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

• -proline-modified magnetic nanoparticles (LPMNPs) that combine organocatalytic protocols with nanocatalysis, which enhances the surface-to-volume ratio of the catalyst opening up new possibilities [107]. The ʟ-proline molecules were anchored on a Fe3O4@SiO2 nanoparticle, which was already known for its

• -proline on the surface of the magnetic nanoparticle via iminium formation as seen in Scheme 18, allowing the indole to attack the formed double bond and initiate the Michael-type mechanism [107]. In an effort to replace the widespread use of nano-iron oxides, which present issues, such as aggregation, and

• combatted some disadvantages of the use of iron oxides, the catalytic approach presented had handicaps that held back its broader applications [108]. In 2016, Sobhani et al. expanded on the use of iron oxide as an effective magnetic nanoparticle by creating a Cu–isatin Schiff base complex supported on nano

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

• 2013, Zhang and co-workers [67] reported the preparation of a new recyclable magnetic nanoparticle-supported antimony catalyst (γ-Fe2O3@SiO2-Sb-IL) and its application in the filtration-free, Clauson–Kaas synthesis of N-substituted pyrroles. This catalyst is fairly easy to make, air stable, and

• synthesis and proposed mechanism of N-substituted pyrroles 29. Magnetic nanoparticle-supported antimony catalyst used in the synthesis of N-substituted pyrroles 31. Iron(III) chloride-catalyzed synthesis of N-substituted pyrroles 33. Copper-catalyzed Clauson–Kaas synthesis and mechanism of pyrroles 35. β-CD

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• fluorescence emission based on CS-TPE or TBTQ-C6/CS-TPE may find applications in various fields, including the development of visual oral drug delivery systems. Keywords: chitosan; nanoparticle; tetraphenylethylene; tribenzotriquinacene; Introduction Stimuli-responsive assemblies in aqueous media have drawn

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• cancer; camptothecin; 3D spheroid; cyclodextrin; oral nanoparticle; release kinetics; Introduction Cancer is still one of the most common, highly variable and fatal diseases worldwide. Therefore, studies are continuing to develop effective/innovative and more flexible treatments for various types of

• order to imitate GIT circumstances in terms of pH and transit duration. The purpose of the release study was to elucidate the ability of the formulation to retain the encapsulated drug in the stomach and small intestine and preferably release it when it reaches the colon. The optimum nanoparticle

• for the 6-O-capro-β-CD and CS-(6-O-capro-β-CD) nanoparticle formulations, respectively. According to the Weibull model, CPT release kinetics from nanoparticles were found to be compatible with Fickian diffusion in SGF medium [36]. In the model-independent principal evaluation of in vitro release

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

• , they are less common due to their inherent toxicity and ease of oxidation. Another branch of research involving SPIONs focuses on developments in nanoscience, nanomedicine, and nanoparticle-assisted imaging, diagnosis, and drug delivery [4][5][6][7], an area that is not covered in this report. Review 1

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

• , Kottayam, Kerala, 686560, India 10.3762/bjoc.18.31 Abstract Iron- and cobalt-catalyzed Sonogashira coupling reactions are becoming central areas of research in organic synthesis. Owing to their significant importance in the formation of carbon–carbon bonds, numerous green and nanoparticle protocols have

• further classified. The Fe-catalyzed Sonogashira coupling reactions are subdivided into green protocols and miscellaneous protocols while the Co-catalyzed Sonogashira coupling reactions are further divided into nanoparticle-based strategies and non-nanoparticle-based methods. Fe-catalyzed Sonogashira

• in the presence of this nanoparticle catalyst. The work-up procedure of the reaction proceeded by “in-flask” extraction and allowed for easy recycling of the catalyst. By thermal gravimetric analysis the shelf life and catalyst stability could be measured. The reductant plays an important role for

Stepwise PEG synthesis featuring deprotection and coupling in one pot

• Logan Mikesell,
• Dhananjani N. A. M. Eriyagama,
• Yipeng Yin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2021, 17, 2976–2982, doi:10.3762/bjoc.17.207

• obtained. However, for many other applications, which include as linkers in organic synthesis and bioconjugation [8], as ingredients in nanomedicines to stabilize nanoparticles and to assist nanoparticle cell entry [9][10][11], and as PEGylation agents to stabilize drugs based on biologic molecules such as

