PhIO/Et<sub>3</sub>N ⋅ 3HF-Mediated Formation of Fluorinated 2<i>H</i>-Azirines via Domino Fluorination/Azirination Reaction of Enamines
作者:Yong Zhang、Xiaoyuan Zhao、Chen Zhuang、Senlin Wang、Daisy Zhang-Negrerie、Yunfei Du
DOI:10.1002/adsc.201800124
日期:2018.6.5
enaminones were converted to the biologically interesting fluorinated 2H‐azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ⋅ 3HF in 1,2‐dichroloethane, which features the hypervalent iodine reagents‐mediated introduction of fluorine atom and formation of the 2H‐azirine skeleton under metal‐free conditions. The domino reaction is postulated to proceed via a PhIF2‐mediated oxidative
Fluorination of 4-nitroisoxazoline salts. Synthesis of 4-fluoro-4-nitroisoxazolines and 4-fluoroisoxazoles
作者:G. Kh. Khisamutdinov、L. V. Okhlobystina、A. A. Fainzil’berg
DOI:10.1007/s11172-009-0300-3
日期:2009.10
Methods for the synthesis of hitherto unknown 4-fluoro-4-nitroisoxazolines by fluorination of 4-nitroisoxazoline salts with FClO3 in MeOH and 4-fluoroisoxazoles by treatment of fluoronitroisoxazolines bearing the hydrogen atom bound to the C(5) atom of the isoxazole ring with MeONa in MeOH were developed.
Fluorine-alkoxy group exchangereactions of fluorinated isoxazoline derivatives promoted by Lewis acids to give various 5-alkoxylated 4,4-difluoroisoxazolines via SN1 type processes in good to excellent yields are reported. Sterically demanding phenol substrates such as 2,6-diphenylphenol gave novel aryl substituted products via electrophilic aromatic substitution.
2-Fluoro-1,3-diketones react with phenylhydrazine to yield ring-fluorinated pyrazoles in high yield. An isoxazole is produced when 2-fluoro-1,3-diphenyl-1,3-propandione is treated with hydroxylamine hydrochloride.
Direct Synthesis of 4-Fluoroisoxazoles through Gold-Catalyzed Cascade Cyclization–Fluorination of 2-Alkynone <i>O</i>-Methyl Oximes
A tandem protocol for the synthesis of fluorinated isoxazoles has been developed via catalytic intramolecular cyclizations of 2-alkynone O-methyl mimes and ensuing fluorination. The reactions proceed smoothly at room temperature in the presence of 5 mol % of (IPr)AuCl, 5 mol % of AgOTs, 2.5 equiv of Selectfluor, and 2 equiv of NaHCO3. This process features an efficient one-pot cascade route to fluoroisoxazoles with high yields and high selectivity under mild reaction conditions.