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
AbstractAn eco-friendly and efficient synthesis of nitrones is presented by condensation of an equimolar amount of aldehydes and N-substituted hydroxylamine hydrochlorides in glycerol as a recyclable solvent-catalyst. This novel protocol provides rapid and mild access to a series of nitrone derivatives in good to excellent yields in the absence of catalyst and base. Graphic abstractSYNOPSIS In this
Photochemically-induced C–C bond formation between tertiary amines and nitrones
作者:Kennosuke Itoh、Ryo Kato、Daito Kinugawa、Hideaki Kamiya、Ryuki Kudo、Masayuki Hasegawa、Hideaki Fujii、Hiroyuki Suga
DOI:10.1039/c5ob01277e
日期:——
organophotosensitizer and photoirradiation was highly effective in accelerating addition reactions. Several nitrones and tertiary amines were successfully utilized to give β-amino hydroxylamines in good yield. Highly regioselective generation of primary α-aminoalkyl radicals based on Lewis's stereoelectronic rule and diastereoselective addition reactions of primary α-aminoalkyl radicals with nitrones were successfully
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.
Application of diethyl ethynephosphonate for the synthesis of 3-phosphonylated β-lactams via Kinugasa reaction
作者:Marcin K. Kowalski、Grzegorz Mlostoń、Emilia Obijalska、Heinz Heimgartner
DOI:10.3998/ark.5550190.p009.660
日期:——
The easily available diethyl ethynylphosphonate reacts with diverse aldonitrones under Kinugasareaction conditions at room temperature, providing 3-phosphonylated beta-lactams in good yields. In all cases, the reaction led to the trans-isomer exclusively. The trans-configuration was assigned based on 1H-NMR spectroscopic analysis.