BPh<sub>3</sub>-Catalyzed [2+3] Cycloaddition of Ph<sub>3</sub>PCCO with Aldonitrones: Access to 5-Isoxazolidinones with Exocyclic Phosphonium Ylide Moieties
作者:Amandeep Brar、Daniel K. Unruh、Natalie Ling、Clemens Krempner
DOI:10.1021/acs.orglett.9b02192
日期:2019.8.16
exocyclic phosphonium ylide functionalities via [2+3] cycloaddition of Ph3PCCO and aldonitrones has been developed and applied in the synthesis of 4-alkylidene-5-isoxazolidinones viaWittig olefination. The reaction proceeds by BPh3 catalysis under mild conditions and with a broad substrate scope. A reaction pathway involving the activation of the aldonitrone via interactions with the Lewis acid BPh3 is
In the presence of TMSCl, the [3 + 2] cycloaddition of oxazol-5-(4H)-ones with nitrones proceeded smoothly and furnished the desired isoxazolidin-5-ones with high diastereoselectivities in reasonable chemical yields. The chemical structure of the title compounds was firmly confirmed by X-ray single-crystal structure analysis.
synthetically useful propargyl hydroxylamines. It is noted that neither the Lewis acids (InCl3, In(OTf)3) nor the metal amides (In(HMDS)3) have activity; only the hybrids worked well, and the catalytic activity of the hybrids was shown to be much higher than that of previously reported catalysts for this reaction. The concept of a Lewis acid/metal amide hybrid as a catalyst may be expanded to broad acid/base
Nafion supported molybdenum oxychloride: Recyclable catalyst for one-pot synthesis of nitrones via direct condensation/oxidation of primary amines and aldehydes using UHP as oxidant
作者:Bhawan Singh、Suman L. Jain、Praveen K. Khatri、Bir Sain
DOI:10.1039/b914402a
日期:——
Immobilization of molybdenum(VI) oxychloride to the surface of perfluorinated ion-exchange polymer “Nafion”via an ion exchange method was carried out for the first time. The prepared Nafion immobilized molybdenum(VI) oxychloride catalyst was used for the direct synthesis of nitrones via one-pot condensation/oxidation of primary amines with aldehydesusing solid urea-hydrogen peroxide (UHP) as oxidant
Accessing benzooxadiazepines<i>via</i>formal [4 + 3] cycloadditions of aza-<i>o</i>-quinone methides with nitrones
作者:Yong-Sheng Zheng、Liang Tu、Li-Mei Gao、Rong Huang、Tao Feng、Huan Sun、Wen-Xuan Wang、Zheng-Hui Li、Ji-Kai Liu
DOI:10.1039/c8ob00201k
日期:——
An unprecedented and efficient [4 + 3] cycloaddition of N-(ortho-chloromethyl)aryl amides with nitrones has been developed. This approach provides easy access to a series of seven-membered benzooxadiazepine derivatives in good to excellent yields (up to 99% yield) under mild reaction conditions.