Thermoinduced Free-Radical C–H Acyloxylation of Tertiary Enaminones: Catalyst-Free Synthesis of Acyloxyl Chromones and Enaminones

Guo, Yanhui; Xiang, Yunfeng; Li, Wei; Wan, Jie‐Ping

doi:10.1021/acs.orglett.8b01536

Cited by 97 publications

(29 citation statements)

References 85 publications

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“…While tertiary enaminones have been previously disclosed with highly enriched transformation pathways in different organic reactions, [16] it is desirable that such enaminones may also be used for the synthesis of 3-unsubstituted 4sulfonyl pyrazoles by using these typical N,N-dimethyl enaminones as substrates. Herein, we report the practical domino reactions of N,N-dimethyl enaminones and sulfonyl hydrazines featured with domino metal-free CÀ H elaboration [17] and pyrazole annulation for the synthesis of 4-sulfonyl pyrazoles without substituent in the C3 site.…”

Section: Introductionmentioning

confidence: 99%

Transition Metal‐free C−H Sulfonylation and Pyrazole Annulation Cascade for the Synthesis of 4‐Sulfonyl Pyrazoles

2020

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A practical protocol for the synthesis of 4-sulfonyl pyrazoles via the reactions of readily available N,N-dimethyl enaminones and sulfonyl hydrazines has been developed via the catalysis of molecular iodine in the presence of TBHP and NaHCO 3 at room temperature. The pyrazole products have been constructed via the tandem C(sp 2 )À H sulfonylation and a pyrazole annulation without employing any transition metal catalyst or reagent, thus providing a practical new method for the synthesis of the novel pyrazoles bearing a sulfonyl side chain in the heterocycle.

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Section: Introductionmentioning

confidence: 99%

Transition Metal‐free C−H Sulfonylation and Pyrazole Annulation Cascade for the Synthesis of 4‐Sulfonyl Pyrazoles

2020

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“…Therefore, the isoflavonoids are hitherto typical targets which are not accessible by C−H bond coupling. Actually, the synthesis of 3‐vinyl, 3‐perfluoroalkyl, 3‐alkynyl, 3‐alkyl, 3‐chalcogenyl 3‐acyloxyl chromones, etc, have been successively realized by coupling the C(sp 2 )−H bond of chromones or proper precursors, but never equivalent arylation. These known results confirm the challenge of synthesizing isoflavonoids by C−H arylation.…”

Section: Methodsmentioning

confidence: 99%

“…[10] Therefore, the isoflavonoids are hitherto typical targets whicha re not accessible by CÀHb ondc oupling. Actually,t he synthesis of 3-vinyl, [11] 3-perfluoroalkyl, [12] 3-alkynyl, [13] 3-alkyl, [14] 3-chalcogenyl [15] 3-acyloxylc hromones, [16] etc, have been successively realized by couplingt he C(sp 2 )ÀHb ond of chromones or properp recursors, but never equivalent arylation. These known resultsc onfirm the challenge of synthesizing isoflavonoids by CÀHa rylation.T herefore, it is inarguably significant to establish an alternative coupling method for isoflavonoid synthesis by directly transforming the raw CÀHb ond and avoidst he aforementioned shortcomings of the CÀXbond-based cross coupling.…”

Section: And Organic Chemistrymentioning

confidence: 99%

Transient and Recyclable Halogenation Coupling (TRHC) for Isoflavonoid Synthesis with Site‐Selective Arylation

Wan

Wang

2019

Chemistry A European J

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A transient and recyclable C−H iodination has been designed for the synthesis of isoflavonoids through the domino reactions of o‐hydroxyphenyl enaminones and aryl boronic acids in the presence of catalytic KI and Pd catalyst. Instead of the conventional cross‐coupling strategy employing pre‐halogenated substrates, this method transforms raw C−H bond by means of a transient C−H halogenation to smoothly relay the subsequent C‐arylation. Consequently, such a method avoids the pre‐functionalization for C−halogen bond installation as well as the generation of stoichiometric halogen‐containing waste following the cross‐coupled product, disclosing an intriguing new coupling protocol to forge the C−C bond in the virgin area between classical C−X (X=halogen) bond cross coupling and the C−H activation.

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“…However, efficient synthetic methods for the synthesis of such compounds were rare. Recently, by using enaminones 1 and aroyl peroxides 73 , Wan et al . disclosed the one‐step method toward the synthesis of 3‐acyloxyl chromones under catalyst‐free conditions.…”

Section: Reactions Involving C−o Bond Formationmentioning

confidence: 99%

C3‐Functionalized Chromones Synthesis by Tandem C−H Elaboration and Chromone Annulation of Enaminones

Wan

2019

Asian J Org Chem

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Chromone is a heterocyclic entity presents in a number of natural products, clinical pharmaceuticals, as well as molecules with enriched biological functions. As cuttingedge area, the synthesis of chromones has seen spectacular progress over the past decade. Among the available synthetic modes toward chromone scaffolds, the annulation of orthohydroxyphenyl functionalized N,N-disubstituted enaminones has turned out to be one of the most reliable and practical ones. By combining this annulation with the featured transformation of the vinyl α-CÀ H bond in the enaminone structure, a large number of tandem reactions providing structurally diverse chromones with C3-functionalization have been recently realized. As a practical strategy in the synthesis of valuable heterocyclic molecules and an important branch in the enaminone-based organic synthesis, such synthetic reactions are highly instructive for organic chemistry and many other disciplines related to this heterocyclic moiety. Herein, we present for the first time the research advances on the synthesis of C3-functionalized chromones via tandem vinyl CÀ H bond elaboration and chromone annulation of ortho-hydroxyphenyl functionalized tertiary enaminones. 2 3 4 5 6 7 8

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Thermoinduced Free-Radical C–H Acyloxylation of Tertiary Enaminones: Catalyst-Free Synthesis of Acyloxyl Chromones and Enaminones

Cited by 97 publications

References 85 publications

Transition Metal‐free C−H Sulfonylation and Pyrazole Annulation Cascade for the Synthesis of 4‐Sulfonyl Pyrazoles

Transition Metal‐free C−H Sulfonylation and Pyrazole Annulation Cascade for the Synthesis of 4‐Sulfonyl Pyrazoles

Transient and Recyclable Halogenation Coupling (TRHC) for Isoflavonoid Synthesis with Site‐Selective Arylation

C3‐Functionalized Chromones Synthesis by Tandem C−H Elaboration and Chromone Annulation of Enaminones

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