10557-78-5Relevant articles and documents
13C NMR spectroscopy of heterocycles: 3,5-diaryl-4-bromoisoxazoles
Yu, Jiayo,Edjah, Beatrice,Argueta-Gonzalez, Hector,Ross, Stephanie,Gaulden, Patrick,Shanderson, Ronald,Dave, Julia,Baumstark, Alfons L.
, p. 279 - 283 (2015)
A series of 3,5-diarylisoxazoles (1-9) underwent reaction with N-bromosuccinimide in acetic acid to yield the corresponding 3.5-diaryl-4-bromoisoxazoles (1Br-9Br) in low to moderate yield. The X-ray structure of 3-(4-chlorophenyl)-5-phenyl-4-bromoisoxazole showed torsion angles of ~40° and ~36° between the 3- and 5-aryl groups and the central ring system, respectively. Molecular modeling studies predicted the 3,5-phenylisoxazole ring system to be essentially coplanar and the 3,5-diphenyl groups of the 4-bromoisoxazole derivative to be twisted with torsional angles of 50° and 37°, respectively. Carbon-13 nuclear magnetic resonance (13C NMR) data of the 3,5-diaryl-4-bromoisoxazoles were obtained in dimethyl sulfoxide-d6 (DMSO-d6) at 50°C. Plots of the C4 chemical shift data for isoxazoles (1-9) vs. those for 4-bromoisoxazoles (1Br-9Br) showed a good linear correlation (r2 = 0.974) with a slope of 0.96. Substitution on the 3-aryl group had essentially no effect on the chemical shift for C4 of the 4-bromoisoxazole, whereas that on the 5-aryl group showed an excellent correlation with σ+ values. Despite the predicted torsion angle differences, distal transmission of substituent effects in the 4-bromo ring system was essentially analogous to that in the planar 3,5-diarylisoxazoles.
R4NHal/NOHSO4: A Usable System for Halogenation of Isoxazoles, Pyrazoles, and beyond
Bondarenko, Oksana B.,Karetnikov, Georgy L.,Komarov, Arseniy I.,Pavlov, Aleksandr I.,Nikolaeva, Svetlana N.
supporting information, p. 322 - 332 (2021/01/14)
A new convenient and versatile halogenating system (R4NHal/NOHSO4), giving straightforward and general access to halogenated 3,5-diaryl- and alkylarylisoxazoles, pyrazoles and electron-rich benzenes from the corresponding scaffolds, is suggested. The method provides excellent regioselectivity, scalability to the gram scale, and a broad scope for both aromatics and halogens. A three-step, one-pot reaction protocol was developed, and a series of 3,5-diaryl-4-haloisoxazoles has been efficiently synthesized from 1,2-diarylcyclopropanes under suggested nitrosating-halogenating conditions.
Isomerizable (: E / Z)-alkynyl- O -methyl oximes employing TMSCl-NCS in chlorinative cyclization for the direct synthesis of 4-chloroisoxazoles
Kaewsri, Wilailak,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
, p. 48666 - 48675 (2016/06/09)
For the first time, 4-chloroisoxazoles are directly synthesized in moderate to excellent yields from (E/Z)-alkynyl-O-methyl oximes via chlorinative cyclization. The synthesis employs the combination of N-chlorosuccinimide (NCS) and chlorotrimethylsilane (
