226931-47-1Relevant articles and documents
Cu-Catalyzed Synthesis of Benzoxazole with Phenol and Cyclic Oxime
Wang, Zheng-Hai,Wang, Dong-Hui
supporting information, p. 782 - 785 (2022/01/20)
A Cu-catalyzed straightforward synthesis of benzoxazoles from free phenols and cyclic oxime esters is reported. The mild reaction conditions tolerate various electron-withdrawing and electron-donating functional groups on both substrates, affording benzoxazoles in moderate to good yields. With this protocol, large-scale syntheses of Ezutromid and Flunoxaprofe in one or two steps are demonstrated. A catalytic mechanism, which includes Cu-catalyzed amination via inner-sphere electron transfer and consequent annulation, is proposed.
Access to pyridines via cascade nucleophilic addition reaction of 1,2,3-triazines with activated ketones or acetonitriles
Zhang, Yuan,Luo, Han,Lu, Qixing,An, Qiaoyu,Li, You,Li, Shanshan,Tang, Zongyuan,Li, Baosheng
supporting information, p. 393 - 396 (2020/05/18)
We studied the cascade nucleophilic addition reactions of 1,2,3-triazines with activated acetonitriles or ketones, which were used to construct highly substituted pyridines that are not easily accessed by conventional methods. The strategy addressed some structural diversity issues currently facing medicinal chemistry, and the resulting pyridines could be used as convenient precursors for the synthesis of related pharmaceuticals. In particular, our method was applied to the syntheses of the marketed drug etoricoxib and several biologically important molecules in a few steps.
Enantioselective decarboxylative Mannich reaction of β-keto acids withC-alkynylN-BocN,O-acetals: access to chiral β-keto propargylamines
Chen, Li-Jun,Li, Wei,Shen, Bao-Chun,Sun, Zhong-Wen,Xie, Hui-Ding,Zhang, Cong-Cong
supporting information, p. 8607 - 8612 (2021/10/20)
The chiral keto-substituted propargylamines are an essential class of multifunctional compounds in the field of organic and pharmaceutical synthesis and have attracted considerable attention, but the related synthetic approaches remain limited. Therefore, a concise and efficient method for the enantioselective synthesis of β-keto propargylaminesviachiral phosphoric acid-catalyzed asymmetric Mannich reaction between β-keto acids andC-alkynylN-BocN,O-acetals as easily availableC-alkynyl imine precursors has been demonstrated here, affording a broad scope of β-ketoN-Boc-propargylamines in high yields (up to 97%) with generally high enantioselectivities (up to 97?:?3 er).
Chiral Vanadyl(V) Complexes Enable Efficient Asymmetric Reduction of β-Ketoamides: Application toward (S)-Duloxetine
Chen, Chien-Tien,Maity, Nabin Ch.,Agarwal, Rachit,Lai, Chien-Fu,Liao, Yiya,Yu, Wei-Ru
supporting information, p. 6408 - 6419 (2020/07/14)
High-valent chiral oxidovanadium(V) complexes derived from 3,5-substituted-N-salicylidene-l-tert-leucine were used as catalysts in asymmetric reduction of N-benzyl-β-ketoamides. Among six different solvents, three different alcohol additives, and two different boranes examined, the use of pinacolborane in tetrahydrofuran (THF) with a t-BuOH additive led to the best results at -20 °C. The corresponding β-hydroxyamides can be furnished with yields up to 92percent and an enantiomeric excess (ee) up to 99percent. We have successfully extended this catalytic protocol for the synthesis of an (S)-duloxetine precursor.
Nickel-catalyzed enantioselective hydrogenation of β-(acylamino)acrylates: Synthesis of chiral β-amino acid derivatives
Li, Xiuxiu,You, Cai,Li, Shuailong,Lv, Hui,Zhang, Xumu
supporting information, p. 5130 - 5133 (2017/11/06)
The nickel-catalyzed asymmetric hydrogenation of β-(acylamino)acrylates has been developed, affording chiral β-amino acid derivatives with excellent yields (95-99% yield) and enantioselectivities (97-99% ee). With the Ni-Binapine system, high enantioselectivities (98-99% ee) have also been obtained in the hydrogenation of Z/E isomeric mixtures of β-alkyl and β-aryl β-(acylamino)acrylates. The synthesis of chiral β-amino acid derivatives on a gram scale has also been achieved with 0.2 mol % catalyst loading.
Base initiated aromatization/CO bond formation: A new entry to O-pyrazole polyfluoroarylated ethers
Tang, Xiangyang,Chang, Jing,Liu, Cuibo,Zhang, Bin
supporting information, p. 6534 - 6537 (2015/01/08)
A base initiated intermolecular SNAr reaction of pyrazolones with polyfluoroarenes was developed. The process involved the isomerization aromatization of pyrazolone followed by the CO bond formation via the selective CF bond cleavage. With this strategy, a wide range of O-pyrazole polyfluoroarylated ethers bearing diverse functional groups were synthesized in mild to good yields. Additionally, our method was also applied to the isoxazol substrates.
Nickel-catalyzed asymmetric transfer hydrogenation of olefins for the synthesis of α- And β-amino acids
Yang, Peng,Xu, Haiyan,Zhou, Jianrong
supporting information, p. 12210 - 12213 (2016/02/18)
The field of asymmetric (transfer) hydrogenation of prochiral olefins has been dominated by noble metal catalysts based on rhodium, ruthenium, and iridium. Herein we report that a simple nickel catalyst is highly active in the transfer hydrogenation using
HOTf mediated cascade reactions of 1-arenoylcyclopropanecarboxylic acids with arenes
Chen, Gen-Qiang,Tang, Xiang-Ying,Shi, Min
supporting information; scheme or table, p. 2340 - 2342 (2012/04/18)
The cascade reactions of 1-arenoylcyclopropanecarboxylic acids with arenes proceed smoothly in freshly distilled HOTf to give the corresponding tetrahydro-5H-benzo[c]fluorene derivatives in good yields along with high stereoselectivities under mild conditions. The Royal Society of Chemistry.
Gold/copper-catalyzed activation of the aci-form of nitromethane in the synthesis of methylene-bridged bis-1,3-dicarbonyl compounds
Balamurugan, Rengarajan,Manojveer, Seetharaman
supporting information; experimental part, p. 11143 - 11145 (2011/11/05)
Activation of the aci-form of nitromethane using Lewis acids for the attack of carbon nucleophiles was studied. 1,3-Dicarbonyl compounds in the presence of catalytic amounts of AuCl3 or Cu(OTf)2 in nitromethane solvent could be converted into methylene-bridged bis-1,3-dicarbonyl compounds.
Triclorosilane-mediated stereoselective synthesis of β-amino esters and their conversion to highly enantiomerically enriched β-lactams
Guizzetti, Stefania,Benaglia, Maurizio,Bonsignore, Martina,Raimondi, Laura
supporting information; experimental part, p. 739 - 743 (2011/04/22)
A highly stereoselective trichlorosilane-mediated reduction of N-benzyl enamines was developed; the combination of a low cost, easy to make metal-free catalyst and an inexpensive chiral auxiliary allowed to perform the reaction on substrates with different structural features often with total control of the stereoselectivity. By easy deprotection through hydrogenolysis followed by conversion of β-aminoester to 2-azetidinones, the synthesis of enantiomerically pure β-lactams (>98% e.e.) was successfully accomplished.
