TEMPO‐Mediated Selective Synthesis of Isoxazolines, 5‐Hydroxy‐2‐isoxazolines, and Isoxazoles via Aliphatic <i>δ</i>‐C(sp3)‐H Bond Oxidation of Oximes

Mondal, Santanu; Biswas, Sourabh; Ghosh, Krishna Gopal; Sureshkumar, Devarajulu

doi:10.1002/asia.202100572

Cited by 8 publications

(6 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3,5-di- and 3,5,5-trisubstituted 2-isoxazolines, including 5-hydroxy-2-isoxazolines, were prepared from oximes using inexpensive inorganic reagents, namely TEMPO and K 2 S 2 O 8 or TEMPO and PhI(OAc) 2 as oxidation systems—as reported in an article from 2021 ( Scheme 299 ) [ 332 ].…”

Section: Methods Of 2-isoxazolines Synthesis Other Than Dipolar Cyclo...mentioning

confidence: 99%

See 1 more Smart Citation

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

et al. 2023

View full text Add to dashboard Cite

The involvement of 1,3-dipolar cycloaddition (1,3-DP), double bond migration, metathesis, and nitrile oxide (including in situ-generated nitrile oxide) as dipoles, together with the C=C bond containing dipolarophiles, in the syntheses of 2-isoxazolines is presented. Methods for synthesizing isoxazolines (other than 1,3-DP cycloaddition) were also presented briefly. Various methods of nitrile oxide preparation, especially in situ-generated procedures, are presented. Special attention was paid to the application of various combinations of 1,3-DP cycloaddition with double bond migration (DBM) and with alkene metathesis (AM) in the syntheses of trisubstituted isoxazolines. Allyl compounds of the type QCH2CH=CH2 (Q = ArO, ArS, Ar, and others) play the role of dipolarophile precursors in the combinations of DPC mentioned, DBM and AM. Mechanistic aspects of cycloadditions, i.e., concerted or stepwise reaction mechanism and their regio- and stereoselectivity are also discussed from experimental and theoretical points of view. Side reactions accompanying cycloaddition, especially nitrile oxide dimerization, are considered. 2-Isoxazoline applications in organic synthesis and their biological activity, broad utility in medicine, agriculture, and other fields were also raised. Some remaining challenges in the field of 1,3-DP cycloaddition in the syntheses of isoxazolines are finally discussed.

show abstract

Section: Methods Of 2-isoxazolines Synthesis Other Than Dipolar Cyclo...mentioning

confidence: 99%

“… Syntheses of 3,5-disubstituted isoxazolines via aliphatic δ-C(sp 3 )-H bond oxidation of oximes [ 332 ]. a = TEMPO, K 2 S 2 O 8 , MeCN, rt to 50 °C, 24 h to 48 h; b = TEMPO, PhI(OAc) 2 , MeCN, rt, N 2 , 24 h; up to 81% yield (for A), up to 89% yield (for B).…”

Section: Figures and Schemesmentioning

confidence: 99%

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

et al. 2023

View full text Add to dashboard Cite

show abstract

“…19 Later, in 2021, a method for the selective synthesis of 2-isoxazolines bearing a quaternary center was developed by Sureshkumar et al with the judicious combination of TEMPO and oxidants. 20 Herein, we report an efficient K 2 CO 3 -mediated intramolecular oxa-Michael cyclization reaction of ,-diarylated ,unsaturated ketoximes for the synthesis of densely arenesubstituted 2-isoxazolines having a quaternary center (Scheme 1c).…”

Section: Paper Synthesismentioning

confidence: 99%

“…1 H NMR (500 MHz, CDCl 3 ):  = 7.69 (dd, J = 6.5, 3.0 Hz, 2 H), 7.46 (d, J = 7.6 Hz, 2 H), 7.43-7.39 (m, 5 H), 7.36 (t, J = 7.6 Hz, 2 H), 7.30 (dd, J = 14.6, 7.9 Hz, 3 H), 3.96 (q, J = 16.5 Hz, 2 H). 13 20 Yield: 94% (112 mg); white solid. 1 H NMR (500 MHz, CDCl 3 ):  = 7.73-7.64 (m, 2 H), 7.52 (d, J = 7.5 Hz, 2 H), 7.43-7.35 (m, 5 H), 7.29 (t, J = 7.3 Hz, 1 H), 3.51 (q, J = 16.4 Hz, 2 H), 1.83 (s, 3 H).…”

Section: R S Jat Et Almentioning

confidence: 99%

K2CO3-Mediated Intramolecular Oxa-Michael Cyclization of α,β-Unsaturated Ketoximes: Synthesis of Densely Arene-Substituted 2-Isoxazolines Bearing a Quaternary Center

Bhanuchandra,

Jat,

Kothapalli

2024

Synthesis

View full text Add to dashboard Cite

An efficient K2CO3-mediated intramolecular oxa-Michael cyclization of β,β-diarylated-α,β-unsaturated ketoximes has been described. This methodology features arene-rich 2-isoxazoline derivatives bearing one quaternary center in excellent yields with operationally simple experimental procedure. The deuterium scrambling experiments were carried out to shed light on the reaction pathway. To further demonstrate the synthetic utility of the method, a large-scale synthesis and Ullmann-type C-N bond formation reaction between pyrazole and dibrominated-isoxazoline have been performed.

show abstract

“…Experimental procedures, additional discussion, copies of 1 H and 13 C NMR spectra (.pdf), crystallographic data (.cif). The authors have cited additional references within the Supporting Information [25–60] …”

Section: Supporting Informationmentioning

confidence: 99%

Gold‐Catalyzed Cyclization of Yndiamides with Isoxazoles via α‐Imino Gold Fischer Carbenes

Tong,

Smith,

Pickford

et al. 2023

Chemistry A European J

View full text Add to dashboard Cite

Gold catalysis is an important method for alkyne functionalization. Here we report the gold‐catalyzed formal [3+2] aminative cyclization of yndiamides and isoxazoles in a direct synthesis of polysubstituted diaminopyrroles, which are important motifs in drug discovery. Key to this process is the formation, and subsequent cyclization, of an α‐imino gold Fischer carbene, which represents a new type of gold carbene intermediate. The reaction proceeds rapidly under mild conditions, with high regioselectivity being achieved by introducing a subtle steric bias between the nitrogen substituents on the yndiamide. DFT calculations revealed that the key to this regioselectivity was the interconversion of isomeric gold keteniminiun ions via a low‐barrier π‐complex transition state, which establishes a Curtin‐Hammett scenario for isoxazole addition. By using benzisoxazoles as substrates, the reaction outcome could be switched to a formal [5+2] cyclization, leading to 1,4‐oxazepines.

show abstract

TEMPO‐Mediated Selective Synthesis of Isoxazolines, 5‐Hydroxy‐2‐isoxazolines, and Isoxazoles via Aliphatic δ‐C(sp3)‐H Bond Oxidation of Oximes

Cited by 8 publications

References 40 publications

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

Nitrile Oxide, Alkenes, Dipolar Cycloaddition, Isomerization and Metathesis Involved in the Syntheses of 2-Isoxazolines

K2CO3-Mediated Intramolecular Oxa-Michael Cyclization of α,β-Unsaturated Ketoximes: Synthesis of Densely Arene-Substituted 2-Isoxazolines Bearing a Quaternary Center

Gold‐Catalyzed Cyclization of Yndiamides with Isoxazoles via α‐Imino Gold Fischer Carbenes

Contact Info

Product

Resources

About