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Search for "catalyst-free" in Full Text gives 86 result(s) in Beilstein Journal of Organic Chemistry.

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

  • Elena R. Lopat’eva,
  • Igor B. Krylov,
  • Dmitry A. Lapshin and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

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  • that hydrogen bonding is considered as one of the key factors determining the selectivity of catalyst-free sulfoxidations [68]. In such reactions, the selectivity of sulfide oxidation by oxone (sulfoxide/sulfone ratio) was controlled by the solvent nature (deeper oxidation was observed in water than in
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Published 09 Dec 2022

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

  • Pavel A. Topanov,
  • Anna A. Maslivets,
  • Maksim V. Dmitriev,
  • Irina V. Mashevskaya,
  • Yurii V. Shklyaev and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

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  • heterocyclic systems are heteroanalogues of antimicrobial and antibiofilm fungal metabolites. The developed reaction represents the first example of involving 1H-pyrrole-2,3-diones fused at the [e]-side in a [4 + 1] annulation reaction. Keywords: [4 + 1] annulation; catalyst-free; diazooxindole; 1H-pyrrole
  • compounds to molecules containing an enone fragment. Cycloaddition reactions involving diazo and enone moieties are usually carried out using transition-metal catalysis [18][19][20], with catalyst-free reactions being carried out only with the participation of reactive unsubstituted diazomethane [21][22][23
  • ] (Scheme 1). Thus, in the present work, we report a simple, catalyst-free diastereoselective method for the synthesis of dihydrofurans spiro-annulated with an oxindole moiety for the first time. The essence of the method is the use of [e]-fused 1H-pyrrole-2,3-diones (FPDs) as the enone component in a
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Published 10 Nov 2022

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

  • Dharmendra Das,
  • Akhil A. Bhosle,
  • Amrita Chatterjee and
  • Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

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  • catalyst-free halogenation of phenols and anilines via liquid-assisted grinding using PEG-400 as the grinding auxiliary. A series of mono-, di-, and tri-halogenated phenols and anilines was synthesized in good to excellent yields within 10–15 min in a chemoselective manner by controlling the stoichiometry
  • catalyst-free methods, the use of costly and low boiling hexafluoroisopropanol (HFIP) as solvent offered the para-selective halogenation of activated aromatic systems (Scheme 1c) [44]. It is noteworthy to mention that over-halogenation of activated systems like phenols and anilines, due to the high
  • , the optimal reaction conditions for the electrophilic monobromination was set as to grind the substrates (1 mmol) in an automated grinder with 1.1 mmol of NBS at 100 rpm in PEG-400 (0.2 mL per mmol of the substrate) as a grinding auxiliary. We next explored the substrate scope of the catalyst-free
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Published 09 Aug 2022

Menadione: a platform and a target to valuable compounds synthesis

  • Acácio S. de Souza,
  • Ruan Carlos B. Ribeiro,
  • Dora C. S. Costa,
  • Fernanda P. Pauli,
  • David R. Pinho,
  • Matheus G. de Moraes,
  • Fernando de C. da Silva,
  • Luana da S. M. Forezi and
  • Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

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Published 11 Apr 2022

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

  • Yelong Lei and
  • Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

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  • -diazo-3-oxoalkanoates first generate alkoxycarbonylketenes, which undergo an electrophilic ring expansion with aziridines to afford alkyl 2-(oxazolin-2-yl)alkanoates in good to excellent yields under microwave heating. The current method is an activator- and catalyst-free, and clean synthetic strategy
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Published 05 Jan 2022

Direct C(sp3)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

  • Siyu Wang,
  • Lianyou Zheng,
  • Shutao Wang,
  • Shulin Ning,
  • Zhuoqi Zhang and
  • Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

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  • Siyu Wang Lianyou Zheng Shutao Wang Shulin Ning Zhuoqi Zhang Jinbao Xiang The Center for Combinatorial Chemistry and Drug Discovery, School of Pharmaceutical Sciences, Jilin University, 1266 Fujin Road, Changchun, Jilin 130021, P. R. China 10.3762/bjoc.17.167 Abstract A base- and catalyst-free C
  • in the reaction to give the allylation products in 26–91% yields. The developed method provides a straightforward and operational simple strategy for the allylic functionalization of 2-alkypyridine derivatives. Keywords: 2-alkylpyridines; allylic alkylation; aza-Cope rearrangement; catalyst-free
  • our studies on a direct benzylic allylic reaction of 2-alkylpyridines with MBH carbonates as allylic precursors under base- and catalyst-free conditions. As depicted in Scheme 2, we envisioned that the MBH carbonate 2 can undergo the SN2’ reaction with the nucleophilic 2-picoline 1a, giving the
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Published 01 Oct 2021

