[2 + 2 + 1] Cycloaddition of <i>N</i>-tosylhydrazones, <i>tert</i>-butyl nitrite and alkenes: a general and practical access to isoxazolines

Ma, Liang; Jin, Feng; Cheng, Xionglve; Tao, Suyan; Jiang, Gangzhong; Li, Xingxing; Yang, Jinwei; Bao, Xiaoguang; Wan, Xiaobing

doi:10.1039/d1sc02352g

Cited by 17 publications

(6 citation statements)

References 151 publications

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“…In the following edge article from 2021, a new type of CuCl 2 -catalyzed [2 + 2 + 1] cycloaddition leading to isoxazolines was presented— Scheme 283 [ 314 ]. Significantly, the RCNOs are not involved in the reaction method.…”

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

confidence: 99%

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

et al. 2023

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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.

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

confidence: 99%

“… Syntheses of 3,5-disubstituted isoxazolines from in situ-generated nitronates [ 314 ]. Examples of biologically important compounds.…”

Section: Figures and Schemesmentioning

confidence: 99%

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

et al. 2023

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“… Strategy for the synthesis of skeleton-fused isoxazole/isoxazoline. (HAT: Hydrogen Atom Transfer) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. …”

Section: Figures and Schemesmentioning

confidence: 99%

“…Wan, X.-B. et al reported the graceful cycloaddition reactions for the synthesis of isoxazoles from diazo compounds or N -tosylhydrazones with alkenes or β -keto esters activated by tert -butyl nitrite [ 29 , 30 , 31 ]. These approaches are robust and can deliver fully substituted isoxazoles.…”

Section: Introductionmentioning

confidence: 99%

tert-Butyl Nitrite-Induced Radical Nitrile Oxidation Cycloaddition: Synthesis of Isoxazole/Isoxazoline-Fused Benzo 6/7/8-membered Oxacyclic Ketones

Cao,

Yue

et al. 2024

Molecules

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A practical metal-free and additive-free approach for the synthesis of 6/7/8-membered oxacyclic ketone-fused isoxazoles/isoxazolines tetracyclic or tricyclic structures is reported through Csp3–H bond radical nitrile oxidation and the intramolecular cycloaddition of alkenyl/alkynyl-substituted aryl methyl ketones. This convenient approach enables the simultaneous formation of isoxazole/isoxazoline and 6/7/8-membered oxacyclic ketones to form polycyclic architectures by using tert-butyl nitrite (TBN) as a non-metallic radical initiator and N–O fragment donor.

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“…This feature of isoxazole makes it a key pharmaceutical fragment in many drugs [ 47 , 48 , 49 ]. In recent years, tert -butyl nitrite (TBN) has acted as a metal-free radical initiator and source of N-O [ 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ], which has attracted extensive attention in the construction of isoxazoles [ 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 ]. Despite these excellent methods, there are few reports on the construction of skeletal cores containing isoxazole and tricyclic quinazoline alkaloids or their derivatives.…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of Isoxazole-Fused Tricyclic Quinazoline Alkaloid Derivatives via Intramolecular Cycloaddition of Propargyl-Substituted Methyl Azaarenes under Metal-Free Conditions

et al. 2023

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A practical method was developed for the convenient synthesis of isoxazole-fused tricyclic quinazoline alkaloids. This procedure accesses diverse isoxazole-fused tricyclic quinazoline alkaloids and their derivatives via intramolecular cycloaddition of methyl azaarenes with tert-butyl nitrite (TBN). In this method, TBN acts as the radical initiator and the source of N–O. Moreover, this protocol forms new C–N, C–C, and C–O bonds via sequence nitration and annulation in a one-pot process with broad substrate scope and functionalization of natural products.

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[2 + 2 + 1] Cycloaddition of N-tosylhydrazones, tert-butyl nitrite and alkenes: a general and practical access to isoxazolines

Abstract: N-Tosylhydrazones have proven to be versatile synthons over the past several decades. However, to our knowledge, the construction of isoxazolines based on N-tosylhydrazones has not been examined. Herein, we report...

Cited by 17 publications

References 151 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

tert-Butyl Nitrite-Induced Radical Nitrile Oxidation Cycloaddition: Synthesis of Isoxazole/Isoxazoline-Fused Benzo 6/7/8-membered Oxacyclic Ketones

One-Pot Synthesis of Isoxazole-Fused Tricyclic Quinazoline Alkaloid Derivatives via Intramolecular Cycloaddition of Propargyl-Substituted Methyl Azaarenes under Metal-Free Conditions

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