Tandem CuAAC/Ring Cleavage/[4 + 2] Annulation Reaction to Synthesize Dihydrooxazines and Conversion to 2-Aminopyrimidines

Yang, Weiguang; Zhao, Yu; Bu, Qingxia; Li, Li; Zhou, Baojing; Huang, Zunnan

doi:10.1021/acs.orglett.1c04179

Cited by 11 publications

(5 citation statements)

References 60 publications

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“…Informed by earlier studies, our present investigations began with efforts to prepare pyridin-4(1 H )-imine 4a via coupling of enaminone 1a , p -tosyl azide ( 3a ), and but-3-yn-2-one ( 2a )see Table . Initial screenings involved using DCE as solvent for a range of standard catalysts (Table , entries 1–10).…”

Section: Resultsmentioning

confidence: 99%

“…Based on the earlier literature, ,, a plausible mechanism for the formation of pyridin-4(1 H )-imines ( 4a ) from enaminone 1a , sulfonyl azide 2a , and terminal ynone 3a is illustrated in Scheme . The sulfonyl azide 2a and terminal ynone 3a are expected to take [3 + 2] cyclization to form the metalated triazole intermediate A (a CuAAC pathway).…”

Section: Resultsmentioning

confidence: 99%

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Chemoselectivity of the CuAAC/Ring Cleavage/Cyclization Reaction between Enaminones and α-Acylketenimine

Li,

Luo,

Luo

et al. 2024

J. Org. Chem.

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Ketenimines represent an important class of reactive species, useful synthetic intermediates, and synthons. However, in general, ketenimines preferentially undergoes nucleophilic addition reactions with hydroxyl and amino groups, and carbon functional groups remain a less studied subset of such systems. Herein, we develop a straightforward syntheses of pyridin-4(1H)-imines that is achieved by cyclization of a reacting enaminone unit with αacylketenimine which is generated from the reactions of sulfonyl azides and terminal ynones in situ (CuAAC/Ring cleavage reaction). The cascade process preferentially starts with the nucleophilic α-C of the enaminone unit instead of an amino group, attacking the electron-deficient central carbon of ketenimine, and the chemoselectivity unconventional products pyridin-4(1H)-imines were formed by intramolecular cyclization.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Chemoselectivity of the CuAAC/Ring Cleavage/Cyclization Reaction between Enaminones and α-Acylketenimine

Li,

Luo,

Luo

et al. 2024

J. Org. Chem.

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“…Informed by earlier studies [ 49 , 50 ], our present investigations began with efforts to prepare ethyl ( E )-3-(( E )-2-(tosylimino)pyridin-1(2 H )-yl)acrylate ( 4a ) via coupling of 2-aminopyridine ( 1a ,), ethyl propiolate ( 2a ) and p- tosyl azide ( 3a )—see Table 1 . The initial reactions were carried out at 60 °C in the presence of ferrocene [Fe(C 5 H 5 ) 2 ] and using DCE as solvent.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Pyridin-1(2H)-ylacrylates and the Effects of Different Functional Groups on Their Fluorescence

Yang,

Luo,

et al. 2023

Molecules

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While fluorescent organic materials have many potential as well as proven applications and so have attracted significant attention, pyridine–olefin conjugates remain a less studied subset of such systems. Herein, therefore, we report on the development of the straightforward syntheses of pyridin-1(2H)-ylacrylates and the outcomes of a study of the effects of substituents on their fluorescent properties. Such compounds were prepared using a simple, metal-free and three-component coupling reaction involving 2-aminopyridines, sulfonyl azides and propiolates. The fluorescent properties of the ensuing products are significantly affected by the positions of substituents on the cyclic framework, with those located in central positions having the greatest impact. Electron-withdrawing groups tend to induce blue shifts while electron-donating ones cause red shifts. This work highlights the capacity that the micro-modification of fluorescent materials provides for fine-tuning their properties such that they may be usefully applied to, for example, the study of luminescent materials.

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“…It has also been used for modifying the structure of natural products, drugs, and biological macromolecules [42][43][44]. Our group has delved into this area and utilized the CuAAC/ring cleavage reaction to synthesize pyridine derivates, fused heterocycles, coumarins, indoles, and other nitrogenated compounds [45][46][47][48][49].…”

Section: Introductionmentioning

confidence: 99%

An Oxidant-Free and Mild Strategy for Quinazolin-4(3H)-One Synthesis via CuAAC/Ring Cleavage Reaction

He,

Yang,

Luo

et al. 2023

Molecules

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An oxidant-free and highly efficient synthesis of phenolic quinazolin-4(3H)-ones was achieved by simply stirring a mixture of 2-aminobenzamides, sulfonyl azides, and terminal alkynes. The intermediate N-sulfonylketenimine underwent two nucleophilic additions and the sulfonyl group eliminated through the power of aromatization. The natural product 2-(4-hydroxybenzyl)quinazolin-4(3H)-one can be synthesized on a large scale under mild conditions with this method.

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Tandem CuAAC/Ring Cleavage/[4 + 2] Annulation Reaction to Synthesize Dihydrooxazines and Conversion to 2-Aminopyrimidines

Cited by 11 publications

References 60 publications

Chemoselectivity of the CuAAC/Ring Cleavage/Cyclization Reaction between Enaminones and α-Acylketenimine

Chemoselectivity of the CuAAC/Ring Cleavage/Cyclization Reaction between Enaminones and α-Acylketenimine

Synthesis of Pyridin-1(2H)-ylacrylates and the Effects of Different Functional Groups on Their Fluorescence

An Oxidant-Free and Mild Strategy for Quinazolin-4(3H)-One Synthesis via CuAAC/Ring Cleavage Reaction

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