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

  • Li Liu,
  • Yue Li,
  • Tiao Huang,
  • Dulin Kong and
  • Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

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  • disclosed the application of N-fluorobenzenesulfonimide (NFSI) and NBS (N-bromosuccinimide), respectively, as the halogen sources, with diazoacetamide under catalyst-free conditions via a carbene pathway, which constructed 3-fluorooxindoles and 3-bromooxindoles (Scheme 1, reaction 1) [20][21]. Then, the
  • ) under solvent-free and catalyst-free conditions at room temperature (Table 1, entry 1). To our delight, the desired product 3a was obtained in 19% yield. To further improve the yield, we firstly probed the solvent effect using methanol, THF, toluene, ClCH2CH2Cl, 1,4-dioxane, chloroform, dichloromethane
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Published 07 Sep 2021

An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone)

  • Jochen Löblein,
  • Thomas Lorson,
  • Miriam Komma,
  • Tobias Kielholz,
  • Maike Windbergs,
  • Paul D. Dalton and
  • Robert Luxenhofer

Beilstein J. Org. Chem. 2021, 17, 2095–2101, doi:10.3762/bjoc.17.136

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  • fouling, critically depend mainly on the immediate surface energy. To gain control over the surface chemistry post-processing modifications are generally necessary, since it′s not a feature of additive manufacturing. Here, we report on the use of initiator and catalyst-free photografting and
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Published 19 Aug 2021

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

  • Pezhman Shiri,
  • Ali Mohammad Amani and
  • Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

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  • catalyst-free conditions. A series of azidobenzenesulfonamides 101 was first synthesized from commercially available orthanilic acid by a three-step procedure and then submitted to cycloaddition with different alkynes 102 using CuI and Cu as copper source, tris([1-(tert-butyl)-1H-1,2,3-triazol-4-yl]methyl
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Published 13 Jul 2021

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

  • Shivani Gulati,
  • Stephy Elza John and
  • Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

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  • moderate to good yields under catalyst-free conditions (Scheme 1). A rationale of mechanism proposed the transformation via a Knoevenagel condensation between aldehyde and a molecule of 6 affording A. The concurrent condensation of ammonium acetate with another molecule of 6 led to the formation of an
  • co-workers [50] demonstrated an aqueous phase, diastereoselective, multicomponent reaction involving substituted isatins 35, β-nitrostyrene 36 and benzylamine (20) or α-amino acids 37 using microwave irradiation to afford a library of spirooxindoles 38 in good yields under catalyst-free conditions
  • ). Similarly, the same group extended the work by illustrating [51] a three and four-component microwave-assisted base and catalyst-free reaction for the synthesis of substituted spirooxindoles 40. The three-component reaction involved the reaction between substituted isatin 35, but-2-ynedioates 39 and amino
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Published 19 Apr 2021

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

  • Zhonglie Yang,
  • Yutong Liu,
  • Kun Cao,
  • Xiaobin Zhang,
  • Hezhong Jiang and
  • Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

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  • widespread presence in pharmaceutical-, agrochemical-, and materials sciences [73][74][75]. At present, most of the C–N-bonding reactions require transition-metal catalysis, and the reaction conditions are more stringent; however, the EDA-complex pathway proceeds under mild, catalyst-free conditions
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Published 06 Apr 2021

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

  • Soumyaranjan Pati,
  • Renata G. Almeida,
  • Eufrânio N. da Silva Júnior and
  • Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

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  • the keto-form [53][54][55][56]. Presumably for this reason, the acyclic 1,3-dicarbonyls did not react in the desired way under our experimental conditions. Conclusion In conclusion, we have developed a metal-free and catalyst-free approach for the desulfonylative coupling of N-tosyl-1,2,3-triazoles
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Published 31 Mar 2021

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

  • Maryna O. Mazur,
  • Oleksii S. Zhelavskyi,
  • Eugene M. Zviagin,
  • Svitlana V. Shishkina,
  • Vladimir I. Musatov,
  • Maksim A. Kolosov,
  • Elena H. Shvets,
  • Anna Yu. Andryushchenko and
  • Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

