Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• pyrroles/indoles 4/9 allowing access to 2,3-dihydroisoxazoles 77/78 bearing an all-substituted stereocenter at the C3 position. A dual catalytic activity of the Brønsted acid catalyst was illustrated by the authors which was initiated with a smooth protonation of the OH group in 76 with a subsequnte

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

• magnetically recoverable by simple magnetic decantation. In addition, the catalytic activity of the catalyst remains unaltered after six consecutive cycles (Figure 3). Using this catalyst, various nitrogen-substituted pyrrole derivatives 31 were synthesized in 55–96% yields through the reaction between various

• effect on product yield and no loss of catalytic activity. Moreover, a plausible mechanism for the constructions of N-arylpyrroles is shown in Scheme 17b. In the first step, the acetal group of 2,5-DMTHF (2) is protonated by β-CD-SO3H to produce intermediate A. Intermediate A is nucleophilically attacked

• of the catalyst for up to nine consecutive runs without loss of catalytic activity. Recently, Rohit et al. [86] described a modified Clauson–Kaas synthesis of N-substituted pyrrole with up to 89% yields by microwave irradiation at 120 °C in neat conditions by reacting amines 66 with 2,5-DMTHF (2) in

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• 1,4-dioxane the transformations performed the best (Table 1, entries 3–5). A series of copper catalysts such as CuI, CuCN, and Cu2O was screened, in which some showed good catalytic activity (Table 1, entries 6–9), and Cu2O was identified as the most effective catalyst for the desired transformation

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• also found to have a higher catalytic activity for the ortho-alkylation of pyridines with styrenes to give the linear alkylated products (5b,c, Scheme 2). Further, the authors proposed that the C–H bond activation could be the rate limiting step based on kinetic isotope experiments (KIE). The proposed

• which resulted in C3-alkylated pyridines 51. Based on the reactions performed for the catalytic activity of the silyl-iridium complex, the authors proposed a catalytic mechanism (Scheme 11b). The mechanism involves the initial formation of the active silyl-iridium catalyst A which through oxidative

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• ) with its counterpart from the liquid state transmetallation route (5ls) in catalysis. We found that 5bm was catalytically active, however displaying slightly diminished activity in general most likely due to different adduct ratio inhibiting the catalytic activity (Scheme 3). This was established using

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• porphyrins used in the Cu(I)-catalyzed click reaction have been metalated prior to the reaction; otherwise, Cu metal can be inserted into the porphyrin cavity. As a result, the catalytic activity of Cu will decrease, it will be more difficult to remove, and more additional steps will be required to

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• the ionic liquid, catalytic activity is suppressed and product formation is not observed at all (Table 4, entry 5). An additional advantage of ILs is the reusability of the catalytic system, we were able to reuse our system for three consecutive runs. Conclusion In conclusion, we have established a

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

• organic chemistry. It allows chemists to avoid the use of precious and (or) toxic metals by taking advantage of the catalytic activity of small and synthetically available molecules. Today, the term organocatalysis is mainly associated with redox-neutral asymmetric catalysis of C–C bond-forming processes

• different chemoselectivity: secondary and benzyl alcohols are more easily oxidized. The great diversity of catalytic systems based on amine-N-oxyl radicals for alcohol oxidation was proposed [74][76][77][95]. Amine-N-oxyl organocatalysts with enhanced catalytic activity were developed by the modification of

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• advantages of heteroleptic over homoleptic cages and they showed examples of nanomechanical motion influencing catalytic activity. They also discuss the regulation of the catalytic activity of heteroleptic systems by an external stimulus. We are very grateful to all colleagues who contributed to this issue

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• HKR of epichlorohydrin with water was selected as a classical model to evaluate the catalytic activity of Co-unsymmetrical salen complexes 2e, 2f, and 2g for the asymmetric ring opening of epoxides. Enantiomeric excess (ee) results of 3-chloro-1,2-propanediol from the HKR reactions were summarized in

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

• achieved at lower electromagnetic fields and higher flow rates (Q = 152 NL/h) [34]. Not only was less carbon formation observed with this new material, but also little to no reduction in catalytic activity. Although this is not yet the most efficient process that could be used on a large scale, it is a

