Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• et al. described a nanogel composed of poly(N-isopropylacrylamide) brushes grafted on Pd-NPs (Pd@PNIPAM) to carry out coupling reactions in water under mild conditions [120]. They showed highly efficient coupling of several hydrophobic aryl halides with phenylboronic acid, which in all cases resulted

• in yields above 70%. Moreover, the Pd@PNIPAM nanoreactors could be easily recycled thanks to the reversible phase-transition of the polymeric brushes [112]. Que et al. reported the synthesis of gold nanoparticles (Au NPs) sheltered in PEG-PS nanogels for the reduction of 4-nitrophenol (4NP) [121

• ]. Thiol functionalized PEG blocks were immobilized on Au NPs. PS segments improved the stability of the system and provided the necessary hydrophobic environment that is required to undertake the reduction reaction in water. The outcome of using Au@PEG-PS as nanoreactors was compared to those resulting

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• acid nanoparticles (ASA NPs) proved to be efficient under neat conditions for the synthesis of 1-amidoalkyl-2-naphthols [19]. Zali et al. carried out this synthesis applying nano-sulfated zirconia [20], Borhade et al. used PbS nanoparticles [21], while Safari et al. applied magnetic-nanoparticle

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• ; click chemistry; glyco-gold nanoparticles; triazole; Introduction Metal nanoparticles (NPs), with their unique physicochemical properties, have drawn significant interest in recent years, and are expected to form the basis of many biological and technological innovations during the remainder of the

• 21st century [1]. Gold nanoparticles (AuNPs) are one of the most significant and stable classes of metal NPs [2] and have potential applications in optics [3], biology [4] and catalysis [5]. Carbohydrates are one of the classes of molecules that are essential for life. Although they are involved in

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• , Jadavpur, Kolkata 700032, India. Fax: +91 33 24730957; Tel: +91 33 23223403 10.3762/bjoc.13.174 Abstract The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous

• catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the

• agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. A correlation of loading of Ni species, size of NPs and the intermediate Ni-related heterostructures formed during the

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• (NPs) of transition metals have been introduced as eco-catalysts in several reactions [20]. The NPs became a useful tool for catalytic transformations due to their excellent performance, which is related to their small size and a high surface-to-volume ratio [21][22][23][24][25]. Moreover, they are

• relatively easy to prepare and can be obtained in different size and morphology by essentially controlling the synthetic method and experimental conditions. As a result of the excellent catalytic activity of NPs, they can be used under mild and, in some cases, in environmental sustainable conditions. In

• particular, Pd NPs have been well-established as catalysts in the Mizoroki–Heck coupling reaction, obtaining the desired products in good to high yields, finding some examples in aqueous solution and under microwave (MW) irradiation [26][27][28][29][30][31][32][33][34][35][36]. Besides these studies, there

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

• Ana Franco,
• Sudipta De,
• Alina M. Balu,
• Araceli Garcia and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1439–1445, doi:10.3762/bjoc.13.141

• and f) 1% Co/RGO. Powder XRD patterns of RGO supported Fe and Co NPs. IR spectra of 1% Fe/RGO and 1% Co/RGO catalysts collected by using diffuse reflectance infrared transform spectroscopy (DRIFT) at room temperature. Textural properties of RGO and NPs supported RGO materials. Results for the

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• nucleosides [23][24]. The enzymes typically employed for these purposes are nucleoside phosphorylases (NPs) or nucleoside deoxyribosyltransferases (NDTs) in the presence of inorganic phosphate in a tandem enzymatic process [25]. In Scheme 5 we highlight a very recent example of this methodology for the

• synthesis of modified pyrimidine nucleosides using E. coli NPs [26]. 2.2 Synthetic strategies The classical protecting-group-free (pre-2000) synthetic strategies are dated back to well over 100 years with the discovery of the Fischer glycosylation (Scheme 6) [27][28]. Methanol can be glycosylated with D

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• NPs exhibit elevated specific accumulation in comparison to spherical ones [54]. Recently, Kikkeri et al. published two interesting papers evaluating the impact of the AuNP shape on the carbohydrate presentation and activity [24][55]. In the first work the authors reported the employment of GAuNPs for

• the bacterial recognition and bacterial infection inhibition. Three different morphologies of AuNPs (sphere, rod and star-like NPs) coated with galactose and mannose derivatives were employed for the quantification of their binding affinity to E. coli, suggesting that each shape could induce a

• metallic NPs. Carbohydrate–carbohydrate interactions (CCIs), generally characterized by KD values in the millimolar range, are very difficult to detect. Updated data confirm the crucial role of these bindings in the regulation of many cellular processes [72], however, researches related to the use of

