6100-74-9Relevant academic research and scientific papers
Room temperature depolymerization of lignin using a protic and metal based ionic liquid system: an efficient method of catalytic conversion and value addition
Mehta, Mohit J.,Kulshrestha, Akshay,Sharma, Shweta,Kumar, Arvind
, p. 1240 - 1247 (2021/02/26)
Lignin is one of the most abundant biopolymer which can be utilized to synthesize various chemicalsviaits depolymerization. However, depolymerization of lignin generally occurs under very harsh conditions. Herein, we report the efficient depolymerization of ligninviadissolution in a mixed ionic liquid system: ethyl ammonium nitrate (EAN) + prolinium tetrachloromanganate(ii) [Pro]2[MnCl4] at 35 °C and under atmospheric pressure conditions. The high dissolution of lignin in ethyl ammonium nitrate provided a large number of H-bonding sites leading to the cracking of lignin and subsequent oxidative conversion by [Pro]2[MnCl4]viathe formation of metal-oxo bonding between Mn and lignin molecules. The extracted yield of vanillin was found to be 18-20% on lignin weight basisviaGC-MS analysis. The depolymerization of lignin was confirmed by SEM, FT-IR and PXRD analysis. Since lignin contains UV-absorbing functional groups, the regenerated biomass after the recovery of the depolymerized products was further utilized to synthesize a UV-shielding material. The constructed films from such a material exhibited a high SPF value of 22 and were found to be very effective by limiting the UV degradation of rhodamine B thus making the lignin valorization process economically viable and environmentally sustainable.
Iron-catalyzed arene C-H hydroxylation
Cheng, Lu,Wang, Huihui,Cai, Hengrui,Zhang, Jie,Gong, Xu,Han, Wei
, p. 77 - 81 (2021/10/05)
The sustainable, undirected, and selective catalytic hydroxylation of arenes remains an ongoing research challenge because of the relative inertness of aryl carbon-hydrogen bonds, the higher reactivity of the phenolic products leading to over-oxidized by-products, and the frequently insufficient regioselectivity. We report that iron coordinated by a bioinspired L-cystine-derived ligand can catalyze undirected arene carbon-hydrogen hydroxylation with hydrogen peroxide as the terminal oxidant. The reaction is distinguished by its broad substrate scope, excellent selectivity, and good yields, and it showcases compatibility with oxidation-sensitive functional groups, such as alcohols, polyphenols, aldehydes, and even a boronic acid. This method is well suited for the synthesis of polyphenols through multiple carbon-hydrogen hydroxylations, as well as the late-stage functionalization of natural products and drug molecules.
Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
, p. 4348 - 4358 (2020/09/22)
Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
Synthesis of aryl-substituted 2-methoxyphenol derivatives from maltol-derived oxidopyrylium cycloadducts through an acid-mediated ring contraction cascade
Bejcek, Lauren P.,Murelli, Ryan P.
supporting information, p. 3203 - 3205 (2020/03/23)
Oxidopyrylium cycloadducts derived from maltol and aryl acetylenes undergo acid-mediated rearrangements to generate aryl-substituted 2-methoxyphenol (guaiacol) derivatives. Specifically, the cycloadducts react with boron trichloride to form 2-methoxy-5-ar
A convenient synthetic approach to dioncoquinone B and related compounds
Khmelevskaya, Ekaterina A.,Pelageev, Dmitry N.
supporting information, p. 1022 - 1024 (2019/03/13)
A total synthesis of dioncoquinone B and related compounds, including ancistroquinones B, C and malvon A, is presented. The strategy is based on available reagents and can be used as a preparative synthesis of a number of natural and synthetic biologically active (3-alkyl)-2,7,8-di(tri)methoxy(hydroxy)-1,4-naphthoquinones.
Synthesis of N-Substituted Condensed Tetrahydropyridine-Based Enaminones via Palladium-Catalyzed Intramolecular C–N Cross-coupling
Dou?ová, Hana,R??i?ková, Zdeňka,?im?nek, Petr
supporting information, p. 670 - 684 (2018/01/22)
A number of β-enaminones with secondary amino group (alkyl, cyclopropyl, and aryl) were prepared from corresponding β-diketones. Two general protocols for their palladium-catalyzed intramolecular C–N cross-coupling were established to give corresponding N-substituted condensed tetrahydropyridines in good yields. The methodology is applicable for a wide variety of structural motifs. The work also extends the applicability of novel, recently established, palladium precatalysts to new substrates.
Rh/DuanPhos-Catalyzed Asymmetric Hydrogenation of β-Acetylamino Vinylsulfides: An Approach to Chiral β-Acetylamino Sulfides
Gao, Wenchao,Lv, Hui,Zhang, Xumu
supporting information, p. 2877 - 2880 (2017/06/07)
Rh/DuanPhos-catalyzed asymmetric hydrogenation of challenging β-acetylamino vinylsulfides has been developed, affording chiral β-acetylamino sulfides with high yields and excellent ee's (up to 99% ee). This novel methodology provides an efficient and concise synthetic route to chiral β-acetylamino sulfides. The potential utility of this protocol in the synthesis of Apremilast has also been disclosed.
PROCESSES FOR THE PREPARATION OF APREMILAST AND INTERMEDIATES THEREOF
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Paragraph 0076, (2017/07/29)
Disclosed are processes for the preparation of Apremilast and intermediates for its preparation.
An intramolecular C-N cross-coupling of β-enaminones: A simple and efficient way to precursors of some alkaloids of Galipea officinalis
Douov, Hana,Hork, Radim,Ruikov, Zdeka,imunek, Petr
supporting information, p. 884 - 892 (2015/08/24)
2-Aroylmethylidene-1,2,3,4-tetrahydroquinolines with the appropriate substituents can be suitable precursors for the synthesis of alkaloids from Galipea officinalis (cuspareine, galipeine, galipinine, angustureine). However, only two, rather low-yielding procedures for their synthesis are described in the literature. We have developed a simple and efficient protocol for an intramolecular, palladium or copper-catalysed amination of both chloro- and bromo-substituted 3-amino-1,5-diphenylpent-2-en-1-ones leading to the above-mentioned tetrahydroquinoline moiety. The methodology is superior to the methods published to date.
Computational and Experimental Studies of Phthaloyl Peroxide-Mediated Hydroxylation of Arenes Yield a More Reactive Derivative, 4,5-Dichlorophthaloyl Peroxide
Camelio, Andrew M.,Liang, Yong,Eliasen, Anders M.,Johnson, Trevor C.,Yuan, Changxia,Schuppe, Alex W.,Houk,Siegel, Dionicio
, p. 8084 - 8095 (2015/09/01)
The oxidation of arenes by the reagent phthaloyl peroxide provides a new method for the synthesis of phenols. A new, more reactive arene oxidizing reagent, 4,5-dichlorophthaloyl peroxide, computationally predicted and experimentally determined to possess enhanced reactivity, has expanded the scope of the reaction while maintaining a high level of tolerance for diverse functional groups. The reaction proceeds through a novel "reverse-rebound" mechanism with diradical intermediates. Mechanistic insight was achieved through isolation and characterization of minor byproducts, determination of linear free energy correlations, and computational analysis of substituent effects of arenes, each of which provided additional support for the reaction proceeding through the diradical pathway.
