Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• of Fe3O4 nanoparticles (Scheme 15) [101][102]. This organic–inorganic hybrid material was synthesized by the immobilization of the dodecatungstovanadophosphoric acid (HPA) on TPI-Fe3O4 with N-[3-(triethoxysilyl)propyl]isonicotinamide (TPI), acting as the linker for the heterogeneous catalyst, while

• introduced nano n-propylsulfonated γ-Fe2O3 (NPS-γ-Fe2O3), which constitutes a magnetically recyclable heterogeneous catalyst that works in the exact same manner as HPA/TPI-Fe3O4 [103]. Some small differences between the two methods were the ability of ketones to form the respective BIMs, when NPS-γ-Fe2O3 was

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• having a triisopropoxy(propyl)silyl ((-CH2)3Si(OiPr)3) substituent on the imidazole ring through in situ transmetallation. One of these complexes, 78a, was successfully anchored on mesoporous silica MCM-41 to afford a new heterogeneous catalyst (Scheme 27). Both compounds were subsequently used as

• . Unexpectedly, no reaction occurred when complex 78 anchored on mesoporous silica 78a-MCM-41 was used as heterogeneous catalyst. 2.2 Conjugate addition The conjugate addition is a reaction in which a nucleophile attacks at the β-position of an activated C=C moiety to give an addition product (Scheme 39). As

• benzyl azide with phenylacetylene (Scheme 52) [39]. In contrast to the hydrosilylation reaction (see section 2.1), both complexes catalyzed the cycloaddition reaction; however, the heterogeneous catalyst was found to be less active than the homogeneous catalyst. Straub and co-workers [70] in 2016 instead

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• , Hosseini-Sarvari and co-workers [72] described a new and greener Clauson–Kaas method for the synthesis of N-substituted pyrroles 41 in 80–98 % yields by condensing 2,5-DMTHF (2) with amines 40 in the presence of the novel heterogeneous catalyst nano-sulfated TiO2 under solvent-free conditions (Scheme 19

• ] used the heterogeneous catalyst H3PW12O40/SiO2 for the Clauson–Kaas synthesis of N-substituted pyrrole derivatives 63 (Scheme 30) by the reaction of amines 62 with 2,5-dimethoxytetrahydrofuran (2) in petroleum ether at reflux conditions in 60–93% yields (method 1) and MW-assisted solvent-free

• 2.5 mol % HPA/SiO2 as catalyst, solventless under MW irradiation. The main advantages of this protocol is its greener, eco-friendly, stable and reusable heterogeneous catalyst, smooth and selective reaction under solvent-free conditions, excellent yields of products, easy work-up and simple handling

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• 1,3-dicarbonyl compounds using a catalytic amount of hydrazine hydrate without solvent in a short reaction time (10 min) [14]. Reactions of 2-aminothiophenols with β-keto esters and β-diketones under microwave irradiation (MWI) using basic alumina as heterogeneous catalyst without solvent afforded 4H

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• and scalable reaction conditions. Here, we report a continuous-flow approach to metallaphotoredox catalysis using a heterogeneous catalyst that combines the function of a photo- and a nickel catalyst in a single material. The catalyst is embedded in a packed-bed reactor to combine reaction and

• processes [5] (Figure 1d): The heterogeneous catalyst remains located in a specific part of the reactor through which the reaction mixture is pumped, which reduces material damage through attrition and the confinement of the catalysts in the packed bed lifts the need for solid separation. If the catalyst is

• (12 h, in agreement with previous observations, see Figure 4a), only a minor decrease in the catalyst activity (about 1% per day) was observed throughout the experiment, demonstrating the good long-term stability of the heterogeneous catalyst. In particular, the catalyst turnover number (TON

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• consists of a membrane called a membrane electrode assembly (MEA), which can act as supporting electrolyte, electrode, and heterogeneous catalyst. Therefore, the further addition of a supporting electrolyte is not necessary for the electrochemical reactions using a PEM reactor, which offers clean and