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  • Chemistry, University of Nebraska – Lincoln, 639 N 12th St, Lincoln, NE 68588, USA 10.3762/bjoc.17.57 Abstract A novel catalyst-free synthetic approach to 1,2,3-triazolobenzodiazepinones has been developed and optimized. The Ugi reaction of 2-azidobenzaldehyde, various amines, isocyanides, and acids
  • harder while the microwave-assisted catalyst-free conditions were effective for both terminal and non-terminal alkynes. Keywords: click chemistry; microwave chemistry; multicomponent reactions; triazolobenzodiazepines; Ugi reaction; Introduction Benzannulated heterocycles are among the most important
  • availability of previously described methods for the synthesis of 1,2,3-triazolobenzodiazepines represented in Scheme 1, they have such drawbacks as long reaction time, use of toxic solvents, additional catalysts, etc. In this article, we present a novel tandem Ugi/catalyst-free intramolecular azide–alkyne
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Published 08 Mar 2021

Decarboxylative trifluoromethylthiolation of pyridylacetates

  • Ryouta Kawanishi,
  • Kosuke Nakada and
  • Kazutaka Shibatomi

Beilstein J. Org. Chem. 2021, 17, 229–233, doi:10.3762/bjoc.17.23

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  • lithium pyridylacetates undergo decarboxylative fluorination upon treatment with an electrophilic fluorination reagent to afford fluoromethylpyridines under catalyst-free conditions. Furthermore, we demonstrated the one-pot synthesis of fluoromethylpyridines from methyl pyridylacetates by saponification
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Published 25 Jan 2021

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp3)–H bond functionalization under solvent- and catalyst-free conditions

  • Divya Rohini Yennamaneni,
  • Vasu Amrutham,
  • Krishna Sai Gajula,
  • Rammurthy Banothu,
  • Murali Boosa and
  • Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

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  • malononitrile under catalyst-free conditions have been reported [29]. Wang et al. reported the functionalization of benzylic C–H bonds of 2-methylazaarenes by nucleophilic addition to aromatic aldehydes catalyzed by acetic acid using harmful chlorinated solvent, and this reaction suffers from longer reaction
  • [41][42]. However, to develop advantageous eco-friendly, atom-economical, simple, and efficient synthetic-organic processes under solvent- and catalyst-free conditions in order to synthesize highly demanding pharmaceuticals or natural products can be quite backbreaking [43][44][45]. From this
  • perspective, we herein disclose environmentally benign, atom-economical, catalyst-free nucleophilic additions of benzylic-like azaarene C–H groups to various benzaldehydes under neat conditions (Scheme 3). Results and Discussion With the purpose to develop an environmentally benign process, we first examined
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Published 23 Dec 2020

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

  • Henrik Hupatz,
  • Marius Gaedke,
  • Hendrik V. Schröder,
  • Julia Beerhues,
  • Arto Valkonen,
  • Fabian Klautzsch,
  • Sebastian Müller,
  • Felix Witte,
  • Kari Rissanen,
  • Biprajit Sarkar and
  • Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

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  • the optoelectronic properties of the NDI unit. The binding properties suggest that the combination of the A1·BArF24 axle and NDIC8 is optimal for the synthesis of an NDI-containing [2]rotaxane. We applied Takata’s catalyst-free stoppering approach [58] using the nitrile oxide St for the preparation of
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Published 20 Oct 2020

Et3N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

  • Dharmender Singh,
  • Vipin Kumar and
  • Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

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  • -metal-free strategy is presented to access novel β-carboline-tethered benzothiophenone derivatives from 1(3)-formyl-β-carbolines using elemental sulfur activated by Et3N/DMSO. This expeditious catalyst-free reaction proceeds through the formation of β-carboline-based 2-nitrochalcones followed by an
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Published 20 Jul 2020

Microwave-assisted efficient one-pot synthesis of N2-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

  • Moustafa Sherief Moustafa,
  • Ramadan Ahmed Mekheimer,
  • Saleh Mohammed Al-Mousawi,
  • Mohamed Abd-Elmonem,
  • Hesham El-Zorba,
  • Afaf Mohamed Abdel Hameed,
  • Tahany Mahmoud Mohamed and
  • Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

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  • experimental conditions and the results revealed that performing the reaction in dioxane, CH3CN, THF, or catalyst-free ethanol resulted in no product formation. However, the same products were obtained with lower yields (≈60%) when performing the reaction under conventional heating utilizing pyridine as the
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Published 16 Jul 2020

