Stereoselective Synthesis of Novel 4,5-Epoxy-1,2-oxazin-6-ones and α,β-Epoxy-γ-amino Acids from β-Lithiated Oxazolinyloxiranes and Nitrones
摘要:
A stereoselective synthesis of 9,10-epoxy-1,6-dioxa-4,7-diazaspiro[4,5] decanes has been developed on the basis of the addition of beta-lithiated oxazolinyloxiranes to nitrones. Conversion of these spirocyclic derivatives into 4,5-epoxy-1,2-oxazin-6-ones and successively into alpha,beta-epoxy-amino gamma- acids, alpha-hydroxy-gamma-amino acids, and gamma-butyrolactams is described.
Electronic effects in 1,3-dipolar cycloaddition reactions of N-alkyl and N-benzyl nitrones with dipolarophiles
作者:Andrei Bădoiu、E. Peter Kündig
DOI:10.1039/c1ob06144e
日期:——
1,3-Dipolar cycloadditions afforded fast access to isoxazolidines bearing N-alkyl or N-benzyl substituents. The electronic properties of the substituents in the nitrones define the activity of the dipoles and modulate diastereoselectivity in the non-catalyzed reactions. Using a chiral one-point binding ruthenium Lewis acid catalyst, products were obtained in good yields and with excellent regio-, diastereo-
A simple and efficient stereoselective synthesis of polysubstituted beta,gamma-epoxyhydroxylamines and 4-hydroxyalkyl-1,2-oxazetidines, based on the addition of alpha-lithiated aryloxiranes to nitrones and subsequent cyclization of the corresponding intermediates in a 4-exo-tet mode, is described.
Iridium(III)-Catalyzed C–H Amidation of Nitrones with Dioxazolones
作者:Xia Mi、Weisheng Feng、Chao Pi、Xiuling Cui
DOI:10.1021/acs.joc.9b00300
日期:2019.5.3
efficiently achieved through Ir(III)-catalyzed direct C–H amidation of nitrones with good to excellent yields and tolerance of broad functional groups. This reaction smoothly proceeded at roomtemperature in the absence of acid or base in a short reaction time. Carbon dioxide was generated as the sole byproduct, thus providing an environmentally benign amidation process. The title products could be efficiently
Synthesis of Enantiomerically Enriched Oxazolinyl[1,2]Oxazetidines
作者:Renzo Luisi、Vito Capriati、Saverio Florio、Eliana Piccolo
DOI:10.1021/jo035360u
日期:2003.12.1
The first stereoselective synthesis of oxazolinyl[1,2]oxazetidines based on the reaction of lithiated 2-(1-chloroethyl)-2-oxazolines with nitrones is described. Highly enantioenriched oxazolinyl[1,2]oxazetidines have also been prepared starting from a 1:1 diastereomeric mixture of optically active 2-(1-chloroethyl)-2-oxazolines.
Substituent effects on ESR parameters of α-phenyl-N-tert-butylnitrone spin adducts. Resolution enhancement and mass spectrometry
作者:Kai Pan、Chiou-Rong Lin、Tong-Ing Ho
DOI:10.1002/mrc.1260310705
日期:1993.7
The combination of high‐performance liquid chromatography (HPLC) and ESR spectrometry was used to isolate the free radicals produced by the reaction of a Grignard reagent with 15 substituted α‐Phenyl‐N‐tert‐butylnitrone. Long‐range hyperfine splitting constants (hfsc) were obtained by the resolution enhancement method. Linear correlation studies between hfsc and Hammett σp constants are reported. Dual‐parameter