93-16-3Relevant academic research and scientific papers
Facile Synthesis of Chiral Arylamines, Alkylamines and Amides by Enantioselective NiH-Catalyzed Hydroamination
Meng, Lingpu,Yang, Jingjie,Duan, Mei,Wang, You,Zhu, Shaolin
supporting information, p. 23584 - 23589 (2021/09/28)
Regio- and enantioselective hydroarylamination, hydroalkylamination and hydroamidation of styrenes have been developed by NiH catalysis with a simple bioxazoline ligand under mild conditions. A wide range of enantioenriched benzylic arylamines, alkylamines and amides can be easily accessed by nitroarenes, hydroxylamines and dioxazolones, respectively as amination reagents. The chiral induction in these reactions is proposed to proceed through an enantiodifferentiating syn-hydronickellation step.
Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
, (2022/01/08)
Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Br?nsted base.
Design, synthesis and pharmacological evaluation of novel antiinflammatory and analgesic O-benzyloxime compounds derived from natural eugenol
Da Silva, Rodrigo César,Veiga, Fabiano,Vilela, Fabiana Cardoso,Pereira, André Victor,Da Silva Cunha, Thayssa Tavares,Tesch, Roberta,Viegas, Claudio,Dias, Danielle Ferreira,Giusti-Paiva, Alexandre,Veloso, Marcia Paranho,Fraga, Carlos Alberto Manssour
, p. 1157 - 1166 (2019/10/28)
Background: A new series of O-benzyloximes derived from eugenol was synthesized and was evaluated for its antinociceptive and anti-inflammatory properties. Methods: The target compounds were obtained in good global 25-28% yields over 6 steps, which led us to identify compounds (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-(4- (methylthio)benzyloxime (8b), (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- bromobenzyloxime (8d) and (Z)-5,6-dimethoxy-2,2-dimethyl-2,3-dihydro-1H-inden-1-one-O-4- (methylsulfonyl)benzyloxime (8f) as promising bioactive prototypes. Results: These compounds have significant analgesic and anti-inflammatory effects, as evidenced by formalin-induced mice paw edema and carrageenan-induced mice paw edema tests. In the formalin test, compounds 8b and 8f evidenced both anti-inflammatory and direct analgesic activities and in the carrageenan-induced paw edema, with compounds 8c, 8d, and 8f showing the best inhibitory effects, exceeding the standard drugs indomethacin and celecoxib. Conclusion: Molecular docking studies have provided additional evidence that the pharmacological profile of these compounds may be related to inhibition of COX enzymes, with slight preference for COX-1. These results led us to identify the new O-benzyloxime ethers 8b, 8d and 8f as orally bioactive prototypes, with a novel structural pattern capable of being explored in further studies aiming at their optimization and development as drug candidates.
Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
Zhang, Bo,Qi, Zaojuan,Li, Xinxin,Ji, Jianwei,Zhang, Leilei,Wang, Hua,Liu, Xiaoyan,Li, Changzhi
supporting information, p. 5556 - 5564 (2019/10/28)
Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.
Specific Residues Expand the Substrate Scope and Enhance the Regioselectivity of a Plant O-Methyltransferase
Tang, Qingyun,Bornscheuer, Uwe T.,Pavlidis, Ioannis V.
, p. 3227 - 3233 (2019/07/04)
An isoeugenol 4-O-methyltransferase (IeOMT), isolated from the plant Clarkia breweri, can be engineered to a caffeic acid 3-O-methyltransferase (CaOMT) by replacing three consecutive residues. Here we further investigated functions of these residues by constructing the triple mutant T133M/A134N/T135Q as well as single mutants of each residue. Phenolics with different chain lengths and different functional groups were investigated. The variant T133M improves the enzymatic activities against all tested substrates by providing beneficial interactions to residues which directly interact with the substrate. Mutant A134N significantly enhanced the regioselectivity. It is meta-selective or even specific against most of the tested substrates but para-specific towards 3,4-dihydroxybenzoic acid. The triple mutant T133M/A134N/T135Q benefits from these two mutations, which not only expand the substrate scope but also enhance the regioselectivity of IeOMT. On the basis of our work, regiospecific methylated phenolics can be produced in high purity by different IeOMT variants.
Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans
Liu, Changhui,Pan, Bin,Gu, Yanlong
, p. 979 - 986 (2016/07/06)
Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often plagued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4-dihydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.