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• chroman unit occurs widely as a privileged framework in a large number of natural products (NPs), natural product-like molecules (NPLMs) and pharmaceuticals, possessing diverse biological activities [1]. (+)-Brazilin (1) and (−)-haematoxylin (2) are two structurally-related tetracyclic homoisoflavonoid

• as the key step is part of our long term objective of synthesizing chroman-based NPs and NPLMs and their subsequent application in medicinal chemistry. Like chroman, the tetralin unit has been recognized as privileged structure. We were interested to synthesize cis-6a,7,8,12b-tetrahydro-6H-naphtho

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• and comparison of the data with DFT calculations, while ECD spectroscopy was found to be inconclusive in this case. The enantiomeric purity of samples from test purchases and police seizures was assessed by a self-developed chiral HPLC method. Keywords: chiral HPLC; ECD spectroscopy; NPS; synthetic

• and serve as a marijuana substitute with the intention to circumvent the narcotics regulations. Within the past years, the number of registered new psychoactive substances (NPS) has increased tremendously and currently lies around 600, 98 of which have only appeared in 2015 [3]. In response, the

• European authorities collaborate closely in terms of information exchange, risk assessment and control of NPS [4]. The first substance reported to the European Early Warning System (EWS) of the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) in this context was JWH-018 (1, Figure 1

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

• Vincent M. Rotello

Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161

• stuff found in cells [68]. This was the start of a collaboration that continues to this day, where we have used laser desorption ionization (LDI) to characterize ligands on particles [69][70], supramolecular chemistry in cells [71], track NPs in fish [72] and plants [73], and to image NPs in animal

Towards potential nanoparticle contrast agents: Synthesis of new functionalized PEG bisphosphonates

• Souad Kachbi-Khelfallah,
• Maelle Monteil,
• Margery Cortes-Clerget,
• Evelyne Migianu-Griffoni,
• Jean-Luc Pirat,
• Olivier Gager,
• Julia Deschamp and
• Marc Lecouvey

Beilstein J. Org. Chem. 2016, 12, 1366–1371, doi:10.3762/bjoc.12.130

• bifunctional molecules substituted by amines, thiols, carboxylates, sulfonates, phosphonates or bisphosphonates [5][6][7]. Particularly, a strong interaction between the NPs and the phosphonic moiety was observed and more interestingly the best results were obtained with bisphosphonate products [8][9]. For the

Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• conditions and MTT assay, crystallographic data for compounds 25, 28, 29, and 41, and dose-response curves. Supporting Information File 36: NMR spectra for compounds 1, 2, 4–8, 12, 18–22, 25, 26, 28, 29, 31, 40–46, and 48–51. Acknowledgements This work was supported by the project MEYS – NPS I – LO1413 and

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• 4 with ferricenium hexafluorophosphate led to a stable biferrocenium polymer while oxidation with Au(III) or Ag(I) allowed the formation of networks with nanosnake morphology, consisting of mixed-valent Fe(II)–Fe(III) polymers that encapsulate metal (Au or Ag) nanoparticles (NPs). These polymers

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• Sciences, University of Padova, INSTM, Via Marzolo 1, 35131 Padova, Italy Department of Chemistry, University of Hamburg, Institute of Physical Chemistry, Grindelallee 117, 20146 Hamburg, Germany 10.3762/bjoc.11.77 Abstract A common approach to generate tailored materials and nanoparticles (NPs) is the

• PEG, a sulfobetaine and an adamantyl group. The potential of these conjugates has been demonstrated with the immobilization of tripodal catecholates on ZnO NPs. The results confirmed a high loading of tripodal PEG-catecholates on the particles and the formation of stable PEG layers in aqueous solution

• effector-conjugates of tripodal catecholates and their immobilization on ZnO NPs. Results and Discussion Zinc oxide belongs to the most intensively investigated inorganic compounds, due to its outstanding functional properties combined with manifold morphologies, no toxicity and easy preparation [16]. It

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• photosensitizer (PS) molecules present (NPS) to the total number of absorbed photons (Nabs). It could be expressed by the following equation: where V is the volume of the irradiated solution. The absorbed photon concentration is given by: where I0 is the incident light intensity on the cell (9 mW·cm−3, i.e., 4·10

Silica: An efficient catalyst for one-pot regioselective synthesis of dithioethers

• Samir Kundu,
• Babli Roy and
• Basudeb Basu

Beilstein J. Org. Chem. 2014, 10, 26–33, doi:10.3762/bjoc.10.5

• by silica NPs, where a single example of a reaction of an allyl bromide and excess benzenethiol was studied [41][42]. The reaction was carried out in the presence of silica NPs and water, and they isolated 1,3-dithioether by an anti-Markovnikov addition. However, there is no report on the metal-free

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

• catalysts for organic synthesis. Recently, CNCs have been used as an effective support for Pd nanoparticles [31], AuNPs [32], SeNPs [33], NiNPs [34] and Au–Ag alloy NPs [35] for greener organic synthesis. However, to date, studies on combining the surface chemistry of CNCs with metal nanoparticles in

