- Dinuclear gold(i) complexes bearing alkyl-bridged bis(n-heterocyclic carbene) ligands as catalysts for carboxylative cyclization of propargylamine: Synthesis, structure, and kinetic and mechanistic comparison to the mononuclear complex [Au(IPr)Cl]
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Eight new dinuclear gold(I) complexes, [Au2(L)X2] (1?8), were synthesized using a straightforward synthetic procedure under very mild conditions. The complexes have been characterized by NMR spectroscopy, elemental analysis, and single-crystal X-ray structure analysis. Their catalytic activity was investigated in the carboxylative cyclization of propargylamine (PPA). A superior performance in comparison to [Au(IPr)Cl] (9) was obtained for complexes 1 and 2 having an eight-methylene bridge connecting two NHCs with an arene bearing an isopropyl substituent for X = Cl, Br. This prompted more detailed kinetic and mechanistic studies by FTIR comparing dinuclear complex 2 of X = Cl to complex 9. Fortuitously the FTIR studies allowed monitoring of the formation of the products carbamic acid (CA) and carbamate salt (CS), as well as a key cyclized intermediate first discovered by Ikariya. These data allow additional insight into the mechanism as well as the central role which may be played by Au(I) carbamate formation as a higher energy resting state present in the catalytic cycle. The crystal structures of four of the new complexes and a detailed computational study relevant to the role of carbamic acid (CA) and carbamates in the catalytic cycle are also reported.
- Bayrakdar, Tahani A.C.A.,Nahra, Fady,Davis, Jack V.,Gamage, Mohan M.,Captain, Burjor,Temprado, Manuel,Marazzi, Marco,Saab, Marina,van Hecke, Kristof,Ormerod, Dominic,Hoff, Carl D.,Nolan, Steven P.
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- One-pot, two-step synthesis of 7-methylene-1,5-piperazine-fused 1,2,3-triazoles
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A facile, one-pot two-step synthesis of 7-methylene-1,5-piperazine-fused 1,2,3-triazole derivatives has been developed. The protocol employs an N-allylation of N-propargylated amines with 2,3-dibromopropene in the presence of K2CO3 in DMSO and a CuI-catalyzed [3 + 2] cycloaddition reaction of the synthetic N-(2-bromoallyl)-N-propargyl amines with sodium azide sequentially. Such a method provides methylene-substituted 1,2,3-triazole fused piperazines with some advantages such as simple operation, high efficiency and good product yield (80–91%) through readily available starting materials.
- Kuang, Lu,Ming, Peng,Wan, Chang-Feng,Chen, Jun-Min,Sheng, Shou-Ri
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p. 563 - 569
(2020/11/19)
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- Non-Noble-Metal Metal-Organic-Framework-Catalyzed Carboxylative Cyclization of Propargylic Amines with Atmospheric Carbon Dioxide under Ambient Conditions
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The coupling reaction of propargylic amines and carbon dioxide (CO2) to synthesize 2-oxazolidinones is an important reaction in industrial production, and yet harsh reaction conditions and noble-metal catalysts are often required to achieve high product yields. Herein, one novel noble-metal-free three-dimensional framework, [Mg3Cu2I2(IN)4(HCOO)2(DEF)4]n (1), assembled by magnesium and copper clusters was synthesized and applied to this reaction. Compound 1 displays excellent solvent stability. Importantly, 1, acting as heterogeneous catalyst, can highly catalyze the cyclization of propargylic amines with CO2 under atmospheric pressure at room temperature, which can be recycled at least five times without an obvious decrease of the catalytic activity. NMR spectroscopy, coupled with 13C-isotope- and deuterium-labeling experiments, clearly clarifies the mechanism of this catalytic system: CO2 was successfully captured and converted to the product of 2-oxazolidinones, the CC bond of propargylic amines can be effectively activated by 1, and proton transfer was involved in the reaction process. Density functional theory calculations are further conducted to uncover the reaction path and the crucial role of compound 1 during the reaction.
- Gu, Ai-Ling,Wang, Wan-Ting,Cheng, Xin-Yu,Hu, Tian-Ding,Wu, Zhi-Lei
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supporting information
p. 13425 - 13433
(2021/08/30)
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- Enantioselective Carboetherification/Hydrogenation for the Synthesis of Amino Alcohols via a Catalytically Formed Chiral Auxiliary
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Chiral auxiliaries and asymmetric catalysis are the workhorses of enantioselective transformations, but they still remain limited in terms of either efficiency or generality. Herein, we present an alternative strategy for controlling the stereoselectivity of chemical reactions. Asymmetric catalysis is used to install a transient chiral auxiliary starting from achiral precursors, which then directs diastereoselective reactions. We apply this strategy to a palladium-catalyzed carboetherification/hydrogenation sequence on propargylic amines, providing fast access to enantioenriched chiral amino alcohols, important building blocks for medicinal chemistry and drug discovery. All stereoisomers of the product could be accessed by the choice of ligand and substituent on the propargylic amine, leading to a stereodivergent process.