Synthesis, characterization and in vitro biological evaluation of [Ru(η6-arene)(N,N)Cl]PF6 compounds using the natural products arenes methylisoeugenol and anethole
Delgado, Ricardo A.,Galdámez, Antonio,Villena, Joan,Reveco, Patricio G.,Thomet, Franz A.
, p. 131 - 137 (2015/04/14)
Abstract Five new organometallic Ru(II) compounds (VI-X) with the general formula [Ru(η6-arene)(N,N)Cl]PF6, where arene-N,N correspond to methylisoeugenol-bipyridine (VI); anethole-bipyridine (VII); methylisoeugenol-ethylenediamine (VIII); anethole-ethylenediamine (IX) and methylisoeugenol-1,2-diaminobenzene (X), have been synthesized, fully characterized and biologically evaluated in vitro. The reaction conditions based on the reduction of [Ru(1,5-COD)Cl2]n in situ with methyleugenol and estragole, which are natural ligands, induced an alkene isomerization on the allylic substituent of coordinated arenes. The Ru(II)-arene bond formation and isomerization of the CC bond on the allyl substituent was confirmed using 1H NMR spectroscopy; this result was validated for compound VIII by X-ray diffraction. An XRD analysis revealed the presence of both enantiomers of the complex in the single-crystal. Compounds IX and X exhibited a better cytotoxic activity in vitro than carboplatin, which is a commercial drug, against three human tumor cell lines (MCF-7, PC-3 and HT-29).
Catalytic cyclometallation of allylbenzenes by EtAlCl2 and Mg as new route to synthesis of dibenzyl butane lignans
Parfenova, Lyudmila V.,Berestova, Tatyana V.,Kovyazin, Pavel V.,Yakupov, Aydar R.,Mesheryakova, Ekaterina S.,Khalilov, Leonard M.,Dzhemilev, Usein M.
, p. 292 - 298 (2015/02/19)
The cyclometallation of allylbenzenes (Ar = Ph, 4-MeO-Ph, 3,4-(MeO)2-Ph) with EtAlCl2 (Et2AlCl) and Mg in the presence of Zr and Ti catalysts (Dzhemilev reaction) has been studied. The reaction run with high diastereoselectivity and gives cyclic organoaluminum compounds, which deuterolysis or hydrolysis gave 2R(S), 3R(S)-dibenzyl butanes with yield of 48-69%. The study of catalyst structure effect on the substrate conversion, reaction chemo- and stereoselectivity showed that the best results were obtained in the case of Cp2ZrCl2 among the tested complexes. The enantioselectivity of neomenthylindenyl or neomenthyltetrahydroindenyl zirconium catalysts in the reaction did not exceed 20%ee. The trans-configuration of the substitutes in the metallacycles formed in the reaction has been proved by X-ray analysis of the hydrolysis product - 2R(S), 3R(S)-dimethyl-1,4-bis[(4′- methoxyphenyl)methyl]-butane. The proposed method could be used for the one-pot diastereoselective synthesis of dibenzyl butane lignans from readily available allylbenzenes.
Total synthesis of cyclogalgravin and its dicarboxyl analog using sc(otf)3-mediated highly diastereoselective ring expansion of 1-(arylhydroxymethyl)cyclopropanecarboxylates
Sakuma, Daichi,Ito, Junki,Sakai, Ryo,Taguchi, Ryota,Nishii, Yoshinori
supporting information, p. 610 - 611 (2014/05/20)
The total synthesis of cyclogalgravin and its dicarboxyl analog was achieved by using the SmI2-promoted Reformatsky type reaction and Sc(OTf)3-mediated diastereoselective ring expansion as key steps.
Ruthenium-catalyzed one-pot synthesis of (E)-(2-arylvinyl)boronates through an isomerization/cross-metathesis sequence from allyl-substituted aromatics
Hemelaere, Remy,Caijo, Frederic,Mauduit, Marc,Carreaux, Francois,Carboni, Bertrand
supporting information, p. 3328 - 3333 (2014/06/09)
We described the efficient preparation of (E)-(2-arylvinyl)boronates from allylbenzene derivatives on the basis of an isomerization/cross-metathesis sequence catalyzed by a modified Hoveyda-Grubbs catalyst. The implementation of the experimental procedure was simple and compatible with a large variety of substrates. This methodology provides a new chemical transformation not described to date. Allyl-substituted aromatics can thus be converted into diversely functionalized compounds, such as (E)-stilbene derivatives or (E)-vinyl azides, in only two steps. Copyright