Synthesis of the calcilytic ligand NPS 2143

• Henrik Johansson,
• Thomas Cailly,
• Alex Rojas Bie Thomsen,
• Hans Bräuner-Osborne and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 1383–1387, doi:10.3762/bjoc.9.154

• ICORE) UFR des Sciences Pharmaceutiques, Bd Becquerel, F-14032 Caen, France 10.3762/bjoc.9.154 Abstract (R)-3 (NPS 2143) is a negative allosteric modulator of the human calcium-sensing receptor (CaSR) and as such represents an important pharmacological tool compound for studying the CaSR. Herein, we

• optical purity (er > 99:1) as demonstrated by chiral HPLC and the pharmacological profile for (R)-3 is in full accordance with that reported in the literature. Keywords: epoxides; GPCR; NPS 2143; nucleophilic aromatic substitution; pyrylium chemistry; Introduction The first G-protein-coupled receptors

• its biological activity (Figure 3). Conclusion Herein, for the first time, we disclose a detailed, reproducible and scalable synthetic procedure for the calcilytic ligand (R)-3 (NPS 2143) making this important pharmacological tool compound readily available to the scientific community. All compounds

Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features

• Laura Bekere,
• David Gachet,
• Vladimir Lokshin,
• Wladimir Marine and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2013, 9, 1311–1318, doi:10.3762/bjoc.9.147

• electron-donating properties and weaker electron-accepting properties than ZnO [18]. Grafting to the surface of ZnO nanoparticles In order to investigate the behavior of acid 4 as a fluorescent molecular probe, preliminary experiments on grafting to the surface of ZnO nanoparticles (NPs) were carried out

• . The ZnO NPs in ethanol were prepared by laser ablation according to [14]. The typical NP size was 17 nm with the dispersion about 25%. A freshly prepared ZnO NP solution in ethanol was added to the 1.4 × 10−6 M solution of 4 in ethanol. Under one-photon CW excitation at 325 nm, the fluorescence

• addition of ZnO NPs (solid curve). Excitation wavelength: 325 nm. The inset shows the same normalized spectra. Synthesis and structures of 1,8-naphthalimides. Possible ionization and complexation of 4 in ethanol. Optical properties of derivatives 1–4, 6 in ethanol. Solvent-dependent optical properties of

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• of the commercial importance of p-aminophenol, improvement of catalytic performance was attempted by using nanoparticles (NPs) of Au, Pd, and Ni immobilized on various solid supports. Apart from the use of gaseous H2, the reduction of p-nitrophenol with sodium borohydride (NaBH4) was studied

• catalyzed with core–shell Au–Pd NPs and Au NPs [23][24][25][26]. Formic acid is another attractive H2 source because it is safe, easy to handle, and requires no high-pressure equipment. Formic acid and formate have been used as effective H2 donors in the catalytic transfer hydrogenation of aromatic nitro

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• ] are expected to benefit from the unique properties and promises offered by nanoparticles. Of course, in order to exploit the exciting properties of NPs, it is almost always necessary to incorporate them into a more complex structure, often through the use of a suitable organic coating, which not only

• imparts stability against aggregation but also other important features such as solubility, modularity, and optical and self-organisation properties. The organisation of NPs into ordered systems is of crucial importance for their use in high-technology applications and devices, and a wide variety of "top

• -down" and "bottom-up" methods have been proposed and are continuously under development [17][18][19][20]. Central to these efforts is a consideration of the forces acting upon the NPs [21][22], which are determined by their composition (surface chemistry, magnetic/electrostatic properties) and

Symmetry breaking and structure of a mixture of nematic liquid crystals and anisotropic nanoparticles

• Marjan Krasna,
• Matej Cvetko and
• Milan Ambrožič

Beilstein J. Org. Chem. 2010, 6, No. 74, doi:10.3762/bjoc.6.74

• Sobota, Slovenia 10.3762/bjoc.6.74 Abstract Orientational ordering of a homogeneous mixture of uniaxial liquid crystalline (LC) molecules and magnetic nanoparticles (NPs) is studied using the Lebwohl–Lasher lattice model. We consider cases where NPs tend to be oriented perpendicularly to LC molecules

• due to elastic forces. We study domain-type configurations of ensembles, which are quenched from the isotropic phase. We show that for large enough concentrations of NPs the long range uniaxial nematic ordering is replaced by short range order exhibiting strong biaxiality. This suggests that the

• impact of NPs on orientational ordering of LCs for appropriate concentrations of NPs is reminiscent to the influence of quenched random fields which locally enforce a biaxial ordering. Keywords: liquid crystals; nanoparticles; orientational order; quenched disorder; symmetry breaking; Introduction The