20822-00-8Relevant articles and documents
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Barnes et al.
, p. 276 (1954)
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Iron(iii)-catalyzed selective N-O bond cleavage to prepare tetrasubstituted pyridines and 3,5-disubstituted isoxazolines from: N -vinyl-α,β-unsaturated ketonitrones
Chen, Chun-Hua,Wu, Qing-Yan,Wei, Cui,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
supporting information, p. 2722 - 2729 (2018/06/29)
An iron(iii)-catalyst controlled cyclization and selective N-O bond cleavage of N-vinyl-α,β-unsaturated nitrones has been achieved under mild conditions to access tetrasubstituted pyridines and 3,5-disubstituted isoxazolines in moderate to good yields. The tetrasubstituted pyridines were afforded with FeCl3 as a catalyst while using FeCl3·6H2O combined with 1,10-phenanthroline delivered isoxazolines. The regioselectivity for cyclization of styrenyl groups in N-vinyl-α,β-unsaturated nitrones was completely different during the formation of pyridines and isoxazolines. A rational mechanism for the formation of pyridines and isoxazolines was proposed based on the further control experimental studies. The isoxazolines can be converted to a novel bidentate N-ligand over four steps and an epoxypyridine scaffold was obtained from N-vinyl nitrone when copper(ii) acetate in combination with the prepared bidentate N-ligand was used.
Base-Promoted [3+2]-Annulation of Oxime Esters and Aldehydes for Rapid Isoxazoline Formation
Huang, Huawen,Li, Feifei,Xu, Zhenhua,Cai, Jinhui,Ji, Xiaochen,Deng, Guo-Jun
supporting information, p. 3102 - 3107 (2017/09/13)
A base-promoted [3+2]-annulation of ketoxime esters and aldehydes is disclosed for the facile and rapid synthesis of 3,5-disubstituted and 3,4,5-trisubstituted isoxazolines. The key to our success is the pivalate leaving group of the oxime substrates, combined with cesium carbonate as promoter. This chemistry allows the assembly of a vast array of isoxazoline derivatives under simple base conditions in a method complementary to the classic isoxazoline formation via [3+2]-dipolar cycloaddition of nitrile oxides and olefins. It also represents a new reaction pattern involving electrophilic amination/N–O bond substitution. (Figure presented.).