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• second variant is the steam methane reforming process. Since complex solids such as wood, sewage sludge or municipal waste cannot be evaporated, they are reformed using supercritical water on a heterogeneous catalyst at 250–300 bar, 400–550 °C, and a large excess of water [28]. The former process is the

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• of the guest molecule was proven by UV–vis and IR spectroscopy. The multicomponent prism (Figure 3) was finally utilized as a heterogeneous catalyst for Michael and Diels–Alder (DA) reactions in water, representing an uncommon hydrogen-bond donating heterogeneous catalyst [59]. Intrigued by the

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• –hexane mixtures. Yields in toluene or xylene were typically around 90% (Table 1, entries 25 and 26). Although most reported microwave-promoted organic reactions on solid supports are performed without additional solvent [46][47], the combination of a nonpolar solvent with a polar heterogeneous catalyst

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

• aryl iodides containing electron-donating and electron-withdrawing groups exhibited good to excellent results in the reaction. Notably, the yield of the Click reaction with 2-iodotoluene decreased due to the steric effects. Moreover, the utilization of an efficient heterogeneous catalyst and

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• . In 2008, the group of Sartori developed a flow setup for nitroaldol condensations of different benzaldehydes exploiting a silica-supported amine (KG-60-NH2) as a heterogeneous catalyst (Scheme 21) [133]. Secondary and tertiary amine-supported catalysts were also investigated, although they were found

• coated multichannel microreactor with an integrated zeolite ZSM-5 membrane (Scheme 28) [156][157]. The heterogeneous catalyst used was a Cs-exchanged faujasite NaX. The membrane maximised the outcomes in comparison to tested fixed-bed and microreactors. The ZSM-5 membrane allowed fast water exclusion

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• and with a very small amount of the catalyst needed (Table 28). The heterogeneous catalyst PdL10b system worked significantly better than the conventional homogeneous synthesis, even when using a significantly higher amount of the PdL10a catalytic species in the homogeneous system. The results were

• excellent both in terms of enantioselectivities and conversions (up to 98%; up to 83% ee; Table 28). The reuse of the heterogeneous catalyst has not been studied in this case. In 2020, our group reported the first heterogeneous polystyrene-supported recyclable catalyst for the asymmetric conjugate additions

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

• and selective heating of the heterogeneous catalyst [20][21][22][23]. Even though the MWA technology is advantageous, a major challenge posed is the scale-up at the industry level where protocol efficiency at kilogram scale is mandatory. With rapid heat generation, and litres of solvents often safety

• reusability of the heterogeneous catalyst is also an advantage of the stated strategy. The higher yields >82% obtained from the microwave-assisted protocol reveal its competency over the conventional method (79%) along with the time parameter wherein the time was reduced from hours to just minutes (6 h to 20

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• ; heterogeneous catalyst; immobilized copper catalyst; lignosulfonate; nitrogen-containing heterocycles; solid acid; Introduction Heterogeneous metal catalysts have been continuously receiving considerable attention in the field of organic synthesis owing to the advantages of easy separation and recycling [1][2

• -Cu-promoted conditions as well, and gave the product 4o in 65% yield. The successful attempts in the three-component reaction of 4-aminoindoles (1a), alkynes and aldehydes indicate that the heterogeneous catalyst LS-FAS-Cu is competent for catalyzing nitrogen-containing heterocyclic compounds without

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada 10.3762/bjoc.16.201 Abstract In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• . Conclusion An environmentally benign NDL catalyst was characterized and utilized as a heterogeneous catalyst for the synthesis of 2-aryl-1-arylmethyl-1H-benzo[d]imidazoles, dihydropyrimidinones/ -thiones, and 2-amino-4-(hetero)aryl-3,5-dicarbonitrile-6-sulfanylpyridines in a mixture of ethanol and H2O 1:1