• ruthenium increased the catalytic activity and allowed the catalytic process to be carried out at lower reaction temperatures, which was explained by the fact that the surface temperature of the nanoparticles was in fact significantly higher than 200 °C. It was also not necessary to implement an additional

• is important not only in the context of energy storage, CO2 reduction, and climate change prevention, but also because they provide a country-independent source of energy. However, for use in a continuous flow system, the catalyst must have extremely high SAR and catalytic activity. Recently, a

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

• -worker have demonstrated the design and synthesis of urea-functionalized 2D/3D architectures and their catalytic activity. The urea moieties were incorporated within the building blocks and were meant to serve as binding sites for appropriate substrates, therefore, promoting selectivity and reactivity

• + 26), respectively, were successfully employed as visible-light photocatalysts for a cross-coupling cyclization of N,N-dimethylaniline (27) and N-alkyl/aryl maleimides 28 (Figure 6). Notably, the systems showed much higher catalytic activity compared to similar reactions with the dye or cages alone

• trans-styrylboronic acid (43, Figure 10). The catalytic reaction inside the chiral cavity of (S)-40 provided a yield up to 91% with a very high enantioselectivity (94% ee). In contrast, the larger chiral macrocycle (S)-41 afforded a slightly lower catalytic activity (87%), however, at a similar

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• linezolid (1) and rivaroxaban (2). The main aim of this study was the evaluation of the catalytic activity and enantioselectivity of several established enantioselective catalysts applicable to the asymmetric Henry reaction, which were used for the preparation of chiral intermediates of these drugs. Various

• corresponding nitroaldol 22 by the action of the complex Cu(OAc)2/Ia with practically identical de of 88%. On the other hand, the interpretation of chemical yields is rather indistinct. Generally, the copper(II) complexes of ligands Ia and IV exhibited a higher catalytic activity than the catalysts derived from

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

• catalytic activity of selenium mesoporous molecular sieves (SeMCM-41) in the oxidation of 16 (Table 1, entry 10). The approach was performed using H2O2 as oxidant in acetic acid over SeMCM-41 (Si/Se = 30) at 100 °C [56]. In this case, a conversion of 99% was achieved and menadione (10) was obtained with 68

• catalyst for the oxidation of 2-methylnaphthalene (16) with H2O2 [59]. The complex L1-Fe(III) (L1 = (2-((2-(2-((2-((2-hydroxyphenylimino)methyl)phenoxy)methyl)benzyloxy)benzylidene)amino)phenol) showed the best catalytic activity with 58.54% selectivity and 79.11% conversion (Table 1, entry 13) [59

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• promoting the protonation of the substrates leading to the formation of cationic intermediates that are stabilized within the cavity with consequent peculiar features in terms of acceleration and product selectivity. In all cases the catalytic activity displayed by the hexameric capsule is remarkable if

• performed extra control experiments for each investigated reaction also only with the more symmetrical and less acidic capsule A to underline the effect of the water content on the catalytic activity. (S)-Citronellal isomerization to cyclic secondary alcohols (S)-Citronellal is an enantiopure monoterpenoid

• neoisopulegol ratio (Table 1, entry 2). The reaction with 16 occupied by 3 as a competitive guest led to a marked decrease of catalytic activity, and negligible conversion was observed using 4-n-hexylresorcinol (2) as a molecule with similar H-boding properties compared to 1 (Figure 1D and E; Table 1, entries 3

A Se···O bonding catalysis approach to the synthesis of calix[4]pyrroles

• Qingzhe Tong,
• Zhiguo Zhao and
• Yao Wang

Beilstein J. Org. Chem. 2022, 18, 325–330, doi:10.3762/bjoc.18.36

• ]pyrrole derivatives. The Se···O bonding interactions between selenide catalysts and ketones gave rise to the catalytic activity in the condensation reactions between pyrrole and ketones, leading to the generation of calix[4]pyrrole derivatives in moderate to high yields. This chalcogen bonding catalysis

• phosphonium selenide catalysts which showed catalytic activity in assembly reactions [41], Michael addition reactions [41], Rauhut–Currier reactions [42], cyanosilylation reactions [43], and cycloaddition of vinylindoles through chalcogen–π bonding catalysis [44]. Our previous works demonstrated that Se···O

