Trimethylsilyl trifluoromethanesulfonate-promoted cycloaddition of nitrones with silyl enol ethers: synthesis and reactivity of 5-siloxyisoxazohdines
作者:Chiara Camiletti、Dilip D. Dhavale、Luca Gentiluccia、Claudio Trombini
DOI:10.1039/p19930003157
日期:——
In the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf), the reaction of nitrones with silyl enolethers affords 5-siloxyisoxazolidines under mild conditions, in good to excellent yields. 5-Siloxyisoxazolidines can undergo chemoselective reductions to Manoich bases or N-hydroxy-1,3-amino alcohols, and, in the presence of TMSOTf, react with silylated carbon nucleophiles at the acetalic
Trimethylsilyl trifluoromethanesulfonate promoted [3 + 2] dipolar cycloaddition of nitrones and silyl enol ethers: an efficient route to 5-siloxyisoxazolidines
作者:Dilip D. Dhavale、Claudio Trombini
DOI:10.1039/c39920001268
日期:——
The reaction of silyl enolethers and nitrones, in the presence of trimethylsilyl trifluoromethanesulfonate, gives 5-siloxyisoxazolidines in excellent yield under fairly mild conditions.
[reaction: see text] Dicobalt octacarbonyl [Co(2)(CO)(8)] in acetonitrile at 75 degrees C triggers the cleavage of the N-O bond of 4-isoxazolines (1) to bring about the valence rearrangement to 2-acylaziridines (2). The isoxazolines were stable at 75 degrees C in the absence of the cobalt complex.
Synthesis of 2,3-Dihydroisoxazoles from Propargylic <i>N</i>-Hydroxylamines via Zn(II)-Catalyzed Ring-Closure Reaction
作者:Patrick Aschwanden、Doug E. Frantz、Erick M. Carreira
DOI:10.1021/ol006095r
日期:2000.7.1
A novel cyclization reaction of propargylic N-hydroxylamines to 2,3, 5-trisubstituted 2,3-dihydroisoxazoles in the presence of catalytic amounts (10 mol %) of ZnI(2) and DMAP is reported. The methodology provides a mild new approach to this useful class of substituted heterocycles that complements extant methods. The unique reactivity of the propargylic N-hydroxylamine substrates in the presence of
Synthesis of 4-Isoxazolines through Gold(I)-Catalyzed Cyclization of Propargylic <i>N</i>-Hydroxylamines
作者:B. Chandrasekhar、Sewon Ahn、Jae-Sang Ryu
DOI:10.1021/acs.joc.6b01499
日期:2016.8.5
New catalytic methods for the synthesis of 4-isoxazolines have been developed via catalytic intramolecularcyclizations of propargylic N-hydroxylamines. The reactions proceed rapidly in less than 1 h at room temperature in the presence of 5 mol % (PPh3)AuCl/5 mol % AgOTf or 5 mol % (PPh3)AuNTf2. This process features an efficient route to 4-isoxazolines with high yields, short reaction times, and mild