7196-01-2Relevant articles and documents
Achieving Aliphatic Amine Addition to Arylalkynes via the Lewis Acid Assisted Triazole-Gold (TA-Au) Catalyst System
Jia, Teng,Fan, Shengyu,Li, Fengmian,Ye, Xiaohan,Zhang, Wenke,Song, Zhiguang,Shi, Xiaodong
supporting information, p. 6019 - 6023 (2021/08/03)
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.
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
Baron, Marco,Battistel, Edoardo,Tubaro, Cristina,Biffis, Andrea,Armelao, Lidia,Rancan, Marzio,Graiff, Claudia
, p. 4213 - 4223 (2018/11/23)
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.
Stereoselective Synthesis of a Highly Oxygenated δ-Lactone Related to the Core Structure of (-)-Enterocin
Wegmann, Marcus,Bach, Thorsten
supporting information, p. 209 - 217 (2016/12/24)
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.
SmI2(H2O)n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer
Kolmar, Scott S.,Mayer, James M.
supporting information, p. 10687 - 10692 (2017/08/15)
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.
Commercial Supported Gold Nanoparticles Catalyzed Alkyne Hydroamination and Indole Synthesis
Liang, Shengzong,Hammond, Luisa,Xu, Bo,Hammond, Gerald B.
supporting information, p. 3313 - 3318 (2016/10/21)
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.).
1,3-Dipolar cycloaddition reactivities of perfluorinated aryl azides with enamines and strained dipolarophiles
Xie, Sheng,Lopez, Steven A.,Ramstr?m, Olof,Yan, Mingdi,Houk
supporting information, p. 2958 - 2966 (2015/03/18)
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.
Supported Gold Nanoparticle-Catalyzed Hydration of Alkynes under Basic Conditions
Liang, Shengzong,Jasinski, Jacek,Hammond, Gerald B.,Xu, Bo
supporting information, p. 162 - 165 (2015/07/28)
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).
Copper-catalyzed hydroamination of alkynes with aliphatic amines: Regioselective access to (1 E,3 E)-1,4-disubstituted-1,3-dienes
Bahri, Janet,Jamoussi, Bassem,Van Der Lee, Arie,Taillefer, Marc,Monnier, Florian
supporting information, p. 1224 - 1227 (2015/03/14)
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.
Visible light-induced intermolecular radical addition: Facile access to γ-ketoesters from alkyl-bromocarboxylates and enamines
Hu, Bei,Chen, Haixia,Liu, Yan,Dong, Wuheng,Ren, Kai,Xie, Xiaomin,Xu, Hao,Zhang, Zhaoguo
supporting information, p. 13547 - 13550 (2015/01/09)
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.
Formal [4+2]-annulation of vinyl azides with N-unsaturated aldimines
Zhu, Xu,Wang, Yi-Feng,Zhang, Feng-Lian,Chiba, Shunsuke
supporting information, p. 2458 - 2462 (2014/10/15)
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.
