Construction of multi-substituted pyrazoles <i>via</i> potassium carbonate-mediated [3 + 2] cycloaddition of <i>in situ</i> generated nitrile imines with cinnamic aldehydes

Li, Mei-Mei; Huang, Hui; Tian, Wanrong; Pu, Yiru; Yang, Joey; Ren, Qing; Tao, Fenggang; Ruan, Wenquan; Lü, Jun

doi:10.1039/d2ra00331g

Cited by 9 publications

(12 citation statements)

References 40 publications

(18 reference statements)

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“…ether/EtOAc = 30:1); 1 H NMR (600 MHz, CDCl3) δ 8.00 (s, 1H), 2H),2H),7.46 (dd,J = 8.56,7.33 Hz,2H),10H). 13 C NMR (151 MHz, CDCl3) δ 150. 5, 140.0, 133.2, 132.9, 129.5, 128.7, 128.6, 128.5, 128.4, 127.9, 127.0, 126.7, 126.5, 123.0, 119.0.…”

Section: Template For Synlett Thiemementioning

confidence: 99%

“…Flash column chromatography was performed using flash silica gel (200−300 mesh). 1 H and 13 C NMR spectra were recorded in CDCl3 using a 600 MHz NMR instrument (Bruker Avance Neo).…”

Section: General Informationmentioning

confidence: 99%

“…1 H NMR data are reported as follows: chemical shift, multiplicity (s = singlet; d = doublet; q = quartet; m = multiplet; br = broad), coupling constant (Hz), and integral. Data for 13 C NMR spectra are reported in terms of chemical shift. Accurate mass measurements were performed on an electrospray ionization (ESI) apparatus using time-of-flight (TOF) mass spectrometry.…”

Section: General Informationmentioning

confidence: 99%

“…However, the regioselectivity of the reaction was poor, with each reaction leading to the formation of 1,3,4-trisubstituted along with fully substituted pyrazoles (Scheme 1d). 13 Encouraged by the previous achievements, our group continued our research on the synthesis of substituted pyrazoles. Herein we presented a sequential 1,3-dipole cycloaddition reaction of hydrazonyl chlorides with 3-methyl-4-nitro-5-alkenyl isoxazoles and SnCl2-mediated aromatization/elimination reaction, providing a collection of 1,3,4-triarylpyrazoles in a fully regioselective manner.…”

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confidence: 99%

“…Obtained from hydrazonoyl chloride 1b (50 mg, 0.20 mmol) and isoxazole 2a (56 mg, 0.24 mmol) by procedure B. Yellow oily liquid, yield 37 mg (59%).Rf = 0.65 (Pet. ether/EtOAc = 30:1); 1 H NMR (600 MHz, CDCl3) δ 8.00 (s, 1H), 3H), 7.55 (ddd, J = 8.11, 2.11, 0.91 Hz, 1H), 7.42 (td, J = 8.23, 6.15 Hz, 1H), 7H), 1H), 6.99 (tdd, J = 8.18, 2.45, 0.86 Hz, 1H) 13. C NMR(151 MHz, CDCl3) δ 163.3 (d, J = 246.46 Hz), 150.9, 141.3 (d, J = 10.53 Hz…”

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Sequential 1,3-Dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization: A One-Pot Access to 1,3,4-Triarylpyrazoles

Li¹,

Huang²,

Lü³

2022

Synlett

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A novel one-pot two-step process for the preparation of 1,3,4-triarylpyrazoles was disclosed. This process involved a sequential 1,3-dipole cycloaddition reaction of in situ generated nitrile imines with alkenyl isoxazoles and SnCl2-promoted aromatization/elimination reaction, offering a collection of 1,3,4-triarylpyrazoles in a fully regioselective manner. This protocol featured mild reaction conditions, easily available raw materials and excellent regioselectivity.

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Section: Template For Synlett Thiemementioning

confidence: 99%

“…Flash column chromatography was performed using flash silica gel (200−300 mesh). 1 H and 13 C NMR spectra were recorded in CDCl3 using a 600 MHz NMR instrument (Bruker Avance Neo).…”

Section: General Informationmentioning

confidence: 99%

Section: General Informationmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Sequential 1,3-Dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization: A One-Pot Access to 1,3,4-Triarylpyrazoles

Li¹,

Huang²,

Lü³

2022

Synlett

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Swapping Copper‐Catalytic Process: Selective Access to Pyrazoles and Conjugated Ketimines from Oxime Acetates and Cyclic Sulfamidate Imines

Prakash

Halder

Guin

et al. 2023

Chemistry An Asian Journal

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A powerful CuCl-catalyzed sequential one-pot reaction of aryl methyl ketoxime acetates with cyclic Nsulfonyl imines followed by elimination in the presence of base is reported. This hydrazine-free method conveniently makes CÀ C and NÀ N bonds via a radical cleavage of the NÀ O bond, delivering a special class of C3-hydroxyarylated pyrazoles in good yields. Surprisingly, while employing CuI as a catalyst instead of CuCl, the reaction proceeds through a non-radical pathway which embodies a new tactic for the high-yielding access to value-added conjugated N-unsubstituted ketimines. Moreover, additive-free approach to sulfamidate-fused-pyrazoles was achieved by successfully catalyzing addition and oxidative NÀ N bond-making reactions by CuI and CuCl, respectively. Significantly, our novel technique could convert the prepared ketimines into the pharmacologically recognized 6H-benzo[c]chromene frameworks.

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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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Construction of multi-substituted pyrazoles via potassium carbonate-mediated [3 + 2] cycloaddition of in situ generated nitrile imines with cinnamic aldehydes

Abstract: A highly efficient potassium carbonate-mediated [3 + 2] cycloaddition reaction of hydrazonoyl chlorides with cinnamic aldehydes to furnish multi-substituted pyrazoles under nontoxic and mild conditions has been developed.

Cited by 9 publications

References 40 publications

Sequential 1,3-Dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization: A One-Pot Access to 1,3,4-Triarylpyrazoles

Sequential 1,3-Dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization: A One-Pot Access to 1,3,4-Triarylpyrazoles

Swapping Copper‐Catalytic Process: Selective Access to Pyrazoles and Conjugated Ketimines from Oxime Acetates and Cyclic Sulfamidate Imines

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

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