Selective synthesis of 3-[1-(organylsulfanyl)ethyl]- and 3-[2-(organylsulfanyl)ethyl]-5-chloro-1H-pyrazoles

Samultsev, D. O.; Rudyakova, E. V.; Levkovskaya, G. G.

doi:10.1134/s1070428012100259

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…In this context, pyrazole coordination directs the functionalization of aromatic or aliphatic C–H bonds, but activation of vinylic protons in the electron-rich N -vinyl derivatives has not been yet reported to date. Reactivity studies on vinylpyrazole derivatives are scarce and mainly restricted to Diels–Alder or polymerization reactions …”

Section: Introductionmentioning

confidence: 99%

Rhodium(I)-N-Heterocyclic Carbene Catalyst for Selective Coupling ofN-Vinylpyrazoles with Alkynes via C–H Activation

et al. 2014

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The complex [Rh(μ-Cl)(IPr)(η 2 -coe)] 2 {IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene, coe = cis-cyclooctene} efficiently catalyzes the coupling of alkynes and N-vinylpyrazole via C−H activation, leading to Markovnikovselective butadienylpyrazole derivatives under mild conditions. A straightforward approach to cross-conjugated acyclic trienes is also operative through a one-pot alkyne dimerizationhydrovinylation tandem reaction. The proposed mechanism involves C−H activation of vinylpyrazole directed by nitrogen coordination to the metallic center. Subsequent alkyne coordination, insertion, and reductive elimination steps lead to the coupling products.Several key intermediates participating in the catalytic cycle have been detected and characterized, including a κ-N, η 2 -CC coordinated vinylpyrazole complex and a Rh IIIhydride-alkenyl species resulting from the C−H activation of the vinylpyrazole

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Section: Introductionmentioning

confidence: 99%

Rhodium(I)-N-Heterocyclic Carbene Catalyst for Selective Coupling ofN-Vinylpyrazoles with Alkynes via C–H Activation

et al. 2014

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“…[1][2][3][4][5][6][28][29][30][31][32][33][34][35][36][37][38][39] The chemical transformations of alkenylpyrazoles are still poorly understood. It is known that N-alkenyl-and some 4-alkenylpyrazoles can participate in polymerization, 21,29 complex formation, 30,31 thiylation, 32 and cycloaddition.…”

Section: Introductionmentioning

confidence: 99%

“…[33][34][35] Imidoalkylation of 1-, 3-, 4-, and 5-vinylpyrazoles with N-(2,2,2-trichloroethylidene)ethoxycarbonylamines is also reported 34,36 Chemical transformations of the difficult-to-access 3-alkenylpyrazoles 36-38 and 3-alkenyl-5-chloropyrazoles 28 are even less studied and only very few reactions with oxygen and sulphur nucleophiles have been published. 39,40 We have recently developed methodology for the preparation of hitherto unknown 3-alkenylpyrazoles, 28 possible building blocks for the directed synthesis of substances and materials for advanced technologies, from the corresponding 3-haloalkyl pyrazoles. The aim of the present work is to study of chemical behavior of 3-alkenylpyrazoles in the reactions with aromatic and aliphatic thiols.…”

Section: Introductionmentioning

confidence: 99%

Novel directed synthesis of functionalized pyrazole derivatives via regioselective solvent-free thiylation of 3-alkenylpyrazoles with arenethiols

Levkovskaya¹,

Rudyakova²,

Kobelevskaya³

et al. 2016

Arkivoc

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Unprecedented easy (3 min., room temperature) regioselective addition of thiols to the endocyclic double bond of 3-vinyl-, prop-1-enyl-and isopropenyl, including those with bulky substituents in the position 1 of the pyrazole ring, has been found for the reaction of arenethioles with 3-alkenyl-5-chloropyrazoles. The reaction proceeds under solvent-free and catalyst-free conditions to afford 3-[(2-arylsulfanyl)alkyl]-5-chloropyrazoles in excellent yields. High rate of the process is likely due to protonation of the "pyridine" nitrogen atom of the pyrazole ring to give a pyrazolium ion which activates the vinyl group towards nucleophilic attack by the simultaneously formed arylthiolate anions.

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“…We succeeded to extend this procedure to the preparation in the 33% yield of 3-(1-bromoethyl)-1-methyl-1H-pyrazole (IV), an important precursor in the synthesis of 3-alkenylpyrazole [29] and functionalized derivatives of 3-alkylpyrazole [35] (Scheme 2). In continuation of the research in the chosen direction we synthesized NH-unsubstituted pyrazoles Va-Vc and explored their alkylation with various alkyl bromides and methyl iodide.…”

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confidence: 99%

Ratio of 1,3- and 1,5-dialkyl-substituted pyrazoles obtained from chlorovinyl alkyl ketones and alkylhydrazines, 3(5)-pyrazoles and alkyl bromides

et al. 2014

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Unsymmetrically substituted 1,3-and 1,5-dialkylpyrazoles and 1,3-dialkyl-5-chloropyrazoles were prepared. 2-Chlorovinyl ketones react with С 1 -С 8 -alkylhydrazines along two routes giving mixtures of 1-R'-3-R-and 1-R'-5-R-pyrazoles with the prevalence of 1,3-isomer. The proportion of 3-substituted 1-alkylpyrazole in the isomers mixture grows from 60 to 94-97% with growing length of the alkyl chain in the hydrazine. The alkylation of 1-unsubstituted 3(5)-alkylpyrazoles with alkyl bromides afforded predominantly (by 16-50%) 1,3-disubstituted pyrazoles. 1,3-Dialkyl-5-chloropyrazoles form from 2,2-dichlorovinyl alkyl ketones and functionalized alkylhydrazines. It was suggested to synthesize 1,3-dialkyl-substituted pyrazoles by dechlorination of unsymmetrically substituted 1,3-dialkyl-5-chloropyrazoles in the presence of complex nickel catalyst and water as the proton source.

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Selective synthesis of 3-[1-(organylsulfanyl)ethyl]- and 3-[2-(organylsulfanyl)ethyl]-5-chloro-1H-pyrazoles

Cited by 10 publications

References 4 publications

Rhodium(I)-N-Heterocyclic Carbene Catalyst for Selective Coupling ofN-Vinylpyrazoles with Alkynes via C–H Activation

Rhodium(I)-N-Heterocyclic Carbene Catalyst for Selective Coupling ofN-Vinylpyrazoles with Alkynes via C–H Activation

Novel directed synthesis of functionalized pyrazole derivatives via regioselective solvent-free thiylation of 3-alkenylpyrazoles with arenethiols

Ratio of 1,3- and 1,5-dialkyl-substituted pyrazoles obtained from chlorovinyl alkyl ketones and alkylhydrazines, 3(5)-pyrazoles and alkyl bromides

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