70028-10-3Relevant academic research and scientific papers
Synthesis of Chiral Bifunctional NHC Ligands and Survey of Their Utilities in Asymmetric Gold Catalysis
Liu, Yunkui,Wang, Xing-Wang,Zhang, Jun-Qi,Zhang, Liming
, (2019)
The synthesis and characterization of the chiral bifunctional NHC ligands based on the imidazo[1,5-a]pyridine (ImPy) scaffold are described. These ligands possess a fluxional biaryl axis and a chiral center. The configurational stability of the biaryl axis in their gold(I) complexes is investigated. The application of these axially chiral ImPy-based AuCl complexes in a series of gold catalysis is explored, and varying degrees of asymmetric induction are observed. In most cases, the ligand (aS,R)-L8-H with its cyclohexyl group pointing to the reaction site and hence exerting asymmetric steric influence is more effective in asymmetric induction.
Microwave-assisted direct addition of cycloethers to alkynes
Zhang, Yuhua,Li, Chao-Jun
, p. 7581 - 7584 (2004)
Under microwave conditions, tetrahydrofuran (THF), tetrahydropyran and 1,4-dioxane are added directly onto alkynes and generated various vinyl cycloethers.
Direct, Site-Selective and Redox-Neutral α-C?H Bond Functionalization of Tetrahydrofurans via Quantum Dots Photocatalysis
Chen, Bin,Ci, Rui-Nan,Huang, Cheng,Liu, Zan,Qiao, Jia,Song, Zi-Qi,Tung, Chen-Ho,Wu, Li-Zhu
supporting information, p. 27201 - 27205 (2021/11/16)
As one of the most ubiquitous bulk reagents available, the intrinsic chemical inertness of tetrahydrofuran (THF) makes direct and site-selective C(sp3)?H bond activation difficult, especially under redox neutral condition. Here, we demonstrate that semiconductor quantum dots (QDs) can activate α-C?H bond of THF via forming QDs/THF conjugates. Under visible light irradiation, the resultant alkoxyalkyl radical directly engages in radical cross-coupling with α-amino radical from amino C?H bonds or radical addition with alkene or phenylacetylene, respectively. In contrast to stoichiometric oxidant or hydrogen atom transfer reagents required in previous studies, the scalable benchtop approach can execute α-C?H bond activation of THF only by a QD photocatalyst under redox-neutral condition, thus providing a broad of value added chemicals starting from bulk THFs reagent.
Phenylglyoxylic Acid: An Efficient Initiator for the Photochemical Hydrogen Atom Transfer C?H Functionalization of Heterocycles
Papadopoulos, Giorgos N.,Kokotou, Maroula G.,Spiliopoulou, Nikoleta,Nikitas, Nikolaos F.,Voutyritsa, Errika,Tzaras, Dimitrios I.,Kaplaneris, Nikolaos,Kokotos, Christoforos G.
, p. 5934 - 5944 (2020/09/09)
C?H functionalization at the α-position of heterocycles has become a rapidly growing area of research. Herein, a cheap and efficient photochemical method was developed for the C?H functionalization of heterocycles. Phenylglyoxylic acid (PhCOCOOH) could behave as an alternative to metal-based catalysts and organic dyes and provided a very general and wide array of photochemical C?H alkylation, alkenylation, and alkynylation, as well as C?N bond forming reaction methodologies. This novel, mild, and metal-free protocol was successfully employed in the functionalization of a wide range of C?H bonds, utilizing not only O- or N-heterocycles, but also the less studied S-heterocycles.
Photoredox Oxo-C(sp3)-H Bond Functionalization via in Situ Cu(I)-Acetylide Catalysis
Song, Zi-Qi,Liu, Zan,Gan, Qi-Chao,Lei, Tao,Tung, Chen-Ho,Wu, Li-Zhu
supporting information, p. 832 - 836 (2020/01/31)
A unified strategy for the synthesis of 2-vinyl heterocycles is reported. With visible light irradiation, simple and cheap CuCl is able to functionalize a terminal alkyne, giving Cu(I)-acetylide in situ. Unlike the case of noble metals or organic dye photocatalysts, this critical Cu(I)-acetylide not only activates the C-H bond of terminal alkynes but also serves as a photocatalyst to achieve varieties of 2-vinyl heterocycles in good to excellent yields, even for large scale and late-stage functionalization of natural product.
