Hydrogenation

Török, Béla; Schäfer, Christian; Kokel, Anne

doi:10.1016/b978-0-12-817825-6.00003-3

Cited by 7 publications

(6 citation statements)

References 386 publications

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“…The data described in Table 1 clearly shows that the reaction occurs effectively with fuming HNO 3 , and that the hydrocarbon/acid ratio significantly affects the product yield and distribution. A notable observation is that the presence of a catalyst or co-acid, in the form of K-10 montmorillonite, a well-known solid acid ( Dasgupta and Török, 2008 ; Török et al, 2021b ), significantly activates the system and over-nitration occurs in a considerable extent. If high acid ratio and K-10 are combined, nearly 60% of the product is an over-nitrated compound ( Table 1 , entry 4).…”

Section: Resultsmentioning

confidence: 99%

Chemo-and regioselective aqueous phase, co-acid free nitration of aromatics using traditional and nontraditional activation methods

Plasse,

Mooney,

Mastyugin

et al. 2024

Front. Chem.

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Electrophilic aromatic nitrations are used for the preparation of a variety of synthetic products including dyes, agrochemicals, high energy materials, fine chemicals and pharmaceuticals. Traditional nitration methods use highly acidic and corrosive mixed acid systems which present a number of drawbacks. Aside from being hazardous and waste-producing, these methods also often result in poor yields, mostly due to low regioselectivity, and limited functional group tolerance. As a consequence, there is a need for effective and environmentally benign methods for electrophilic aromatic nitrations. In this work, the major aim was to develop reaction protocols that are more environmentally benign while also considering safety issues. The reactions were carried out in dilute aqueous nitric acid, and a broad range of experimental variables, such as acid concentration, temperature, time, and activation method, were investigated. Mesitylene and m-xylene were used as test substrates for the optimization. While the optimized reactions generally occurred at room temperature without any activation under additional solvent-free conditions, slight adjustments in acid concentration, stoichiometric equivalents, and volume were necessary for certain substrates, in addition to the activation. The substrate scope of the process was also investigated using both activated and deactivated aromatics. The concentration of the acid was lowered when possible to improve upon the safety of the process and avoid over-nitration. With some substrates we compared traditional and nontraditional activation methods such as ultrasonic irradiation, microwave and high pressure, respectively, to achieve satisfactory yields and improve upon the greenness of the reaction while maintaining short reaction times.

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Section: Resultsmentioning

confidence: 99%

Chemo-and regioselective aqueous phase, co-acid free nitration of aromatics using traditional and nontraditional activation methods

Plasse,

Mooney,

Mastyugin

et al. 2024

Front. Chem.

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“…This approach is essential for simplifying the synthetic process to efficiently produce new and known structures of heterocyclic compounds for biological applications and material science. 1 2 3 The combination of MCRs with ultrasound or microwave techniques has allowed for the exploration of less reactive substrates to obtain bioactive compounds such as chromenes. 4–6…”

Section: Table 1 Optimization Studies Under Conventiona...mentioning

confidence: 99%

Ultrasound-Assisted, BF3·OEt2-Promoted, Multicomponent Synthesis of Chromene-Based Podophyllotoxin Analogues

Laurentiz,

Santos

2024

Synlett

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A novel method was developed to synthesise chromene-lactone analogues of podophyllotoxin using an ultrasound-assisted multicomponent reaction (MCR). The MCR involved tetronic acid, phenols, and aromatic aldehydes and was promoted by BF3·OEt2, resulting in the production of ten derivatives with different substituents on the aromatic rings in yields ranging from 32% to 93%. These compounds are of interest due to their reported activity against tumour cells. Their ease of synthesis through the MCR may allow for more in-depth studies on anticancer activity, as well as investigations of other biological targets. The synthesised derivatives contain important pharmacophoric groups for potential applications in medicinal chemistry.

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“…Gold has gained significant attention as a catalytic material [ 141 ]. A gold catalyst has been applied in a modified Friedländer synthesis [ 142 ] of quinolines, to make the old protocol comply with current safety and environmental standards. The Au (III)-based catalyst promoted the condensation/annulation pathway under mild conditions using 2-amino acetophenones and 1,3-dicarbonyl compounds ( Scheme 16 a) [ 143 ].…”

Section: One-nitrogen-containing Condensed Heterocyclesmentioning

confidence: 99%

Green Synthesis of Aromatic Nitrogen-Containing Heterocycles by Catalytic and Non-Traditional Activation Methods

2023

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Recent advances in the environmentally benign synthesis of aromatic N-heterocycles are reviewed, focusing primarily on the application of catalytic methods and non-traditional activation. This account features two main parts: the preparation of single ring N-heterocycles, and their condensed analogs. Both groups include compounds with one, two and more N-atoms. Due to the large number of protocols, this account focuses on providing representative examples to feature the available methods.

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Hydrogenation

Cited by 7 publications

References 386 publications

Chemo-and regioselective aqueous phase, co-acid free nitration of aromatics using traditional and nontraditional activation methods

Chemo-and regioselective aqueous phase, co-acid free nitration of aromatics using traditional and nontraditional activation methods

Ultrasound-Assisted, BF3·OEt2-Promoted, Multicomponent Synthesis of Chromene-Based Podophyllotoxin Analogues

Green Synthesis of Aromatic Nitrogen-Containing Heterocycles by Catalytic and Non-Traditional Activation Methods

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