Synthesis of Pyrazoles Utilizing the Ambiphilic Reactivity of Hydrazones

Matsuzaki, Haruo; Takeda, Norihiko; Yasui, Motohiro; Ito, Yuta; Konishi, Keiji; Ueda, Masafumi

doi:10.1021/acs.orglett.0c03465

Cited by 19 publications

(5 citation statements)

References 58 publications

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“…The synthesis of multisubstituted pyrazoles from the reaction of 1,2-diaza-1,3-dienes with conjugated hydrazones under acid conditions provides a new synthetic tool for preparing biologically active compounds [ 38 ]. In this reaction, 1,2-diaza-1,3-dienes 47 were generated in situ by β-protonation of α,β-unsaturated hydrazones 48 .…”

Section: Synthesis Of Heterocycles From 12-diaza-13-dienesmentioning

confidence: 99%

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

et al. 2022

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Many heterocyclic compounds can be synthetized using diaza-1,3-butadienes (DADs) as key structural precursors. Isolated and in situ diaza-1,3-butadienes, produced from their respective precursors (typically imines and hydrazones) under a variety of conditions, can both react with a wide range of substrates in many kinds of reactions. Most of these reactions discussed here include nucleophilic additions, Michael-type reactions, cycloadditions, Diels–Alder, inverse electron demand Diels–Alder, and aza-Diels–Alder reactions. This review focuses on the reports during the last 10 years employing 1,2-diaza-, 1,3-diaza-, 2,3-diaza-, and 1,4-diaza-1,3-butadienes as intermediates to synthesize heterocycles such as indole, pyrazole, 1,2,3-triazole, imidazoline, pyrimidinone, pyrazoline, -lactam, and imidazolidine, among others. Fused heterocycles, such as quinazoline, isoquinoline, and dihydroquinoxaline derivatives, are also included in the review.

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Section: Synthesis Of Heterocycles From 12-diaza-13-dienesmentioning

confidence: 99%

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

et al. 2022

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“…Unstable geminal azohydroperoxides [15] are formed as a result of hydrazone autoxidation by molecular oxygen [16][17][18][19]. In general, free-radical functionalization of hydrazones with the formation of azocompounds is less developed compared to methods based on electrophilic attack of hydrazone carbon atoms, such as Michael-type reactions [20][21][22][23], chlorination [24], alkoxylation, or cyanation [25]. Geminal azoacetates are synthesized by the oxidation of hydrazones with Pb(OAc) 4 [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

C–O Coupling of Hydrazones with Diacetyliminoxyl Radical Leading to Azo Oxime Ethers—Novel Antifungal Agents

Budnikov,

Krylov,

Shevchenko

et al. 2023

Molecules

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Selective oxidative C–O coupling of hydrazones with diacetyliminoxyl is demonstrated, in which diacetyliminoxyl plays a dual role. It is an oxidant (hydrogen atom acceptor) and an O-partner for the oxidative coupling. The reaction is completed within 15–30 min at room temperature, is compatible with a broad scope of hydrazones, provides high yields in most cases, and requires no additives, which makes it robust and practical. The proposed reaction leads to the novel structural family of azo compounds, azo oxime ethers, which were discovered to be highly potent fungicides against a broad spectrum of phytopathogenic fungi (Venturia inaequalis, Rhizoctonia solani, Fusarium oxysporum, Fusarium moniliforme, Bipolaris sorokiniana, Sclerotinia sclerotiorum).

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“…A literature survey reveals that several reported methods for the synthesis of Pyrazole unit generally synthesized i.e using the 3 component coupling reaction of aldehydes, 1,3-dicarbonyls, and diazo compounds, as well as tosyl hydrazones, rhodium-catalyzed addition-cyclization of hydrazines with alkynes 21 cyclic enol triflates and an elaborated set of diazoacetates 22 hydrazones and β-protonation/nucleophilic addition/aromatization sequence. 23 A copper-mediated cyclization, trifluoromethylation, and detosylation. 24 Potassium 1,1,3,3-tetranitropropane treated readily with various (hetero)arylamines.…”

Section: Introductionmentioning

confidence: 99%