Decarboxylative Hydroalkylation of Alkynes via Dual Copper-Photoredox Catalysis
Ca?ellas, Santiago,Caldentey, Xisco,Mastandrea, Marco M.,Pericàs, Miquel A.
, p. 6402 - 6408 (2020/07/13)
A photoredox strategy for the synthesis of a wide range of allylic amines and ethers from carboxylic acids and alkynes has been developed. This approach relies on the perturbation of the ground-state electronic properties of terminal alkynes through the formation and photoexcitation of copper acetylide intermediates. This process takes place through cooperative copper and organic photoredox catalysis and can be carried out in a stereodivergent manner. Thus, a systematic multivariate HTE screening spotlighted that a switch in the stereochemical outcome can be provoked by choosing an appropriate combination of ligand and base. The developed methodology has been applied to the stereoselective coupling of primary, secondary, and tertiary alkyl radicals with (hetero)aromatic terminal alkynes. As an additional practicality, similar reaction conditions allowed for the use of aromatic amines as radical precursors in a cross dehydrogenative coupling for the direct vinylation of inactivated C-H bonds.
NiCl2-catalyzed radical cross decarboxylative coupling between arylpropiolic acids and cyclic ethers
Wan, Zi-juan,Wang, Jin-yuan,Luo, Jun
supporting information, p. 613 - 616 (2019/01/29)
A direct alkenylation of cyclic ethers via radical cross decarboxylative coupling process catalyzed by NiCl2 and using DTBP as radical initiator and oxidant was developed. A variety of arylpropiolic acids and cyclic ethers were transformed into the corresponding 2-arylvinyl cyclic ethers in moderate to excellent yields. Mechanistic experiments were conducted to determine the nature of the reaction intermediates, and a plausible reaction mechanism involving NiCl2-promoted radical process was proposed.
Nickel(II) Tetraphenylporphyrin as an Efficient Photocatalyst Featuring Visible Light Promoted Dual Redox Activities
Mandal, Tanumoy,Das, Sanju,De Sarkar, Suman
supporting information, p. 3200 - 3209 (2019/05/16)
Nickel(II) tetraphenylporphyrin (NiTPP) is presented as a robust, cost-effective and efficient visible light induced photoredox catalyst. The ground state electrochemical data (CV) and electronic absorption (UV-Vis) spectra reveal the excited state redox potentials for [NiTPP]*/[NiTPP].? and NiTPP].+/[NiTPP]* couples as +1.17 V and ?1.57 V vs SCE respectively. The potential values represent NiTPP as a more potent photocatalyst compare to the well-explored [Ru(bpy)3]2+. The non-precious photocatalyst exhibits excited state redox reactions in dual fashions, i. e., it is capable of undergoing both oxidative as well as reductive quenching pathways. Such versatility of a photocatalyst based on first-row transition metals is very scarce. This unique phenomenon allows one to perform diverse types of redox reactions by employing a single catalyst. Two different sets of chemical reactions have been performed to represent the synthetic utility. The catalyst showed superior efficiency in both carbon-carbon and carbon-heteroatom bond-forming reactions. Thus, we believe that NiTPP is a valuable addition to the photocatalyst library and this study will lead to more practical synthetic applications of earth-abundant-metal-based photoredox catalysts. (Figure presented.).
Visible Light Mediated C(sp3)-H Alkenylation of Cyclic Ethers Enabled by Aryl Ketone
Zhang, Mengmeng,Yang, Liming,Yang, Hui,An, Guanghui,Li, Guangming
, p. 1606 - 1609 (2019/03/27)
C?H alkenylation of cyclic ethers (THF, 1,4-dioxane) using the readily available nitroalkenes as the alkenylating reagents has been developed. It allows the rapid access to the α-alkenyl ethers with high E-selectivity. The previous inaccessible α-dienyl e
Method for synthesizing cis-olefin by catalyzing decarboxylation coupling reaction of NHP ester and aryl-terminated alkyne with iridium
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Paragraph 0081-0082; 0099; 0101, (2019/02/13)
The invention provides a method for synthesizing Z-selective olefin by catalyzing a decarboxylation coupling reaction of an NHP ester and aryl-terminated alkyne with iridium. The aryl-terminated alkyne and its derivative and the NHP ester undergo a one-po