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• efficiency. Micelles are ideal carriers when designing a nanoparticle with an abundance of functional groups on the surface, which could be conjugated with targeting ligands such as TPP. Moreover, they have already been used to successfully deliver arsenic drugs [28][29][30][31][32], highlighting their

• efficiency on a protein covered nanoparticle was significantly reduced compared to a non-protein bounded nanoparticle. Stealth like nanoparticle surfaces, such as surfaces covered with polyethylene glycol or phosphorylcholine, are therefore attractive for biological applications, as they have the ability to

• the self-assembly process [43]. Moreover, a second nanoparticle based on poly(oligo ethylene glycol methyl ether methacrylate) (pPEGMA) was generated as both polymers, pPEGMA and pMPC display protein-repellent properties [44][45]. In this paper, we aimed at comparing the effect of nanoparticles with

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• nanoparticle core directly affects the thermal response. Thus, it was found that with increasing particle size, the LCST decreases [140]. The reason for this is the strong dependence of the free space per polymer chain at the same grafting density on the degree of curvature [115]. Responsive polymers with LCST

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• and Dockendorf prepared the corresponding 2,2’-sulfur-substituted compounds 90 by reacting tryptophan amines 89 and 90 with S2Cl2 under neutral and acidic conditions, respectively (Scheme 11b and Scheme 11c) [77][78]. Kamal took a different approach using a CuO nanoparticle-supported graphene-oxide

• with 5-iodoindole (182) in the presence of thiourea and a recyclable CuO nanoparticle catalyst (Scheme 26) [116]. This heterogeneous catalysis strategy bypasses the use of unpleasant aryl thiols, which are generally coupled with other aryl halides in the presence of transition-metal catalysts for

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• reported methods require either specific nanoparticle catalysts [39][40][41][42] or the catalytic method is limited to electron-rich or electron-neutral benzylic alcohols [56]. An operationally simple method avoiding waste and potentially toxic transition-metal catalysts that is able to convert any

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

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

• employs silicon-glass and tubular reactors packed with nanoparticle supported catalysts. The apparatus allows the desired material to be prepared in 48% yield. The authors pointed out better outcomes were obtained in batch using a MgO-based catalyst, whose usage proved troublesome in flow due to clogging

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• the usefulness of aptamer-loaded LNPs to increase target cell specificity and potentially deliverability of central-nervous-system-active RNAi therapeutics across the BBB. Keywords: aptamer; blood–brain barrier; gene therapy; HIV-1; lipid nanoparticle; Introduction Lipid nanoparticles (LNPs

• low immunogenic and toxic profile and that RNA aptamers can act as potential enhancers to effectuate the delivery of LNPs into the central nervous system (CNS). Results Lipid nanoparticle development and characteristics In accordance with a previously published procedure, we generated LNPs using a

• assessed by nanoparticle tracking analysis (NTA, Table 3) and transmission electron microscopy (TEM, Supporting Information File 1, Figure S2). After postinsertion, LNP sizes were found by NTA to range from 54–66 nm (Table 3), while TEM analysis revealed average sizes between 45–52 nm (Supporting

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

• cosmetics [147]. The catalyst could be recycled, however, with reduced performance due to Pt nanoparticle oxidation. 3.1.2 Polybutadiene (PBD): Partial depolymerisation of 1,4-PBD (cis, trans, Mw 1800–500000 g⋅mol−1) was achieved by an unconventional tandem ring-opening–ring-closing metathesis route

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• - and morphology-dependent properties arising from confinement effects and strong interactions between neighboring atoms [1][2][3]. The correlation between nanoparticle size and the related electronic and optical properties has extensively been studied, leading to applications in novel technologies and

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• , these proteins can be employed as containers in delivery vehicles [100], reaction vessels [101], and bioimaging agents [102]. These containers can also be modified to produce interactions between one container to another, and thus creating building blocks for nanoparticle assembly. Künzle et al. showed

• form binary nanoparticle superlattices. a) Surface engineering of the protein container to yield either positively (right) or negatively (left) charged containers. b) Nanoparticle synthesis. The different nanoparticles are illustrated in different colours. c) Self-assembly of the different charged

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• water/methanol 1:2 (v/v). These anions caused the bright red solutions of the nanoparticles to change their color because of nanoparticle aggregation followed by precipitation, whereas halides or oxoanions such as sulfate, nitrate, or carbonate produced no effect. The sensitivity of phosphate sensing