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

  • Gui-Feng Kang and
  • Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

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  • 100050, China 10.3762/bjoc.16.120 Abstract A catalyst-free one-pot synthetic methodology was developed for the preparation of 1,3,5-triazine-2,4-dithione derivatives through three-component reactions of arylaldehydes, thiourea, and orthoformates. The procedure tolerated a diverse range of arylaldehydes
  • alkylation process [39]. Finally, proton transfer processes afford the desired product 6 and byproduct 5. Conclusion In summary, we have developed a simple and efficient method for the synthesis of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones through a catalyst-free multicomponent reaction
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Published 24 Jun 2020

Architecture and synthesis of P,N-heterocyclic phosphine ligands

  • Wisdom A. Munzeiwa,
  • Bernard Omondi and
  • Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

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  • yields starting from the corresponding N-vinylpyrroles 103 and 104 (Scheme 19). The N-isopropenylpyrrole precursor 104 gave the adducts with 100% regioselectivity. More recently a solvent and catalyst-free method has been reported for vinylpyridines [97]. Preparation of N-heterocyclic phosphines via P–N
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Published 12 Mar 2020

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

  • María C. Mollo,
  • Natalia B. Kilimciler,
  • Juan A. Bisceglia and
  • Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

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  • catalyst free. The scope of the method includes the synthesis of unprecedented examples of 2-alkyl, aralkyl and alkenyl derivatives. Chemical shift data for N-thiobenzoylpiperidine and compound 4a. PPSE promoted ring closure reactions of amido- and thioamido alcohols. Synthesis of compounds 3. Synthesis of
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Published 06 Jan 2020

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

  • Dominika Krištofíková,
  • Juraj Filo,
  • Mária Mečiarová and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

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  • rearrangements. Furthermore, these organocatalysts slowed down the Ireland–Claisen rearrangement in comparison to an uncatalyzed reaction. The catalyst-free reaction proceeded well in green solvents or without any solvent. DFT calculations showed that the activation barriers are higher for reactions involving
  • hand, catalyst-free Ireland–Claisen rearrangements proceed well in green solvents such as CpOMe or under solvent-free conditions. NMR kinetic measurements supported the notion that thiourea and squaramide organocatalysts bind strongly to the starting silyl ketene acetals and prevent the Ireland–Claisen
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Published 10 Dec 2019

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

  • Aleksandr I. Kobelev,
  • Nikita A. Tretyakov,
  • Ekaterina E. Stepanova,
  • Maksim V. Dmitriev,
  • Michael Rubin and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 2864–2871, doi:10.3762/bjoc.15.280

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  • pyrrole-2-one fragment involving the reaction of [e]-fused 1H-pyrrole-2,3-diones with thioureas was developed. The obtained spiro pseudothiohydantoin derivatives were found to undergo a pseudothiohydantoin–thiohydantoin rearrangement. The reactions were shown to proceed under catalyst-free conditions in
  • pseudothiohydantoin–thiohydantoin rearrangement. Therein, the substituents of the thiourea moiety were found to be crucial for tuning the conditions of this rearrangement. Notably, the reactions proceeded under catalyst-free conditions with good yields. Hydantoin-based commercially available drugs. Electrophilic
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Published 27 Nov 2019

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

  • Irina G. Tkachenko,
  • Sergey A. Komykhov,
  • Vladimir I. Musatov,
  • Svitlana V. Shishkina,
  • Viktoriya V. Dyakonenko,
  • Vladimir N. Shvets,
  • Mikhail V. Diachkov,
  • Valentyn A. Chebanov and
  • Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

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  • -mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines. The use of acetoacetic ester derivatives as 1,3-dicarbonyl compounds in the reaction showed high selectivity under catalyst-free conditions, whereas in the case of acetylacetone the formation of a side product was observed. The desired product could be
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Published 08 Oct 2019

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

  • Aleksandr S. Krylov,
  • Artem A. Petrosian,
  • Julia L. Piterskaya,
  • Nataly I. Svintsitskaya and
  • Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

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  • ). Conclusion In conclusion, a series of new 3-methylphosphonylated [1,2,4]triazolo[4,3-a]pyridines, [1,2,4]triazolo[3,4-a]isoquinolines and 1-methylphosphonylated [1,2,4]triazolo[4,3-a]quinolines were synthesized through a catalyst-free 5-exo-dig-type cyclization of chloroethynylphosphonates and commercially
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Published 12 Jul 2019
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