different ligands, bases, and solvents, the catalytic combination [Pd2(dba)3]/BINAP in the presence of NaOtBu in toluene gave the best results in the cross-coupling of secondary amines with 1-bromostyrene (dba=dibenzylideneacetone, BINAP=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl). The corresponding enamines are obtained cleanly and in nearly quantitative yields. However, steric hindrance seems to be a limitation of the reaction, as amines carrying large substituents are not well converted. The same methodology can be applied to the coupling of secondary amines with 2-bromostyrene. Moreover, the reaction with substituted 2-bromopropenes allows regioselective synthesis of isomerizable terminal enamines without isomerization of the double bond. The best catalytic conditions for the cross-coupling of 1-bromostyrene with primary amines include again the use of the Pd°/BINAP/NaOtBu system. The reaction gives rise to the expected imines in very short times and with low catalyst loadings. A set of structurally diverse imines can be prepared by this methodology through variations in the structure of both coupling partners. However, 2-bromostyrene failed to give good results in this coupling reaction, probably due to product inhibition of the catalytic cycle. Competition experiments of vinyl versus aryl amination reveal that the reaction occurs preferentially on vinyl bromides.
- Barluenga, Jose,Fernandez, M. Alejandro,Aznar, Fernando,Valdes, Carlos
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p. 494 - 507
(2007/10/03)
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- Palladium catalyzed animation of vinyl chlorides: A new entry to imines, enamines and 2-amino-1,3-butadienes
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Vinyl chlorides are employed for the first time in palladium catalyzed cross-coupling reactions with amines to furnish imines and enamines. The new methodology has been applied to the synthesis of 2-amino-1,3-butadienes, that could not be achieved from th
- Barluenga, Jose,Fernandez, M. Alejandro,Aznar, Fernando,Valdes, Carlos
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p. 1400 - 1401
(2007/10/03)
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- Novel method for the synthesis of enamines by palladium catalyzed amination of alkenyl bromides
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The intermolecular palladium catalyzed cross-coupling reaction between secondary amines and alkenyl bromides is described for the first time, giving rise to enamines with very high yields and regioselectivity.
- Barluenga, Jose,Fernandez, M. Alejandro,Aznar, Fernando,Valdes, Carlos
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p. 2362 - 2363
(2007/10/03)
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- Lanthanoid(III) Trichloride-Tin(II) Chloride mediated Cycloaddition Reaction of α,α'-Dibromo Ketones with 1,3-Dienes or Enamines
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The reaction of α,α'-dibromo ketones with 1,3-dienes in the presence of CeCl3-SnCl2 in tetrahydrofuran is found to give the corresponding cycloadduct in fair to good yields under mild conditions.Furan and cyclopentadiene serve as highly efficient receptors of the oxallyl intermediate to give bicyclic cycloadducts.The reaction of 2,4-dibromo-3-pentanone with isoprene gives both and cycloadducts. Cycloaddition proceeds similarly with enamines to afford 2-cyclopenten-1-ones after treatment with 3percent ethanolic NaOH solution.
- Fukuzawa, Shin-ichi,Fukushima, Masakazu,Fujinami, Tatsuo,Sakai, Shizuyoshi
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p. 2348 - 2352
(2007/10/02)
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- Carbonyl Methylenation Using a Titanium- Aluminum (Tebbe) Complex
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The titanium-aluminum (Tebbe) complex is shown to be an effective methylenating agent for a variety of carbonyl groups.The reaction is unique in that the carbonyl groups of carboxylic acid derivatives are readily methylenated.Thus vinyl enol ethers are prepared from esters and enamines are formed from amides.The complex provides a method for methylenating hindered or base sensitive ketones that is advantageous to the Wittig reagent.Selective methylenation of dicarbonyl compounds is also accomplished.
- Pine, Stanley H.,Pettit, Robert J.,Geib, Gregory D.,Cruz, Susana G.,Gallego, Claudio H.,et al.
