955-83-9Relevant academic research and scientific papers
Hexafluoroisopropanol as solvent and promotor in the Paal-Knorr synthesis of N-substituted diaryl pyrroles
Schirmacher, Robert H.E.,R?sch, Daniel,Thomas, Franziska
, (2021/02/20)
An additive-free synthesis of challenging N-substituted aryl pyrroles from the often poorly soluble corresponding 1,4-diketones by means of the Paal-Knorr pyrrole synthesis is reported, which makes use of the unique properties of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent and reaction promotor. Our procedure offers simple execution and purification as well as easy scale-up and can be applied in the Paal-Knorr synthesis of a large number of structurally diverse pyrroles including the synthetically challenging tetra- and penta-substituted pyrroles in moderate to excellent yields. HFIP can also be used as solvent in the Paal-Knorr synthesis of furans and thiophenes; however, the solvent effect is more pronounced in synthesis of pyrroles.
Aerobic Oxidative Dehydrogenation of Ketones to 1,4-Enediones
Zhao, Bao-Yin,Zhang, Xing-Long,Guo, Rui-Li,Wang, Meng-Yue,Gao, Ya-Ru,Wang, Yong-Qiang
supporting information, p. 1216 - 1221 (2021/02/20)
An efficient and unprecedented strategy for the synthesis of 1,4-enediones from saturated ketones has been developed via palladium-catalyzed oxidative dehydrogenation. The protocol employs molecular oxygen as the sole oxidant and represents an atom- and step-economic process. The approach showed broad substrate scope, good functional group tolerance, and complete E-stereoselectivity. The reaction mechanism has been investigated through deuterium-labeling experiments and intermediate experiments.
Method for preparing furan compound from brominated arone
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Page/Page column 5, (2021/06/13)
The invention provides a method for synthesizing a furan compound by taking brominated arone and methyl ketone or cyclic ketone as raw materials and directly reacting under the action of tetraisopropyl titanate. The method comprises the following steps: under the protection of inert gas, stirring and heating a reaction mixture of methyl ketone or cyclic ketone and bromo-arone, and then adding tetraisopropyl titanate for reaction; and after the reaction is finished, separating and purifying the obtained reaction mixture to obtain the polysubstituted furan compound. The synthesis method provided by the invention has the advantages of easily available raw materials, low cost, simple operation and easy control, no solvent, good substrate universality and functional group compatibility, and is suitable for industrial mass production.
Reaction of Lithiated Propargyl Ethers with Carbonyl Compounds-A Regioselective Route to Furan Derivatives
Linder, Igor,Klemme, Robby,Reissig, Hans-Ulrich
, p. 765 - 774 (2020/11/13)
The deprotonation of 3-Aryl-substituted alkyl propargyl ethers with n-butyllithium provides an ambident anion that reacts with carbonyl compounds to provide mixtures of γ-substituted products with alkoxyallene substructure and of α-substituted propargyl ethers. The ratio of the two product types strongly depends on the solvent: in diethyl ether the γ-substituted products predominate whereas the more polar tetrahydrofuran favors the α-Adducts. The primary addition products undergo 5-endo-trig or 5-endo-dig cyclizations under various reaction conditions to afford isomeric furan derivatives. The highest selectivity in favor of α-substituted products was achieved by employing a MOM-protected propargyl ether. During the protonation step no evidence for a proton shift leading to an isomeric allenyl anion was found. A brief mechanistic discussion tries to rationalize the observed regio? selectivities.
Bifunctional phosphine ligand-enabled gold-catalyzed direct cycloisomerization of alkynyl ketones to 2,5-disubstituted furans
Hu, Xiaojun,Zhou, Bingwei,Jin, Hongwei,Liu, Yunkui,Zhang, Liming
, p. 7297 - 7300 (2020/07/14)
An efficient synthesis of 2,5-disubstituted furans directly from alkynyl ketones has been developed via tandem gold(i)-catalyzed isomerization of alkynyl ketones to allenyl ketones and cycloisomerization. The key to the success of this chemistry is the use of a biphenyl-2-ylphosphine ligand featuring a critical remote tertiary amino group.
Synthesis of 1,4-Dicarbonyl Compounds by Visible-Light-Mediated Cross-Coupling Reactions of α-Chlorocarbonyls and Enol Acetates
Liu, Qiang,Wang, Rui-Guo,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
supporting information, p. 4391 - 4396 (2020/09/21)
Herein, we report a protocol for visible-light-mediated radical coupling reactions of α-chloroketones and enol acetates to afford 1,4-dicarbonyl compounds, which are important precursors and intermediates in organic synthesis. The reaction involves photoredox-catalyzed activation of the α-chloroketone upon photoelectron transfer, carbon–chlorine bond cleavage, and coupling of the resulting radical with the carbon–carbon double bond of the enol acetate. This mild protocol has a wide substrate scope and moderate to good yields. (Figure presented.).