- Buzzetti, Luca,Puri??, Mikus,Greenwood, Phillip D. G.,Waser, Jerome
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supporting information
p. 17334 - 17339
(2020/11/02)
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- Palladium-Catalyzed Carbo-Oxygenation of Propargylic Amines using in Situ Tether Formation
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1,2-Amino alcohols and α-aminocarbonyls are frequently found in natural products, drugs, chiral auxiliaries, and catalysts. This work reports a new method for the palladium-catalyzed oxyalkynylation and oxyarylation of propargylic amines. The reaction is perfectly regioselective based on the in situ introduction of a hemiacetal tether derived from trifluoroacetaldehyde. cis-Selective carbo-oxygenation was achieved for terminal alkynes, whereas internal alkynes gave trans-carbo-oxygenation products. The obtained enol ethers could be easily transformed into 1,2-amino alcohols or α-amino ketones using hydrogenation or hydrolysis, respectively.
- Greenwood, Phillip D. G.,Grenet, Erwann,Waser, Jerome
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supporting information
p. 3010 - 3013
(2019/02/07)
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- Palladium-Catalyzed Carboxy-Alkynylation of Propargylic Amines Using Carbonate Salts as Carbon Dioxide Source
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A palladium-catalyzed multicomponent reaction of propargylic amines, alkynyl bromides and cesium hydrogen carbonate to access oxazolidinones is reported. In contrast to previous reports, only a slight excess of cesium hydrogen carbonate is used as a surrogate of carbon dioxide. The reaction gives access to oxazolidinones bearing alkyl- and aryl polysubstituted enynes in good yield and very high E stereoselectivity.
- Greenwood, Phillip D. G.,Waser, Jerome
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supporting information
p. 5183 - 5186
(2019/06/10)
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- Construction of the Oxazolidinone Framework from Propargylamine and CO2 in Air at Ambient Temperature: Catalytic Effect of a Gold Complex Featuring an L2/Z-Type Ligand
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The metal-catalyzed carboxylation of propargylamines with aerial CO2 at room temperature to form 5-methyleneoxazolidin-2-one derivatives has been developed. In this reaction, the catalyst [Au(dpbF)]X featuring a Z-type ligand gave the best results, presumably due to the σ-acceptance of the borane atom.
- Inagaki, Fuyuhiko,Maeda, Kakeru,Nakazawa, Kenta,Mukai, Chisato
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p. 2972 - 2976
(2018/06/27)
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- Lanthanide-Catalyzed Reversible Alkynyl Exchange by Carbon–Carbon Single-Bond Cleavage Assisted by a Secondary Amino Group
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Lanthanide-catalyzed alkynyl exchange through C?C single-bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β-alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo- and cross-dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions.
- Shao, Yinlin,Zhang, Fangjun,Zhang, Jie,Zhou, Xigeng
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supporting information
p. 11485 - 11489
(2016/10/24)
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- Synthesis of multiply substituted 1,6-dihydropyridines through Cu(I)-catalyzed 6-endo cyclization
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Copper-catalyzed 6-endo cyclization of N-propargylic β-enaminocarbonyls was developed for the synthesis of oxidation-labile 1,6-dihydropyridines. This synthetic method allows flexible and regio-defined assembly of various substituents at the N1, C2, C3, C4, and C6 positions of 1,6-dihydropyridines under mild conditions.
- Mizoguchi, Haruki,Watanabe, Ryo,Minami, Shintaro,Oikawa, Hideaki,Oguri, Hiroki
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supporting information
p. 5955 - 5963
(2015/06/08)
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- Highly regioselective synthesis of substituted isoindolinones via ruthenium-catalyzed alkyne cyclotrimerizations
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(Cyclooctadiene)(pentamethylcyclopentadiene) ruthenium chloride [Cp*RuCl (cod)] has been used to catalyze the regioselective cyclization of amide-tethered diynes with monosubstituted alkynes to give polysubstituted isoindolinones. Notably, the presence of a trimethylsilyl group on the diyne generally led to complete control over the regioselectivity of the alkyne cyclotrimerization. The cyclization reaction worked well in a sustainable non-chlorinated solvent and was tolerant of moisture. The optimized conditions were effective with a diverse range of alkynes and diynes. The 7-silylisoindolinone products could be halogenated, protodesilylated or ring opened to access a range of usefully functionalized products.
