20000-53-7Relevant articles and documents
Deprotonation of benzoxazole and oxazole using lithium magnesates
Bayh, Omar,Awad, Hacan,Mongin, Florence,Hoarau, Christophe,Bischoff, Laurent,Trecourt, Francois,Queguiner, Guy,Marsais, Francis,Blanco, Fernando,Abarca, Belen,Ballesteros, Rafael
, p. 5190 - 5196 (2005)
The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways: (1) the equilibration between the open and closed structures is faster than the trapping of the open isomers, and the closed isomers are more reactive than the open ones, or (2) the open isomers react with electrophiles in a intramolecular Passerini type reaction. The nonreactivity of the 2-(isocyano)enolate type structure toward anisaldehyde in the absence of lithium bromide makes the intramolecular Passerini type reaction more plausible.
Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
supporting information, p. 10690 - 10699 (2021/04/09)
Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
, p. 15396 - 15405 (2020/12/02)
The iron-catalyzed hydrogen transfer strategy has been applied to the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles and benzimidazoles.
Synthesis and Anticancer Evaluation of Amide Derivatives of 1,3,4-Oxadiazole Linked with Benzoxazole
Ravinaik,Ramachandran,Rao, M. V. Basaveswara
, p. 1003 - 1008 (2019/07/03)
A novel series of amide 1,3,4-oxadiazole linked benzoxazole derivatives 12a–12j are synthesized and their anticancer activity is screened against four human cancer cell lines including A549 (Lung cancer), MCF7 (Breast cancer), A375 (Melanoma cancer), HT-29 (Colon cancer) using Combretastatin-A4 as a control drug. Among the synthesized compounds, 12c and 12g demonstrate potent anticancer activity against HT-29 cancer cell line with IC50 values of 0.018 and 0.093 μM, respectively, which is higher than the standard drug.
Transition-Metal-Free Alkylation/Arylation of Benzoxazole via Tf2O-Activated-Amide
Niu, Zhi-Jie,Li, Lian-Hua,Liu, Xue-Yuan,Liang, Yong-Min
supporting information, p. 5217 - 5222 (2019/11/13)
A transition-metal-free approach to the alkylation/arylation of benzoxazole was developed by employing Tf2O-activated-amide as the alkylating/arylating reagent. The mild reaction conditions, and particularly insensitivity to air and water, further enhance the synthetic potential in pharmaceutical synthesis. (Figure presented.).
Cesium Fluoride and Copper-Catalyzed One-Pot Synthesis of Benzoxazoles via a Site-Selective Amide C?N Bond Cleavage
Luo, Zhongfeng,Wu, Hongxiang,Li, Yue,Chen, Yuwen,Nie, Jingyi,Lu, Siqi,Zhu, Yulin,Zeng, Zhuo
supporting information, p. 4117 - 4125 (2019/08/01)
We report herein a two-step one-pot strategy for the synthesis of benzoxazoles from amides by using cesium fluoride/copper as catalysts. This approach involves the in situ generation of acyl fluorides from the corresponding amides, and the acyl fluorides undergo transamidation and cyclization to give benzoxazoles in good yields. In this work, the amide C?N bonds are activated by CsF to form the acyl fluoride intermediates, which further react with o-bromoanilines to efficiently yield benzoxazoles. Notably, this methodology demonstrates a broad substrate scope, as primary/secondary benzamides are well tolerated, and this process might facilitate the development of one-pot transformations of amides. (Figure presented.).
CoIII-Catalyzed Isonitrile Insertion/Acyl Group Migration Between C?H and N?H bonds of Arylamides
Kalsi, Deepti,Barsu, Nagaraju,Sundararaju, Basker
supporting information, p. 2360 - 2364 (2018/02/22)
A general efficient and site-selective cobalt-catalyzed insertion of isonitrile into C?H and N?H bonds of arylamides through C?H bond activation and alcohol assisted intramolecular trans-amidation is demonstrated. This straightforward approach overcomes the limitation by the presence of strongly chelating groups. Isolation of CoIII-isonitrile complex B has been achieved for the first time to understand the reaction mechanism.
A Polystyrene-Cross-Linking Bisphosphine: Controlled Metal Monochelation and Ligand-Enabled First-Row Transition Metal Catalysis
Iwai, Tomohiro,Harada, Tomoya,Shimada, Hajime,Asano, Kiichi,Sawamura, Masaya
, p. 1681 - 1692 (2017/08/15)
A polystyrene-cross-linking bisphosphine PS-DPPBz was synthesized through radical emulsion copolymerization between 4-t-butylstyrene as a monomer and tetravinylated 1,2-bis(diphenylphosphino)benzene (DPPBz) as a 4-fold cross-linker. The location of the DPPBz bisphosphine moiety at the branching points of the cross-linked network organic polymer allowed controlled bisphosphine monochelation to transition metals under conditions where homogeneous ligands may form bischelated single metal complexes or multinuclear complexes. PS-DPPBz showed high ligand performance in first-row transition metal catalysis, enabling challenging molecular transformations that were not possible through the screening of existing homogeneous ligands. In the Ni-catalyzed amination of aryl chlorides with N-alkyl-substituted primary amines, the substrate scope has been expanded to include 2,6-disubstituted aryl chlorides and N-tertiary-alkyl-substituted primary amines. PS-DPPBz was effective for the Ni-catalyzed C-H/C-O coupling between 1,3-azoles and monocyclic aryl pivalates, which showed poor reactivity in the reported homogeneous catalytic system based on 1,2-bis(dicyclohexylphosphino)ethane (DCYPE). The usefulness of the polymer-cross-linking strategy was also demonstrated in alkene hydroboration reactions catalyzed by Cu or Co.
KMnO4/HOAc system promoted one-pot synthesis of benzoxazoles from o-aminophenols or oxidative cyclization of o-hydroxyarylidene anilines at room temperature
Mirjalili,Bamoniri,Bagheri
, p. 809 - 814 (2016/04/05)
1,3-Benzoxazoles via oxidative cyclization of corresponding o-hydroxyarylidene anilines was synthesized in the presence of KMnO4/HOAc system. This system also was applied for the one-pot synthesis of 1,3-benzoxazoles from o-amino phenols and aldehydes. The both protocols were processed at room temperature under solvent-free conditions with good to excellent yields.
CARBAMATE DERIVATIVES OF LACTAM BASED N-ACYLETHANOLAMINE ACID AMIDASE (NAAA) INHIBITORS
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Paragraph 0673, (2014/09/29)
Described herein are compounds and pharmaceutical compositions which inhibit N-acylethanolamine acid amidase (NAAA). Described herein are methods for synthesizing the compounds set forth herein and methods for formulating these compounds as pharmaceutical compositions which include these compounds. Also described herein are methods of inhibiting NAAA in order to sustain the levels of palmitoylethanolamide (PEA) and other N-acylethanolamines (NAE) that are substrates for NAAA, in conditions characterized by reduced concentrations of NAE. Also, described here are methods of treating and ameliorating pain, inflammation, inflammatory diseases, and other disorders in which modulation of fatty acid ethanolamides is clinically or therapeutically relevant or in which decreased levels of NAE are associated with the disorder.