One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

• to isosorbide, a sustainable and interesting route should be the design of a heterogeneous catalyst composed of a metal supported on an acid support. These catalysts should be designed in order to be stable in water and tolerant to the presence of lignin. Otherwise, the solution should be to realize

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• separation and recycling, HPCats show advantages such as an enhanced photostability and selectivity [47][48]. A heterogeneous catalyst with a high surface area is often associated with a greater number of surface-active sites for catalysis to occur and makes morphological control critical to the catalyst

• chemistry as previously discussed. This combines the ease of separation and recyclability of a heterogeneous catalyst, with the detailed characterisation, accessibility and synthetic versatility of a homogeneous photocatalyst. Some desirable properties of a solid support are hence; (i) a strong

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• , including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate

• , providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled. Keywords: Brønsted acid catalyst; charge-assisted hydrogen-bonded framework; Diels–Alder; epoxide ring opening; heterogeneous catalyst; Introduction Tremendous successes in homogeneous

• . Depending on the polarity of the solvent mixture, F-1 could function as a purely heterogeneous catalyst or as a reservoir, providing some soluble F-1 as the real catalyst. In all cases the catalyst could easily be recovered and recycled. The system has the potential for future elaboration, for example, by

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• (40) with pyridine-3,5-dicarboxylic acid (39) using P(OC₆H₅)₃ (TPP). The ligand 41 was immobilized on 3-chloropropyltrimethoxysilane (CPTMS, 43) to afford TMSP–nSiO2 (44). Material 44 was then reacted with CuBr2 in methanol at reflux for 24 h to produce the heterogeneous catalyst Cu(II)Br2–BTP@TMSP

• ) (64) (Scheme 10) [32]. An interesting aspect of the heterogeneous catalyst SNIL–Cu(II) (64) is its successful application in the [3 + 2] cyclization synthesis of “click” products under mild reaction conditions. 0.05 mol % of 64 and 2 mol % of sodium ʟ-ascorbate were used to prepare a range of

• substitutions were efficiently transformed to the corresponding products in excellent yields. To show the high efficiency of this catalytic system, bis-“click” and tris-“click” reactions were also effectively performed (Scheme 10). The heterogeneous catalyst 64 could be used for six consecutive cycles without

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• -one (4), arylglyoxals 5, and acetamide (6) using SnCl2–SiO2 nanoparticles as heterogeneous catalyst under solvent-free conditions [10]. However, as we found out, the use of a catalyst was unnecessary for this transformation. In turn, refluxing the reaction mixture in acetonitrile was sufficient for

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• electrodes Electrodes with chiral surfaces have long been prepared through the adsorption of chiral active auxiliaries onto the surface of the metallic electrode. In such cases, the chiral electrode becomes an inherent part of the electrochemical cell and serves as a heterogeneous catalyst. A recent article

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• the first step which was converted to the final product via radical cation intermediate 17 in the second step (Scheme 6). This additive-free approach offered an easy separation and reusability of heterogeneous catalyst along with the use of air as environmentally benign oxidant. The use of zinc and

• the use of toxic reagents and solvents, harsh reaction conditions and long reaction times. The use of a heterogeneous catalyst and water made this method a green and sustainable approach for organic transformations. This transformation involved the well known three-component reaction of 3 with 1 and 2

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• multicomponent reactions and some of them were mentioned below. Moosavi-Zare et al. immobilized 1,4-diazabicyclo[2.2.2] octanesulfonic acid chloride on SiO2 as a nanostructured heterogeneous catalyst. The silica-bonded 1,4-diazabicyclo[2.2.2]octanesulfonic acid chloride catalyst 71 was prepared in some steps as

• 80 °C using MWCNTs-SO3H composite 97 as the efficient and heterogeneous catalyst. The reaction was also performed under the same conditions using different catalysts including Fe3O4, CuFe2O4, ZnS nanoparticles, TiO2, MWCNTs, MWCNTs/H2SO4, MWCNTs–COOH, and Ph–SO3H, but the products were not achieved