Strategies and Methods for the Synthesis of 2‐Pyrazolines: Recent Developments (2012–2022)

Advanced Synthesis & Catalysis, Год журнала: 2023, Номер 365(12), С. 1934 - 1969

Опубликована: Май 22, 2023

Abstract 2‐Pyrazolines are important five‐membered heterocycles, containing two adjacent nitrogen atoms. They can incorporate various functional groups and possess unique biological properties. Moreover, they have been used as useful building blocks. In recent years, the field of 2‐pyrazoline synthesis has experienced enormous progress. Novel strategies developed, many studies reporting improvements or adaptations existing protocols published, giving access to new functionalizations, unexplored structures, and/or enantioselective synthesis. This review summarizes progress made in synthetic methodologies during period from 2012 2022. The functionalization challenges capabilities, scopes limitations reactions, substitution patterns, mechanisms where appropriate, will be discussed.

Язык: Английский

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Synthesis of difluoromethylated spiropyrazolones via [3 + 2] cycloaddition of difluoroacetohydrazonoyl bromides with alkylidene pyrazolones

Organic & Biomolecular Chemistry, Год журнала: 2024, Номер 22(14), С. 2797 - 2812

Опубликована: Янв. 1, 2024

Highly functionalized fluoroalkyl spiropyrazolones are synthesized via an effective [3 + 2] cycloaddition of di/trifluoromethyl hydrazonoyl bromides and alkylidene pyrazolones in good yields.

Язык: Английский

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[3 + 2] Cycloaddition Reaction of Vinylsulfonium Salts with Hydrazonoyl Halides: Synthesis of Pyrazoles

The Journal of Organic Chemistry, Год журнала: 2024, Номер 89(14), С. 10066 - 10076

Опубликована: Июль 2, 2024

An efficient [3 + 2] cycloaddition reaction between in situ generated nitrile imines from hydrazonoyl halides and vinylsulfonium salts is developed. The are demonstrated to be a new class of partner for conduct the reaction. process provides concise method construction pyrazole derivatives under mild conditions with broad substrate scope, good product yields, high regioselectivity.

Язык: Английский

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Synthesis of Di/Trifluoromethyl Bis(1,2,4-triazoline)spiranes and 1,2,4-Triazoles via 1,3-Dipolar Cycloaddition of Nitrilimines and Carbodiimides

Organic & Biomolecular Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

An efficient strategy for constructing di/trifluoromethyl bis(1,2,4-triazoline)spiranes and 1,2,4-triazoles via 1,3-dipolar cycloaddition reaction of nitrilimines carbodiimides was developed. Various N-aryl acetohydrazonoyl bromides are well tolerated in the reaction, providing target products good regioselectivity yields. This method features simple operation, high efficiency mild conditions rapid synthesis complex fluoroalkylated nitrogen-rich spirocyclic compounds.

Язык: Английский

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Advances in the Synthesis of Heterocycles with Two and Three Heteroatoms using Hydrazonoyl Halides

Helvetica Chimica Acta, Год журнала: 2024, Номер 107(7)

Опубликована: Апрель 30, 2024

Abstract The review covers the results of studies published in literature on use hydrazonoyl halides synthesis five‐ (pyrazoles, thiazoles, triazoles, oxa‐ and thiadiazoles), six‐ (oxa‐ thiadiazines, indazoles, pyridazines, pyrazines, tetrazines) or seven‐membered (benzotriazepine) heterocycles. In formation these heterocycles, main intermediate stage reaction is situ generation nitrilimine, which enters into a cycloaddition with substituted acetylenes (including generated benzynes, naphthynes), allenes, activated olefins, anthranilic acid derivatives, organosulfur compounds (mercaptoaldehydes, mercaptocarboxylic acids) fused Examples are given heterocycles by replacing halogen atom from halide molecule nucleophilic group, followed exhaustive intramolecular cyclization target compound. There discussions reactions nitrilimine to synthesized Knoevenagel condensation product (from CH‐acid compounds, such as di‐ monocarbonyl dinitrile malonic acid) occurs, leading spiro‐linked conventional pyrazoles. Some syntheses biologically active representatives shown.

Язык: Английский

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Synthesis of Fully Substituted Difluoromethylpyrazoles by Cyclization of Difluoroacetohydrazonoyl Bromides with 2-Acylacetonitriles or Malononitrile

The Journal of Organic Chemistry, Год журнала: 2024, Номер 89(15), С. 10591 - 10602

Опубликована: Июль 12, 2024

A concise and efficient method for the construction of fully substituted difluoromethylpyrazoles is achieved by a cyclization reaction between difluoroacetohydrazonoyl bromides 2-acylacetonitrile or malononitrile. The features advantages such as mild conditions, broad substrate scope, good product yields, high regioselectivity.

Язык: Английский

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Fluorinated and Non-Fluorinated 1,4-Diarylpyrazoles via MnO2-Mediated Mechanochemical Deacylative Oxidation of 5-Acylpyrazolines

Molecules, Год журнала: 2022, Номер 27(23), С. 8446 - 8446

Опубликована: Дек. 2, 2022

A solvent-free two-step synthesis of polyfunctionalized pyrazoles under ball-milling mechanochemical conditions was developed. The protocol comprises (3 + 2)-cycloaddition in situ generated nitrile imines and chalcones, followed by oxidation the initially formed 5-acylpyrazolines with activated MnO2. second step proceeds via an exclusive deacylative pathway, to give a series 1,4-diarylpyrazoles functionalized fluorinated (CF3) or non-fluorinated (Ph, COOEt, Ac) substituent at C(3) heterocyclic ring. In contrast, MnO2-mediated model isomeric 4-acylpyrazoline proceeded low chemoselectivity, leading fully substituted pyrazole as major product dehydrogenative aromatization. presented approach extends scope known methods carried out organic solvents enables preparation pyrazoles, which are general interest medicine material sciences.

Язык: Английский

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Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

Beilstein Journal of Organic Chemistry, Год журнала: 2023, Номер 19, С. 1741 - 1754

Опубликована: Ноя. 15, 2023

Nitrogen-containing organofluorine derivatives, which are prepared using fluorinated building blocks, among the most important active fragments in various pharmaceutical and agrochemical products. This review focuses on reactivity, synthesis, applications of fluoromethylated hydrazones acylhydrazones. It summarizes recent methodologies that have been used for synthesis nitrogen-containing compounds.

Язык: Английский

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Design, Synthesis, Antifungal and Antibacterial Activities of Novel Difluoromethyl Pyrazole Derivatives

Russian Journal of General Chemistry, Год журнала: 2024, Номер 94(4), С. 963 - 968

Опубликована: Апрель 1, 2024

Язык: Английский

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Trifluoromethylated 4,5-Dihydro-1,2,4-triazin-6(1H)-ones via (3+3)-Annulation of Nitrile Imines with α-Amino Esters

Materials, Год журнала: 2023, Номер 16(2), С. 856 - 856

Опубликована: Янв. 16, 2023

The synthesis of two series monocyclic and bicyclic trifluoromethylated 4,5-dihydro-1,2,4-triazin-6(1H)-one derivatives based on (3+3)-annulation methyl esters derived from natural α-amino acids with in situ generated trifluoroacetonitrile imines has been described. devised protocol is characterized by a wide scope, easily accessible substrates, remarkable functional group tolerance, high chemical yield. In reactions chiral starting materials, no racemization at the stereogenic centers was observed respective enantiomerically pure products were obtained. Selected interconversions carried out under catalytic hydrogenation mild PTC oxidation conditions also demonstrated.

Язык: Английский

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