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p. 1212 - 1216
(2007/10/02)
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- Enamine synthesis using the Horner-Wittig reaction. Part 2. New acyl anion equivalents derived from (aminomethyl)diphenylphosphine oxides
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Using the Horner-Wittig reagents (1-morpholino-alkyl)diphenylphosphine oxides (1), aromatic as well as aliphatic α,β-unsaturated aldehydes can be converted into the morpholino enamines of their respective homologous phenyl, ethyl and styryl ketones.These enamines can be easily converted into the corresponding ketones by mild, acid-catalyzed hydrolysis.The usefulness of these phosphine oxides as acyl anion equivalents is further demonstrated by the synthesis of dihydrojasmone and of (Z)-6-henicosen-11-one.
- Broekhof, N. L. J. M.,Elburg, P. van,Hoff, D. J.,Gen, A. van der
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p. 317 - 321
(2007/10/02)
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- Improved Titanium Tetrachloride Procedure for Enamine Synthesis.II.Scope of the Reaction
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The scope of enamine formation by a procedure where the carbonyl compound is added to a preformed titanium tetrachloride-amine complex was investigated with a series of different types of carbonyl compounds and two secondary amines (morpholine and pyrrolidine).The carbonyl compounds include aldehydes, cyclic ketones and some substituted aryl alkyl ketones.Yields of isolated products were in the range 67-100 percent with the exception of the pyrrolidine enamine from camphor which gave 53 percent of the isolated product.
- Carlson, Rolf,Nilsson, Asa
-
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- NEW SYNTHETIC APPROACHES TO 4(1H)-PYRIDINONE DERIVATIVES THE SYNTHESIS OF 3-ACYL-4-(1H)-PYRIDINONES
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The synthesis of 3-alkanoyl and 3-benzoylpyridin-4-ones is described from 1,3-diketones (5,11) or their equivalents.A novel Ca'-acylation of enaminones is described.
- Abdulla, Riaz F.,Morgan, Lawrence A.,Williams, James C.
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p. 2189 - 2195
(2007/10/02)
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- Alkynylmercury Chloride or Acetate as Intermediates in the Mercury(II) Salt-promoted Addition of Aliphatic and Aromatic Amines to Terminal Acetylenes
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Arylaminomercuriation of terminal acetylenes has been carried out with aliphatic amines to yield amines and enamines.Phenylethynylmercury chloride is shown to be an intermediate in the mercury(II) salt-promoted addition of aliphatic and aromatic amines to terminal alkynes.
- Barluenga, Jose,Aznar, Fernando,Liz, Ramon,Rodes, Rosa
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p. 1087 - 1091
(2007/10/02)
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- The Chemistry of Aryllead(IV) Tricarboxylates. Reaction with Enamines
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The treatment of 1-morhpholinocyclopentene (1a) with p-methoxyphenyllead triacetate (2a) in chloroform provides a simple high-yielding route to 2-(4-methoxyphenyl)cyclopentanone (3a).This arylation reaction of enamines has been investigated with a variety of substrates and a number of aryllead triacetates.The reaction has been found to be very sensitive to steric effects and is thus a useful synthetic method in a relatively small number of cases.Acetoxylation is a major competing reaction with those enamines of cyclic ketones which give a low to moderate yield of arylated product.
- May, George L.,Pinhey, John T.
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p. 1859 - 1871
(2007/10/02)
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- CHARGE TRANSFER COMPLEXES OF 3,3',5,5'-TETRAPHENYL-2,2'-DITHIODIPYRANYLIDINE(2,2'DIPSΦ4) WITH 7,7',8,8'-TETRACYANOQUINODIMETHANE(TCNQ) AND IODINE
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New charge transfer complexes pf 2,2'DIPSΦ4 with TCNQ and iodine have high conductivity at room temperature.VSC measurements showed a broad maximum centered at 273 K and a large narrow maximum centered at 273 K for 1:1, 1:2 TCNQ complexes respectively.
- Tao-pen, Chu,Meixiang, Wan,Mingzhu, Li,Dian, Guo,Renyuan, Qian
-
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- SYNTHESIS AND PROPERTIES OF SOME β-TRIORGANOSILYLENAMINES
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Ten β-triorganosilyl-substituted enamines were synthesized by the silylation of β-lithioenamines.They are thermally stable oils but are easily desilylated with protic compounds to give the parent enamines.
- Kuno, Suzumitsu,Sato, Yoshiro
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p. 309 - 314
(2007/10/02)
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