Asymmetric “Acetylenic” [3+2] Cycloaddition of Nitrones Catalyzed by Cationic Chiral Pd<sup>II</sup>
Lewis Acid
作者:Kazuya Honda、Koichi Mikami
DOI:10.1002/asia.201801016
日期:2018.10.4
Highly enantioselective [3+2] cycloaddition of ynones and nitrones has been developed. Very bulky ligand, DTBM‐SEGPHOS, was used for an effective asymmetric induction over distal reaction centers on the linear ynone dipolarophile and for prevention of PdII catalyst deactivation by coordination of the nitrones. The reaction has wide scope of substrates in both ynones and nitrones.
Regiochemistry of mercury(II) oxide oxidation of unsymmetrical N,N-disubstituted hydroxylamines
作者:Sk.Asrof Ali、S.M. Azhar Hashmi、Mohammad N. Siddiqui、Mohammed I.M. Wazeer
DOI:10.1016/0040-4020(96)00904-0
日期:1996.11
Mercury(II) oxideoxidation of N,N-disubstituted hydroxylamines with the α and α′ carbon atoms containing one and two hydrogen atoms, respectively, gave aldonitrones in a highly regioselective manner. Removal of the α proton is involved in the rate determining step as shown by primary kinetic isotope effect.
Stereoselective Synthesis of Fluoroalkenoates and Fluorinated Isoxazolidinones: N-Substituents Governing the Dual Reactivity of Nitrones
作者:G. K. Surya Prakash、Zhe Zhang、Fang Wang、Martin Rahm、Chuanfa Ni、Marc Iuliucci、Ralf Haiges、George A. Olah
DOI:10.1002/chem.201303509
日期:2014.1.13
α‐Fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones are of vast interest due to their potential biological applications. We now demonstrate the syntheses of (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones by the reactions between nitrones and α‐fluoro‐α‐bromoacetate. By altering N‐substituents in nitrones, (E)‐α‐fluoroalkenoates and 4‐fluoro‐5‐isoxazolidinones can be achieved, respectively, with
One-Pot Synthesis of Functionalized Nitrones from Nitro Compounds
作者:Valérie Gautheron-Chapoulaud、Shashi U. Pandya、Pascale Cividino、Géraldine Masson、Sandrine Py、Yannick Vallée
DOI:10.1055/s-2001-16042
日期:——
The zinc-mediated reduction of nitroalkanes and nitroarenes in the presence of aldehydes is an efficient method to synthesize a wide range of nitrones. This method is mild enough to accommodate a variety of functional groups. It is particularly useful when the intermediate hydroxylamines are unstable and/or water-soluble. We used it to prepare several aromatic, aliphatic and highly functionalized sugar-derived nitrones.
One-flask transformation of secondary amines to nitrones by oxidation with hydrogen peroxide mediated by triscetylpyridinium tetrakis oxodiperoxotungsto-phosphate (PCWP). Some mechanistic considerations
作者:Francesco P. Ballistreri、Ugo Chiacchio、Antonio Rescifina、Gaetano A. Tomaselli、Rosa M. Toscano
DOI:10.1016/s0040-4020(01)89443-6
日期:——
Acyclic and cyclic secondary amines are oxidized to nitrones by H2O2/PCWP system in water/chloroform under phase transfer catalysis conditions. The different acidities of the protons of the carbon atoms α to the nitrogen might be responsible for the identity and ot the stereochemistry of the formed nitrone. The presence of an aromatic ring such as benzene directly linked to the nitrogen represents
在相转移催化条件下,H 2 O 2 / PCWP体系在水/氯仿中将无环和环状仲胺氧化为硝酮。碳原子α的质子对氮的不同酸度可能是所形成的硝酮的身份和立体化学的原因。直接连接到氮上的芳环如苯的存在是一个限制,因为在这种情况下观察到许多氧化产物。就机械方面而言,建议氧化过程可通过胺对过氧金属配合物的过氧化氧的亲核攻击或从胺到氧化剂的单电子转移而开始。