Synthesis of novel isoxazole-containing pyrazolines and pyrazoles via cycloaddition and elimination/aromatization process

Huang, Hui; Pu, Yiru; Zhu, Dongyong; Yang, Joey; Liu, Changqun; Zhang, Xin; Tao, Fenggang; Li, Mei-Mei; Lü, Jun

doi:10.1016/j.tet.2022.133203

Cited by 5 publications

(2 citation statements)

References 25 publications

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“…A relatively low yield (55 %) is observed in the case of hydrazonoyl chloride 108 (Ar 1 = 3‐O 2 NC 6 H 4 ). In other reactions, the yields reach 70–99 % [91] . The subsequent reaction of aromatization/elimination of the oxazole fragment under the influence of SnCl 2 when heated in DMF at 100 “C leads to 1,3,4‐triarylpyrazoles [92] …”

Section: Syntheses Of Pyrazoles Triazoles Oxazoles Thiazoles Oxadiazo...mentioning

confidence: 99%

“…In other reactions, the yields reach 70 -99 %. [91] The subsequent reaction of aromatization/elimination of the oxazole fragment under the influence of SnCl 2 when heated in DMF at 100 "C leads to 1,3,4-triarylpyrazoles. [92] Of the many similar syntheses in this direction, as an example, we can also mention the preparation of biologically significant pyrazoles 111 by condensation of enaminone 112 with hydrazonoyl chloride 113 by boiling in xylene in the presence of triethylamine.…”

Section: Synthesis Of Pyrazoles By Reaction Of Nitrilimines With Acet...mentioning

confidence: 99%

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

Yamaletdinova,

Gataullin

2024

Helvetica Chimica Acta

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

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Section: Syntheses Of Pyrazoles Triazoles Oxazoles Thiazoles Oxadiazo...mentioning

confidence: 99%

Section: Synthesis Of Pyrazoles By Reaction Of Nitrilimines With Acet...mentioning

confidence: 99%

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

Yamaletdinova,

Gataullin

2024

Helvetica Chimica Acta

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Cyclic Deracemization of rac‐Sulfoxides via Alternating Biocatalytic Reduction and Light‐Dependent Oxidation Employing Eosin Y as Photocatalyst

Bierbaumer,

Glueck,

Winkler

et al. 2024

ChemCatChem

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The synergistic combination of biocatalysis and photocatalysis is emerging as powerful tool for the development of sustainable and atom‐efficient synthetic concepts facilitating an enormous portfolio of possible reactions which even goes beyond the capabilities found in nature. Here, a cyclic deracemization process is presented tailored for the synthesis of optically pure sulfoxides which are versatile structural motifs in asymmetric synthesis as well as in bioactive compounds. Enantioselective enzyme‐catalyzed reduction of rac‐sulfoxides was combined with a stereo‐unselective photocatalytic oxidation of the corresponding sulfide intermediate. The utilization of the readily accessible and rather inexpensive photocatalyst Eosin Y increases the usability of this synthetic method. To overcome the incompatibility between the photocatalyst Eosin Y and the biocatalytic step, the cyclic deracemization process was performed in a step‐wise fashion via alternated reduction in the darkness and oxidation under illumination. This modular system allowed precise adjustments of reaction parameters yielding the desired sulfoxide targets with up to >99% ee. Evaluation of the substrate scope including a range of structurally diverse molecules demonstrated its broad applicability.

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Recent progress in the synthesis of nitroisoxazoles and their hydrogenated analogs via [3+2] cycloaddition reactions (microreview)

Jasiński

2023

Chem Heterocycl Comp

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Synthesis of novel isoxazole-containing pyrazolines and pyrazoles via cycloaddition and elimination/aromatization process

Cited by 5 publications

References 25 publications

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

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

Cyclic Deracemization of rac‐Sulfoxides via Alternating Biocatalytic Reduction and Light‐Dependent Oxidation Employing Eosin Y as Photocatalyst

Recent progress in the synthesis of nitroisoxazoles and their hydrogenated analogs via [3+2] cycloaddition reactions (microreview)

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