- Foster, Robert W.,Tame, Christopher J.,Hailes, Helen C.,Sheppard, Tom D.
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supporting information
p. 2353 - 2360
(2013/10/01)
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- NHC-Gold(I) complexes as effective catalysts for the carboxylative cyclization of propargylamines with carbon dioxide
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NHC-gold(I) complexes promote carboxylative cyclization of a range of propargylic amines to afford (Z)-5-alkylidene-1,3-oxazolidin-2-ones in methanol under neutral and mild conditions. The highly active and robust catalyst permits CO2 utilization under a mixed gas atmosphere containing CO or H 2. As a key intermediate, a new alkenylgold(I) complex was successfully identified from a stoichiometric reaction of Au(OH)(IPr) and 1-methylamino-2-butyne in THF. The methanol solvent influences the formation of catalytically active cationic gold species and facilitates protodeauration from the alkenylgold complex to release the cyclic urethane product due to in situ generation of methylcarbonic acid in the presence of CO2.
- Hase, Shun,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 5285 - 5288
(2013/11/06)
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- Rhodium-catalyzed synthesis of γ-butyrolactams and pyrrolidines via cycloisomerization of N-tethered 1,6-enynes
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A rhodium-catalyzed cycloisomerization reaction of N-tethered 1,6-enynes with an intramolecular halogen shift has been developed, providing a useful process for the synthesis of stereo defined γ-butyrolactam and pyrrolidine derivatives in good to excellent yields. Effects of both electronic feature and steric structure of the substrates on the outcome of the reaction were investigated.
- Wang, Jianping,Xie, Xiaomin,Ma, Fangfang,Peng, Zhiyong,Zhang, Lei,Zhang, Zhaoguo
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experimental part
p. 4212 - 4217
(2010/07/05)
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- Nickel-catalyzed carbocyanation of alkynes with allyl cyanides
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Allyl cyanides are found to add across alkynes in the presence of a nickel/P(4-CF3-C6H4)3 catalyst to give polysubstituted 2,5-hexadienenitriles with defined stereo- and regiochemistry. Use of AlMe2Cl or AlMe3 as a Lewis acid cocatalyst accelerates the reaction and expands the substrate scope significantly. The cyano group in the allylcyanation products can be transformed to a hydroxymethyl or aminomethyl group to afford highly substituted allylic alcohols or amines. α-Siloxyallyl cyanides also add across alkynes selectively at the less hindered γ-carbon to allow introduction of 3-oxo-propyl functionality after hydrolysis of the resulting silyl enol ethers. This particular carbocyanation reaction has been applied to the stereoselective construction of the trisubstituted double bond of plaunotol, an antibacterial natural product active against Helicobacter pylori.
- Hirata, Yasuhiro,Yukawa, Tomoya,Kashihara, Natsuko,Nakao, Yoshiaki,Hiyama, Tamejiro
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supporting information; experimental part
p. 10964 - 10973
(2009/12/03)
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- A convenient method for 3-pyrroline synthesis.
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[reaction: see text]. The synthesis of a range of 3-pyrrolines has been achieved from primary amine starting materials using a two-step alkylation/alkylidene carbene CH-insertion reaction sequence. We have shown that insertion into a range of CH-bond type
- Green,Prodger,Sherlock,Hayes
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p. 3377 - 3379
(2007/10/03)
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- Palladium catalysed tandem cyclisation - Anion capture processes. Part 2. Cyclisation onto alkynes or allenes with hydride capture
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A wide range of palladium catalysed regio- and stereo-specific 5-, 6- and 7-exo-dig mono-, bis- and tris-cyclisation processes or aryl and vinyl halides and allylic acetates are described. The mono- and bis-cyclisation processes terminate in hydride captu
- Grigg, Ronald,Loganathan, Vani,Sridharan, Visuvanathar,Stevenson, Paul,Sukirthalingam, Sukanthini,Worakun, Tanachat
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p. 11479 - 11502
(2007/10/03)
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- Rhodium-Catalysed Reactions of Propargylamines with CO/H2. Formation of Pyrroles and Butenolides
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Rhodium-catalysed reactions of (arylpropargyl)amines with CO/H2 give β-arylpyrroles in good yields.Reactions of (alkylpropargyl)amines gave alkylpyrroles together with butenolides which are formed in an unusual reaction that probably involves double carbonylation, reduction of one carbonyl function and removal of the amine function by hydrogenolysis.The single-crystal X-ray structure of 5-methyl-N,3-diphenylpyrrole-2-carboxamide is recorded.
- Campi, Eva M.,Fallon, Gary D.,Jackson, W. Roy,Nilsson, Ylva
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p. 1167 - 1178
(2007/10/02)
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