495-18-1Relevant articles and documents
Boronic Acid-Catalyzed, Highly Enantioselective Aza-Michael Additions of Hydroxamic Acid to Quinone Imine Ketals
Hashimoto, Takuya,Gálvez, Alberto Osuna,Maruoka, Keiji
, p. 16016 - 16019 (2015)
Boronic acid is one of the most versatile organic molecules in chemistry. Its uses include organic reactions, molecular recognition, assembly, and even medicine. While boronic acid catalysis, which utilizes an inherent catalytic property, has become an important research objective, it still lags far behind other boronic acid chemistries. Here, we report our discovery of a new boronic acid catalysis that enables the aza-Michael addition of hydroxamic acid to quinone imine ketals. By using 3-borono-BINOL as a chiral boronic acid catalyst, this reaction could be implemented in a highly enantioselective manner, paving the way to densely functionalized cyclohexanes.
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Goldenberg,Spoerri
, p. 1327,1328 (1958)
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Synthesis, structure and magnetic properties of phenylhydroxamate-based coordination clusters
Tirfoin, Rmi,Chamoreau, Lise-Marie,Li, Yanling,Fleury, Benoit,Lisnard, Laurent,Journaux, Yves
, p. 16805 - 16817 (2014)
The strategic recombination of preformed coordination clusters in the presence of polymodal bridging ligands has successfully led to the characterisation of five new compounds of structural and magnetic interest. Indeed using the dinuclear complex [M2(H2O)(piv)4(Hpiv)4] (M = Co, Ni; Hpiv = pivalic acid) as starting material and reacting it with phenylhydroxamic acid (H2pha) has yielded the four tetrametallic coordination clusters [Co4(Hpha)2(piv)6(Hpiv)4] (1), [Ni4(Hpha)2(piv)6(Hpiv)2(DMF)2] (2), [Co4(Hpha)2(piv)6(EtOH)2(H2O)2] (3), [Ni4(Hpha)2(piv)6(EtOH)2(H2O)2] (4) and the hexanuclear complex [Co6(Hpha)4(piv)8(EtOH)2]·EtOH (5). All the compounds have been structurally characterised revealing a particular binding mode for the hydroxamate ligand. The study of their magnetic properties has been performed and the modelling of these properties has been done using the appropriate hamiltonians for each compound. The experimental data and their modelling show non-zero spin ground states for compounds 4 and 5.
Fast and Cysteine-Specific Modification of Peptides, Proteins and Bacteriophage Using Chlorooximes
Chen, Fa-Jie,Zheng, Mengmeng,Nobile, Vincent,Gao, Jianmin
, (2022/03/15)
This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k2=306±4 M?1s?1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries.
Palladium-Catalyzed 5-exo-dig Cyclization Cascade, Sequential Amination/Etherification for Stereoselective Construction of 3-Methyleneindolinones
Zuo, Youpeng,He, Xinwei,Tang, Qiang,Hu, Wangcheng,Zhou, Tongtong,Hu, Wenbo,Shang, Yongjia
, p. 2117 - 2123 (2020/12/22)
An cascade intramolecular 5-exo-dig cyclization of N-(2-iodophenyl)propiolamides and sequential amination/etherification (with N-hydroxybenzamides, phenyl hydroxycarbamate) protocol for the synthesis of amino- and phenoxy-substituted 3-methyleneindolinones using unexpensive Pd(PPh3)4 as catalyst has been developed. The protocol enables the assembly of structurally important oxindole cores featuring moderate functional group tolerance (particularly the halo group), affording a broad spectrum of products with diverse substituents in good to excellent yields. (Figure presented.).
Thioether-Directed NiH-Catalyzed Remote γ-C(sp3)-H Hydroamidation of Alkenes by 1,4,2-Dioxazol-5-ones
Chen, Qishu,Du, Bingnan,Ouyang, Yuxin,Yu, Wing-Yiu
supporting information, p. 14962 - 14968 (2021/09/29)
A NiH-catalyzed thioether-directed cyclometalation strategy is developed to enable remote methylene C-H bond amidation of unactivated alkenes. Due to the preference for five-membered nickelacycle formation, the chain-walking isomerization initiated by the NiH insertion to an alkene can be terminated at the γ-methylene site remote from the alkene moiety. By employing 2,9-dibutyl-1,10-phenanthroline as the ligand and dioxazolones as the reagent, the amidation occurs at the γ-C(sp3)-H bonds to afford the amide products in up to 90% yield (>40 examples) with remarkable regioselectivity (up to 24:1 rr).