• monodentate and bidentate catalysts could activate ketones. Accordingly, either a single activation or a double activation mode could be an effective driving force to promote this transformation, albeit with distinct catalytic activity. Conclusion In summary, we developed a Se···O bonding catalysis approach

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• the bench stability of the nanoparticles, and hence methylmagnesium bromide was introduced to retain the catalytic activity. Heterogeneous green protocols Rizi and co-workers reported a silica-supported green heterogeneous Fe(III) catalyst for the cross-coupling reaction of aryl iodides and

• product of reductive elimination regenerates the catalyst. Javidi and co-workers reported a sequence of magnetically separable catalysts which consisted of Schiff base complexes of metal ions supported on superparamagnetic Fe3O4 nanoparticles (Scheme 16) [32]. To examine their catalytic activity, a

• supported catalyst could be easily separated by an external magnetic field due to its paramagnetic nature, and it could be reused and recovered without loss of catalytic activity. The desired alkyne products were obtained in high yields. One of the most attractive features of this strategy was the finding

Diametric calix[6]arene-based phosphine gold(I) cavitands

• Gabriele Giovanardi,
• Andrea Secchi,
• Arturo Arduini and
• Gianpiero Cera

Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21

• , calix[4]- [9][10][11][12][13] and resorcin[4]arene [14][15][16][17] are the most exploited cavitands due to their inherent limited flexibility and already proved their ability to control the catalytic activity of late-transition metals and particularly gold(I) catalysts [18][19][20][21][22][23][24][25

• catalytic activity was demonstrated in promoting gold(I)-catalyzed cycloisomerization of 1,6-enynes, with ample scope and high regioselectivity. However, preliminary studies suggested that the catalytic event occurs outside the macrocyclic cavity. In order to get more insights on the role of the cavity to

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• (NPs) and therefore automatically increases the dispersibility of the catalyst throughout the medium, resulting in a higher catalytic activity [23]. 1,4-DHPs are considered one of the most useful molecular scaffolds in medicinal chemistry. The scaffold is the main constituent of several crucial drugs

• up to 97% using an external magnet. In a series of five reactions, the catalyst was used repeatedly without significant decrease in catalytic activity (Figure 7). The slight reduction of the yield in later reactions may have been a result of the loss of catalyst in the recycling process. Comparison

• to five consecutive reactions without significant reduction of catalytic activity. To the best of our knowledge, no previous work is known using a Ni–chitosan nanocatalyst for the synthesis of C5–C6-unsubstituted 1,4-DHPs. Experimental Materials and instrumentation All starting materials were

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• . It was concluded that the catalytic activity of the MDO was the result of the cooperative action of both constituents. Several examples of such MDOs are included in the paper. The reported yield varies from 56–90% with excellent ee ≈ 99% in all cases. 1.2. Reactions catalyzed by chiral squaramide

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• are otherwise highly conserved. Site-directed mutagenesis experiments for these residues are reported that showed different effects, resulting in some cases in an improved catalytic activity, but in other cases in a loss of enzyme function. For other enzyme variants a functional switch was observed

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• -metathesis (ROCM) have found high utility in the creation of C=C bonds and in the synthesis of a number of organic molecules, functionalized scaffolds or various building blocks. The efficient catalytic activity and remarkable functional group tolerance of commercially available versatile Ru-based olefin

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• highlight that solvent-free conditions are particularly effective and allow for reducing the catalyst loading by the factor of 10, thereby obtaining a higher share of 3dia and full conversion towards 3dic. Interestingly, the catalytic activity of TPP in reactions with 3 as the Michael acceptor is only

• for reacting weak Michael acceptors and/or less acidic alcohols. Phosphine loadings of only 1 mol % with respect to the Michael acceptor are in many cases sufficient to provide a full conversion within 24 h at room temperature. With good Michael acceptors and/or acidic alcohols the catalytic activity

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• pores is responsible for the main catalytic activity, such as in carbonaceous materials [47][48]. When a network with full functionality cannot be formed easily, one can form a rigid neutral host and modify the pores subsequently. Herein, the nanoporous system is magnified to macropores in hydrogel