3468-53-9Relevant academic research and scientific papers
Cobalt-Catalyzed Selective Dearomatization of Pyridines to N-H 1,4-Dihydropyridines
Pang, Maofu,Shi, Le-Le,Xie, Yufang,Geng, Tianyi,Liu, Lan,Liao, Rong-Zhen,Tung, Chen-Ho,Wang, Wenguang
, p. 5013 - 5021 (2022/04/28)
Catalytic reduction of pyridines to N-H 1,4-dihydropyridines is exceptionally challenging because they are essential intermediates to form tetrahydropyridines. Using a facile dihydrogen source H3N·BH3to activate the pyridine ring in situ, we have achieved selective transfer hydrogenation of nicotinate derivatives to N-H 1,4-dihydropyridines by cobalt-amido cooperative catalysis. The reactions operate smoothly under mild conditions to produce a variety of N-H 1,4-dihydropyridines with high chemo- and regioselectivity. This catalytic method also provides a practical protocol to regenerate Hantzsch analogues after delivery of H2
Mechanically induced solvent-free esterification method at room temperature
Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
, p. 5080 - 5085 (2021/02/05)
Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
Palladium-catalyzed aryloxy- and alkoxycarbonylation of aromatic iodides in γ-valerolactone as bio-based solvent
Tukacs, József M.,Marton, Bálint,Albert, Eszter,Tóth, Imre,Mika, László T.
, (2020/08/11)
Fossil-based solvents and triethylamine as a toxic and volatile base were successfully replaced with γ-valerolactone as a non-volatile solvent and K2CO3 as inorganic base in the alkoxy- and aryloxycarbonylation of aryl iodides using phosphine-free Pd catalyst systems. By this, the traditional systems were not simply replaced but also significantly improved. In the study, the effects of different reaction parameters, i.e. the use of several other solvents, the temperature, the carbon monoxide pressure, the base and the catalyst concentrations, were evaluated in details on the efficiency of the carbonylations. To gather some information on the mechanism of these reactions, the effects of the electronic parameters (σ) of various aromatic substituents of the aryl iodides as well as the influence of para-substitution of phenol were investigated on the activity. For a comparison, the aryl-substituted aryl iodides were also reacted with methanol and aryl iodide was also alkoxycarbonylated using several different lower alcohols. From the observed correlations between the electronic parameters of the aromatic substituents and the rates, it appears that the rate determining step is the oxidative addition of Ar–I to Pd0, provided that sufficient amounts of nucleophiles are present for the ester formation. If this is not the case, the rate of nucleophile attack might determine the overall rate.
Synthesis of phenyl esters using SiO2-SO3H catalyst in conventional heating and microwave-irradiated esterification processes
Barbosa, Sandro L.,Ottone, Myrlene,De Freitas, Milton,Lima, Camila D.,Nelson, David L.,Clososki, Giuliano C.,Caires, Franco J.,Klein, Stanlei I.,Hurtado, Gabriela R.
, p. 3663 - 3668 (2019/05/08)
A SiO2-SO3H amorphous catalyst containing a small surface area of 115.0 m2g-1 and 1.32 mmol H+/g was prepared from fine construction sand and sodium carbonate and sulfonated with H2SO4. In a 10% (w/w) basis, it is very efficient for catalyzing the esterification of carboxylic acids with phenol. The reaction processes were performed using conventional heating and under microwave irradiation. The yields were higher in the microwave-irradiated esterification. The catalyst could be used for three esterification sequences in both processes.
Orientation-dependent conformational polymorphs in two similar pyridine/pyrazine phenolic esters
Samie, Ali,Salimi, Alireza
, p. 3721 - 3730 (2019/06/21)
On the basis of crystal engineering, two similar esters of phenyl pyridine-2-carboxylate (I) and phenyl pyrazine-2-carboxylate (II) were designed and synthesized. The compounds were characterized using FT-IR, mass spectrometry, CHN-elemental analyses, NMR and PXRD. For each compound, two polymorphs were obtained (Ia, Ib and IIa, IIb) and identified by TGA, DSC and SCXRD. A comparison of the crystal structures of the polymorphs revealed that the different torsion angles of the pyrazine (τ1) and phenyl (τ2) rings to the ester backbone resulted in the conformers I and II, respectively. Theoretical criteria (max(Δθ), rmsd[r]-crystal, energy profile) confirmed that the structural differences in the conformers are in the range of acceptable values for the detection of conformational changes. The phase stability of the polymorphs was investigated by slurry and grinding methods as well as by the HSM technique. Since the orientations of pyrazine and phenyl moieties were altered in the polymorphs, the hydrogen bond donor and acceptors exhibited meaningful supramolecular architectures in the crystal packing as well as C-H?N, C-H?O and C-H?π interactions. The energetic study of the noncovalent interactions in the molecular pairs (dimers) of the polymorph crystal structures was performed by DFT-D calculations.
