Tandem Catalysis: Synthesis of Nitrogen-Containing Heterocycles

Campos, Joana F.; Berteina‐Raboin, Sabine

doi:10.3390/catal10060631

Cited by 19 publications

(9 citation statements)

References 136 publications

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“…Tandem catalysis is a versatile tool for the synthesis of value-added products starting from inexpensive and readily available starting materials. − Notably, using alcohols as a coupling partner recently, several tandem protocols were developed. ,− In this context, the utilization of methanol as a transfer hydrogenation along with methylating agent is highly desirable.…”

Section: Introductionmentioning

confidence: 99%

(NNC)Ru(II) Complex Catalyzed Selective Functionalization of Ketones with Methanol: Understanding the Role of Ancillary Ligands

Ganguli,

Mandal,

Pradhan

et al. 2023

ACS Catal.

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Employing a single catalyst and substrate, the selective synthesis of all probable products upon varying the reaction conditions is uniquely challenging and exciting to explore. Utilizing methanol, cyclometalated (NNC)Ru(II) complex catalyzed selective transformation of a wide variety of ketones to the corresponding alcohols, β-methylated alcohols, and α-methylated ketones is disclosed. Notably, by changing the reaction parameters, the selective synthesis of all the probable products for the reactions of ketones with methanol was achieved. For these transformations, the role of different ancillary ligands (DMSO, CH 3 CN and PPh 3 ) coordinated to the Ru(II) center was investigated. This protocol was successfully applied for the functionalization of a few pharmaceutically important molecules and to sterically hindered α, α′-disubstituted and α, α′, α′′-trisubstituted ketones. Several control experiments, kinetic studies, Hammett studies, and DFT calculations were carried out to understand this catalytic process.

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Section: Introductionmentioning

confidence: 99%

(NNC)Ru(II) Complex Catalyzed Selective Functionalization of Ketones with Methanol: Understanding the Role of Ancillary Ligands

Ganguli,

Mandal,

Pradhan

et al. 2023

ACS Catal.

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“…These processes provide high atom economy, and diminish the number of time-loosing, cost-demanding, waste-generating operations and purification processes in the chemical synthesis 19 . In the past few years many attentions have been paid to the development and application of multifunctional catalysts by placing different types of active sites on one catalyst for using in tandem catalysis process 20 – 22 . However, the application of multifunctional catalytic systems in the multicomponent TOP starting from alcohols is a new field of studies 23 – 25 .…”

Section: Introductionmentioning

confidence: 99%

A novel base-metal multifunctional catalyst for the synthesis of 2-amino-3-cyano-4H-chromenes by a multicomponent tandem oxidation process

Chahkamali

Sobhani

Sansano

2022

Sci Rep

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A novel base-metal multifunctional nanomagnetic catalyst is prepared by the immobilization of tungstate anions onto γ-Fe2O3 supported with imidazolium moieties. The (γ-Fe2O3-Im-Py)2WO4 was fully characterized using FT-IR, XPS, TEM, FESEM, ICP, TGA, VSM and XRD and used as a multifunctional heterogeneous catalyst for the synthesis of 2-amino-3-cyano-4H-chromenes via a multicomponent tandem oxidation process starting from alcohols under solvent-free conditions. During this process, tungstate catalyzes the oxidation of a wide range of alcohols in the presence of TBHP as a clean source. The in-situ formed aldehydes are condensed with malononitrile and β-dicarbonyl compounds/naphthols/4-hydroxycumarin through promotion by pyridine and imidazolium moieties of the catalyst. By this method, a variety of 2-amino-3-cyano-4H-chromenes are generated in good to high yields from alcohols as inexpensive and easily available starting materials. The catalyst is recovered easily by the aid of an external magnetic field and reused in five successive runs with insignificant decreasing activity.

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“…In the light of this, we successfully employed a mononuclear rearrangement of heterocycles (MHR), also known as the Boulton–Katritzky rearrangement, which allows the conversion of suitably substituted azoles through an intramolecular nucleophilic substitution. This reaction is of synthetic importance since it gives access to nitrogen-containing heterocycles like triazoles used in several fields like medicinal, pharmaceutical, and materials chemistry to name a few. − Furthermore, the MHR has been widely studied from a mechanistic point of view, and depending on the structure of the substrate, it can proceed through basic or acidic catalysis. Being markedly sensitive to solvent effects, it has been widely studied in conventional solvents and also in more complex systems like micelles and cyclodextrins …”

Section: Introductionmentioning

confidence: 99%

Interplay of Acidity and Ionic Liquid Structure on the Outcome of a Heterocyclic Rearrangement Reaction

Marullo

D’Anna

2021

J. Org. Chem.

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The study of suitable probe reactions is a powerful tool to investigate the properties of nonconventional solvents such ionic liquids (ILs). In particular, we studied the acid-catalyzed mononuclear rearrangement of heterocycles (MHR) of the Z-phenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant 1,2,3-triazole, in solution of ILs by means of kinetic measurements. We chose as solvents six ILs differing both in the cation and anion, in the presence of five carboxylic and sulfonic acids as catalysts. For a useful comparison, the reaction was also performed in 1,4-dioxane and methanol. In general, the reaction occurs faster in ILs, compared to conventional solvents, according to the weaker solvation interactions operating in the former media. The effect of IL anion and cation on the reactivity and on the acidic strength of the catalysts was analyzed. To this aim, we measured the acidic strength of the sulfonic acids in each IL, estimated by the equilibrium formation constant of each acid with 4-nitroaniline. We found that the trend of reactivity as a function of the IL anion mainly reflects the larger difference in acidic strengths of the catalyst. Conversely, acidic strength spans a narrower range as a function of the IL cation. As a result, other factors come into play, such as the π–π interactions involving aromatic IL cations, substrate, and transition states, leading to a more articulate trend.

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Tandem Catalysis: Synthesis of Nitrogen-Containing Heterocycles

Cited by 19 publications

References 136 publications

(NNC)Ru(II) Complex Catalyzed Selective Functionalization of Ketones with Methanol: Understanding the Role of Ancillary Ligands

(NNC)Ru(II) Complex Catalyzed Selective Functionalization of Ketones with Methanol: Understanding the Role of Ancillary Ligands

A novel base-metal multifunctional catalyst for the synthesis of 2-amino-3-cyano-4H-chromenes by a multicomponent tandem oxidation process

Interplay of Acidity and Ionic Liquid Structure on the Outcome of a Heterocyclic Rearrangement Reaction

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