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

• advantages. DBDMH is a well-known brominating and oxidizing agent that has recently gained special attention as a highly efficient, commercially available and inexpensive homogeneous catalyst [81]. After optimization, it was found that when employing a molar ratio of benzaldehyde, indole and DBDMH of 1:2

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

• 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

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• closed system. Keywords: aerobic oxidation; benzaldehydes; benzyl alcohols; homogeneous catalyst; honeycomb reactor; Introduction Oxidation plays a key role in synthesizing highly functionalized molecules [1][2]. While Jones oxidation [3] and oxidation using KMnO4 [4] are classical and powerful methods

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

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• isopropanol as reductant, in conjunction with a Noyori–Ikariya ruthenium-based homogeneous catalyst (Scheme 36) [73]. 2 Reactions of difluorocyclopropane and its derivatives Difluorocyclopropanes are synthetically useful substrates for a variety of reactions such as thermal rearrangements, carbocation

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

• acid or a metal on an acid support. Here, we will report all these strategies to perform the one-pot conversion of (ligno)cellulose to isosorbide and the key parameters of this reaction (acidity, nature of the feedstocks, poisoning of the catalyst). Review Combination of an acidic homogeneous catalyst

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

• catalysis are well-known and documented [1][2][3]. However, problems associated with catalyst recovery limit the application of homogeneous catalysts in industry and sometimes make their heterogenization necessary. Unfortunately, the immobilization of a homogeneous catalyst onto supports, such as

• polystyrene, silica, glass, and others [4][5][6][7][8][9][10][11][12] generally leads to a deterioration of the catalytic properties of the initial homogeneous catalyst. This is due to factors including the nonhomogeneous structures of the catalytic centers on the surface of the carrier or inside the

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• reaction was also carried out using [Ru(p-cymene)Cl2]2 as a homogeneous catalyst, but this also did not lead to the formation of the desired product. After establishing the optimum conditions for the reaction, we carried out the alkenylation of several indole derivatives 1 with different acrylates 2 under

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

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• as a homogeneous catalyst for nitrogen reduction under ambient conditions was published, the concentration of the complex in water is very low [25]. Thus, the development of γ-CD–C60 nonwovens by electrospinning might be useful as a novel inhomogeneous solid catalyst containing more C60. In this

Bioinspired cobalt cubanes with tunable redox potentials for photocatalytic water oxidation and CO₂ reduction

• Zhishan Luo,
• Yidong Hou,
• Jinshui Zhang,
• Sibo Wang and
• Xinchen Wang

Beilstein J. Org. Chem. 2018, 14, 2331–2339, doi:10.3762/bjoc.14.208

• dipyridyldiol (LH) as a chelating ligand [47]. Generally, Co4O4-based molecular catalysts can be easily tuned by ligand design, owing to their molecular nature [48][49]. For example, Hill et al. demonstrated that using polytungstate ligands to stabilize “Co4O4” cubane units can produce a robust homogeneous

• catalyst for solar water oxidation [50]. After that, Berlinguette et al. reported that replacing the inorganic ligand with an organic ligand, such as the pentadentate Py5 ligand can also well stabilize the “Co4O4” unit to catalyze water oxidation [51]. This finding is very important, which means there is

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• of the coupled products with unacceptable Pd species led to a hard separation and recycling of homogeneous catalyst systems. In our previous study [4] we reported a ball-milling Heck reaction catalyzed by Pd(OAc)2. Although the catalyst showed the satisfactory reactivity, it was difficult to recover

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• enantioselectivity up to 90%, even after 15 recycles of the catalyst. Jones, Davies and coworkers also recently published a new heterogeneous catalytic cycle base on homogeneous catalyst (S)-23 [72]. The chiral scaffold was covalently supported on silica surface through an organic linker and was tested in a tandem

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

• Krzysztof Skowerski,
• Jacek Białecki,
• Stefan J. Czarnocki,
• Karolina Żukowska and
• Karol Grela

Beilstein J. Org. Chem. 2016, 12, 5–15, doi:10.3762/bjoc.12.2

• immobilisation strategy is to support an unmodified, commercially available homogeneous catalyst on silica gel. This plan was tested by Jacobs et al. [40] and more recently Limbach and co-workers [41], who proved that even the classical Hov-II catalyst can be successfully immobilised on silica gel via