• depended on the nature of the anion, with diphosphate and triphosphate inducing visual changes at significantly lower concentrations than hydrogenphosphate. In addition, the sensing sensitivity was also affected by the ratio of the ligands on the nanoparticle surface, decreasing as the number of

• immobilized zinc(II)–dipicolylamine groups increased. A nanoparticle containing a 9:1 ratio of the solubilizing and the anion-binding ligand showed a color change at diphosphate and triphosphate concentrations as low as 10 μmol/L, for example, and precipitated at slightly higher concentrations

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

• stabilizing dispersed metal nanoparticle catalysts, along with increased solubility in aqueous media. Very recently, we have shown that these bio-based nanomaterials could stabilize highly disperse Au species on the surface of these nanocrystals to create a highly active catalyst for aromatic nitro reduction

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• + moieties. AFM studies at pH 5.5 showed the formation of nanoparticle assemblies, which is in agreement with the loss of the secondary structure (Figure 3b). Similarly, at pH 2.2, PEP-1 also exhibited a structureless CD spectrum and irregular nanostructures (Figure S4, Supporting Information File 1). In

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

• subsequently cross-linked by oxidative homocoupling to form a highly cross-linked polymer [138]. Zhang and co-workers recently demonstrated that the dispersibility of polymer nanoparticle-supported benzothiadiazole photocatalysts could be improved in a range of different solvents by copolymerising classical

• solubility of the photocatalyst being poor in those solvents [139]. 2.4 Solid-supported semiconductors and metal nanoparticles For the same reasons outlined in the previous section, the immobilisation of thin films of semiconductors and the deposition of metal nanoparticle photocatalysts can improve the

• 2.1 and 2.2, and can be explored in detail in independent reviews [1][6][176][181][182]. Some examples are more unique, such as metal nanoparticle (NPs) photocatalysis. Despite having a conductor band structure,and therefore no band gap, the nanoscale of these materials produces visible light

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• ], iron nanoparticle-catalyzed reactions of 2-naphthol with benzaldehyde and some of its derivatives with thiourea [22], isothiocyanato oxindoles with ketones [23], ammonium isothiocyanates with chalcones [24], and α-isothiocyanato esters with α-keto amides [25]. Among the synthetic methods available for

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

• explored, with some favourable results [35][36][37][38][39][40]. Other very important aspects of Ru catalysts are mechanistic aspects, which has also favoured their exploration for directing group-assisted C–H activation reactions [40]. With respect to non-directed Ru nanoparticle-catalysed reactions

• , there are few reports. For example, the supported Ru-catalysed regiospecific C(sp2)–H arylation of benzo[h]quinolines and the addition of vinylsilanes to the C–H bonds of α-tetralones were reported by Inoue and co-workers [41][42]. Pieters et al. reported the Ru nanoparticle-catalysed C–H deuteration

• reaction of aza compounds [43][44]. Again, a Ru nanoparticle-catalysed C–H selenylation of indoles was reported by Lin et al. [45]. Herein, we report the Ru-catalysed regioselective synthesis of C3 alkenylindoles using a near-naked, surfactant-free, and recyclable Ru nanocatalyst in a heterogeneous manner

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

• electrohydrogenation of 12b that resulted in improved yield and enantiomeric purity as compared to previously reported methods (Scheme 11). In another report the same reaction was discovered to be catalyzed by applying copper nanoparticle (CuNP) as a cathode for elelctrohydrogenation of 12 [39]. The asymmetry was

• asymmetric electrocarboxylation of 4-methylpropiophenone. Enantioselective hydrogenation of methyl benzoylformate using an alkaloid entrapped silver cathode. Alkaloid-induced enantioselective hydrogenation using a Cu nanoparticle cathode. Alkaloid-induced enantioselective hydrogenation of aromatic ketones

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach. Keywords: actinometry; diarylethene; lanthanide; photochemistry; upconverting nanoparticle; Introduction The photophysical property of converting low-energy light

• knowing NYb the number of ytterbium per nanoparticle: NYb and NEr (NEr: number of erbium atom per particles) can be derived from the number of RE atoms per NP, itself computed from TEM and XRD measurements taking into account the nanoparticles size (volume ≈ 5400 ± 1000 nm3), unit cell volume (107.6 Å3

• energy of a 540 nm photon, to the emitting power of a single nanoparticle and the number of emitted photons per erbium atom J0/nEr in photon s−1. All of these numbers are gathered in Table 2, more detailed calculations are provided in Supporting Information File 1. The as-determined quantum yield is in