Method of coupling, and the coupling method using the aromatic group-substituted heterocyclic compound
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Paragraph 0202-0204, (2020/09/17)
Provided is an easy method (coupling method) capable of easily synthesizing a compound group in which aromatic molecules and aromatic molecules are coupled, a compound group in which aromatic molecules and alkene molecules are coupled, and the like without producing halogen waste and without the need to use scarce and expensive palladium. A compound (A) shown by general formula (A): Ar-H and a compound (B1) shown by general formula (B1): RaOCO-Ar', a compound (B2) shown by general formula (B2): RbCH=C(Ar")2, or a compound (B3) shown by general formula (B3): RcOCOCH=C(Ar")2 are reacted in the presence of a nickel compound.
N-(3,5-dimethyladamantane-1-yl)-N'-substituted phenylurea compound as well as preparation method and application thereof
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Paragraph 0072; 0073; 0116; 0117, (2017/12/28)
The invention belongs to the technical field of medicinal chemistry, in particular to N-(3,5-dimethyladamantane-1-yl)-N'-substituted phenylurea compounds as well as preparation methods and application thereof. The compounds have the structure shown in the formula I. The compounds are proved that the compounds can improve the image recognition memory, the working and learning memory, the spatial learning and memory ability of model rats and has good anti-alzheimer effects by the new object discrimination experiments, Y-maze experiments, positioning navigation and space exploration experiments in mats. The formula I is shown in the description.
Metal-Free O-Arylation of Carboxylic Acid by Active Diaryliodonium(III) Intermediates Generated in situ from Iodosoarenes
Dohi, Toshifumi,Koseki, Daichi,Sumida, Kohei,Okada, Kana,Mizuno, Serina,Kato, Asami,Morimoto, Koji,Kita, Yasuyuki
supporting information, p. 3503 - 3508 (2017/09/13)
The metal-free arylative coupling of carboxylic acids using iodosoarenes without the use of a catalyst and base, which is applicable to even a highly-polar molecule bearing multiple alcohol groups, is reported. The in situ preparation of the reactive diaryliodonium(III) carboxylates is the important key to this approach, and the introduction of the trimethoxybenzene auxiliary enables both the smooth salt formations and the selective aryl transfer events during the couplings. (Figure presented.).
Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2
Carle, Myriam S.,Shimokura, Grace K.,Murphy, Graham K.
supporting information, p. 3930 - 3933 (2016/08/24)
A novel, in-situ synthesis of dichlorotriphenylphosphorane (Ph3PCl2) is accomplished upon combining PPh3and the easily prepared hypervalent iodine reagent iodobenzene dichloride (PhICl2). The phosphorane is selectively generated in the presence of carboxylic acid or alcohol residues to rapidly produce acyl chlorides and alkyl chlorides in high yields. Addition of EtOH, PhOH, BnOH, Et2NH or CH2N2results in the direct synthesis of esters, amides and diazo ketones from carboxylic acids.
One for Many: A Universal Reagent for Acylation Processes
Moon, Hyun Kyung,Sung, Gi Hyeon,Kim, Bo Ram,Park, Jong Keun,Yoon, Yong-Jin,Yoon, Hyo Jae
supporting information, p. 1725 - 1730 (2016/06/09)
This work describes acylation reactions facilitated by a type of heterocycle-based acyl transfer agent, 2-acyloxypyridazinone. Reactions of 2-acyloxypyridazinone with carboxylic acids yield mixed carbonic anhydride intermediates, which are reactive and could be coupled with a wide range of substrates including acids, amines, alcohols, and thiols. The wide substrate scope, ease of operation (no additive or catalyst), storage and handling stability, and atom-efficiency from recycling the heterocycle carrier make the reported acylating agent attractive for acylation-based coupling reactions.