• , such as water, alcohol or CH2Cl2 (Figure 9D and Figure 9E) and possibly deposited on other supports or used as a homogeneous catalyst. As it was noted earlier, we are not considering high recyclability of immobilised complex 8. However, the possibility of removing the deactivated catalyst from the

• literature that ruthenium residues, present in the reaction mixture after olefin metathesis, can serve as an in situ homogeneous catalyst for high pressure hydrogenation of the newly formed C–C double bonds [57][58][59][60][61]. On this basis, we assumed that the ruthenium complex impregnated on carbon 8-C

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• when the reaction temperature decreased to 30 °C and the activity gap between HGIIN+Cl−/SBA-15 on one side and HGIIN+Cl−/MCM-22 and HGIIN+Cl−/MCM-56 on the other side strongly increased (Supporting Information File 1, Figure S4). With HGIIN+Cl− as a homogeneous catalyst no induction period was

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• of the [Cu2(μ-TBTA-κ4N2,N3,N3’,N3’’)2][BF4]2 precatalyst has been solved, the structural characteristics of the active species in solution remain unknown. A homogeneous catalyst for CuAAC reactions in organic solvents was presented by van Koten et al. in 2009 [132]. The (2-aminoarenethiolato)copper(I

A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• effective for the A3-coupling reaction (Table 1, entry 23) and the conversion was comparable to that of the homogeneous catalyst (Table 1, entry 3). We obtained slightly lower conversions when using water or toluene as the solvent (Table 1, entries 14 and 15). Ethanol, acetonitrile, dichloromethane

Continuous proline catalysis via leaching of solid proline

• Suzanne M. Opalka,
• Ashley R. Longstreet and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2011, 7, 1671–1679, doi:10.3762/bjoc.7.197

• homogeneous catalyst can be prepared continuously via reaction with a packed-bed of a catalyst precursor. Specifically, we perform continuous proline catalyzed α-aminoxylations using a packed-bed of L-proline. The system relies on a multistep sequence in which an aldehyde and thiourea additive are passed

• reduction. To our knowledge, this is the first example in which a homogeneous catalyst is produced continuously using a packed-bed. We predict that the method will not only be useful for other L-proline catalyzed reactions, but we also foresee that it could be used to produce other catalytic species in flow

• formation of the active enamine intermediate through breakdown of the putative oxazolidinone intermediate: A substrate-dependent model. Here, we report that a packed-bed of solid proline can be used to create a homogeneous catalyst, and we use this system to perform continuous α-aminoxylations. Not only do

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• reported to afford a series of advantages over the use of solid supports: (a) first of all, no modification of the homogeneous catalyst is required for the immobilization, which is a factor that often affects the efficiency of solid-supported systems; (b) the presence of the counter anion can contribute to

Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

• Hynek Balcar,
• Tushar Shinde,
• Naděžda Žilková and
• Zdeněk Bastl

Beilstein J. Org. Chem. 2011, 7, 22–28, doi:10.3762/bjoc.7.4

• ). Figure 3 shows conversion curves for the RCM of DEDAM in dichloromethane, benzene, and cyclohexane, and the RCM of 1,7-octadiene in cyclohexane. For the RCM of DEDAM, 3 (as a homogeneous catalyst) and 3/SBA-15 were used. The reaction proceeded very rapidly in all solvents used (TOF at 10 min was

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• problems is the ‘heterogenizing’ of a homogeneous catalyst by anchoring the catalyst onto a support. This offers many advantages for industrial application due to their versatile processing capabilities and ease of product/catalyst separation. In view of the potential industrial applications, the

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• enantioselectivity (entry 6). It is interesting to note that, although enantioselectivities were not as high as those obtained with the homogeneous catalyst 1 under batch conditions with the same arylating agents [30], or even with the heterogeneous catalyst 2 used under batch conditions with PhZnEt generated from

• of reagents for the generation of PhZnEt, the observed enantioselectivities were comparable to those recorded with the homogeneous catalyst 1. Thus, further improvement of the present continuous flow system could possibly be achieved with the use of alternative sources of the arylating species [33

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• equilibration during the longer residence times. Incidentally, this silica supported catalyst system was active up to at least three weeks compared to the homogeneous catalyst that was stable up to 20 h only. This property is perhaps a consequence of favourable active site isolation [50]. Several other examples