Origins of Stereoselectivity in the Oxido-Alkylidenation of Alkynes
作者:Daniel P. Canterbury、Alison J. Frontier、Joann M. Um、Paul H.-Y. Cheong、Dahlia A. Goldfeld、Richard A. Huhn、K. N. Houk
DOI:10.1021/ol8019154
日期:2008.10.16
alkynes is described. The three-step sequence involves the 1,3-dipolarcycloaddition of a nitrone and an alkynoate, oxidation of the resulting isoxazoline, and stereoselective extrusion of nitrosomethane. Quantum mechanical calculations identified the interactions of R3 with the oxidant and the preferred conformation of a diradicalintermediate as major factors controlling the stereoselectivity of the
Acid-Catalyzed 1,3-Dipolar Cycloaddition of 2<i>H</i>-Azirines with Nitrones: An Unexpected Access to 1,2,4,5-Tetrasubstituted Imidazoles
作者:Anikó Angyal、András Demjén、János Wölfling、László G. Puskás、Iván Kanizsai
DOI:10.1021/acs.joc.9b03288
日期:2020.3.6
The first 1,3-dipolarcycloaddition of 2H-azirines with nitrones, a straightforward approach toward the regioselective synthesis of 1,2,4,5-tetrasubstituted imidazoles, is reported. This trifluoroacetic acid-catalyzed protocol tolerates a broad range of aliphatic and aromatic substrates, offering an efficient access to highly diverse, multisubstituted imidazoles in isolated yields up to 83% under mild
4-Dimethylaminopyridine-Mediated [3+3] Cycloaddition of Aza-oxyallyl Cations and Nitrones
作者:Qianfa Jia、Dongli Li、Ming Lang、Kun Zhang、Jian Wang
DOI:10.1002/adsc.201700415
日期:2017.11.10
A new 4‐dimethylaminopyridine (DMAP)‐mediated [3+3] cycloaddition reaction of in situ‐ generated aza‐oxyallylcations with nitrones is reported. This simple and efficient method delivers a series of new motifs in good to excellent yields under mild conditions.
Lewis Acid Catalyzed Annulation of Nitrones with Oxiranes, Aziridines, and Thiiranes
作者:Stalin R. Pathipati、Vipender Singh、Lars Eriksson、Nicklas Selander
DOI:10.1021/acs.orglett.5b02195
日期:2015.9.18
Lewis acid catalyzed annulation of three-membered heterocycles with nitrones has been developed. Oxiranes, aziridines, and thiiranes were used as substrates for the synthesis of various six-membered heterocycles using Al or In catalysts. This catalytic protocol demonstrates a broad substrate scope and provides access to new structural motifs in high yields and in excellent selectivity under mild reaction
Facile synthesis of (polyfluoro)alkanesulfinyl 4-isoxazolines: a stepwise solvent- and catalyst-free approach or a one-pot process in water
作者:Tian-Ming Liao、Wen-Jiang Ma、Yu-Ning Gao、Ming Bian、Min Jiang、Jin-Tao Liu、Hui-Yu Chen、Zhen-Jiang Liu
DOI:10.1039/d3gc00557g
日期:——
protocols were reported for the synthesis of a wide range of polyfluoroalkanesulfinyl or alkylsulfinyl 4-isoxazolines. A variety of aldehyde and ketone derived nitrones reacted with α-alkynyl sulfoxides under catalyst- and solvent-freeconditions at roomtemperature to provide a series of polyfluoroalkanesulfinyl or alkylsulfinyl 4-isoxazolines with high efficiency. The synthesis of these sulfinyl 4-isoxazolines