Synergistic Activation of Amides and Hydrocarbons for Direct C(sp3)–H Acylation Enabled by Metallaphotoredox Catalysis
Baik, Mu-Hyun,Choi, Seulhui,Hong, Soon Hyeok,Lee, Geun Seok,Won, Joonghee
supporting information, p. 16933 - 16942 (2020/08/03)
The utilizations of omnipresent, thermodynamically stable amides and aliphatic C(sp3)?H bonds for various functionalizations are ongoing challenges in catalysis. In particular, the direct coupling between the two functional groups has not been realized. Here, we report the synergistic activation of the two challenging bonds, the amide C?N and unactivated aliphatic C(sp3)?H, via metallaphotoredox catalysis to directly acylate aliphatic C?H bonds utilizing amides as stable and readily accessible acyl surrogates. N-acylsuccinimides served as efficient acyl reagents for the streamlined synthesis of synthetically useful ketones from simple C(sp3)?H substrates. Detailed mechanistic investigations using both computational and experimental mechanistic studies were performed to construct a detailed and complete catalytic cycle. The origin of the superior reactivity of the N-acylsuccinimides over other more reactive acyl sources such as acyl chlorides was found to be an uncommon reaction pathway which commences with C?H activation prior to oxidative addition of the acyl substrate.
A Convoluted Polyvinylpyridine-Palladium Catalyst for Suzuki-Miyaura Coupling and C?H Arylation
Ohno, Aya,Sato, Takuma,Mase, Toshiaki,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
supporting information, p. 4687 - 4698 (2020/09/07)
The development of highly active and reusable supported catalysts for Suzuki-Miyaura coupling and catalytic C?H arylation is important for fundamental and applied chemistry, with these reactions being used to produce medical compounds and functional materials. Herein, we found that a mesoporous composite made of a linear poly(4-vinylpyridine) and tetrachloropalladate acted as a dual-mode catalyst for a variety of cross-coupling reactions, with both Pd nanoparticles and a Pd complex catalyst being observed under different conditions. The polyvinylpyridine-palladium composite 1 was readily prepared via the molecular convolution of poly(4-vinylpyridine) and sodium tetrachloropalladate to provide a hardly soluble polymer-metal composite. The Suzuki-Miyaura coupling and the C?H arylation of aryl chlorides and bromides with arylboronic acids, thiophenes, furans, benzene, and anisole proceeded in the presence of 0.004 mol% (40 mol ppm) to 1 mol% Pd of 1 to afford the corresponding coupling products in high yields. Furthermore, the catalyst was reused without an appreciable loss of activity. Pharmaceutical compounds and functional materials were synthesized via the coupling reactions. N2 gas adsorption/desorption analysis indicated that the catalyst had a mesoporous nature, which played a crucial role in the catalysis. In the Suzuki-Miyaura couplings, in situ generated palladium nanoparticles in the polymer matrix were catalytically active, while a polymeric Pd(II) complex was crucial in the C?H arylations. These catalytic species were investigated via XAFS, XPS, far-infrared absorption, and Raman spectroscopies, as well as DFT calculations. (Figure presented.).
Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides: Via C-C bond activation
Wen, Si,Lv, Weiwei,Ba, Dan,Liu, Jing,Cheng, Guolin
, p. 9104 - 9108 (2019/10/21)
The first successful example of deacylative annulation of 1,3-diones with sulfoxonium ylides was achieved through Ru(ii)-catalyzed C-C bond activation. The excellent chemoselectivity and broad substrate scope render this method a practical and versatile approach for the preparation of (hetero)aryl and alkenyl substituted furans, which are valuable units in many biologically active compounds and functional materials. A preliminary mechanistic study reveals that this process involves a deacylative α-ruthenation to generate key alkyl Ru(ii) intermediates with the release of a benzoic acid fragment.
Copper Nanoparticles on Ordered Mesoporous Carbon Nitride Support: a Superior Catalyst for Homo- and Cross-Coupling of Terminal Alkynes under Base-Free Conditions
Xu, Hang,Wu, Liangying,Tian, Jing,Wang, Jun,Wang, Peng,Niu, Xiyu,Yao, Xiaoquan
, p. 6690 - 6696 (2019/11/02)
A novel ordered mesoporous carbon nitride (OMCN) was synthesized as a functionalized support with 2,4,6-trichloro-1,3,5-triazine and benzidine as starting materials in the presence of SBA-15 as a template. Copper nanoparticles were then loaded on the C–N material to achieve a novel nanocomposite catalyst (Cu NPs-OMCN). The nanocomposite was utilized as a highly efficient catalyst for homo- and cross-coupling of terminal alkynes under base-free conditions in ethanol, and various symmetrical and unsymmetrical 1,3-diynes were obtained with good to excellent yields. Moreover, based on this reaction, a one-pot approach to synthesize 2,5-disubstituted thiophenes and furans from terminal alkynes were developed. Furthermore, the heterogeneous catalyst could be recovered and reused conveniently for several times with satisfactory yields.
