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

• efficient and reusable catalyst for rapid oxidation of a series of aromatic and aliphatic sulfides at room temperature under aqueous medium. The simplicity of the process, chemoselectivity towards sulfoxides, and recyclability at least for eleven runs were the merits of this procedure [61]. Zhou et al

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• species, where not characterized in aqueous medium at room temperature before. A similar observation regarding TTF dimers was made by Fujita and co-workers in 2005 [69]. They used the self-assembled Pd-cage 11 to encapsulate two neutral TTF molecules. Oxidation of the solution yields an ambient-stable TTF

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

• Zheng-Yi Li,
• Hong-Xiao Tong,
• Yuan Chen,
• Hong-Kui Su,
• Tangxin Xiao,
• Xiao-Qiang Sun and
• Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

• , this may offer us the opportunity to improve the green aspect of many reactions both in organic and aqueous medium [30]. For example, it has been reported that calixarenes linked with thiourea groups can be used to catalyze asymmetric Aldol reactions or Michael addition reactions in recent years [31

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• partners in aqueous medium. All the complexes could catalyse the Suzuki–Miyaura coupling reaction to provide the corresponding biaryls in excellent yields with only 0.5 mol % catalyst loading. Furthermore, unlike the previously reported SNS pincer Pd(II) complexes, the catalysts in the current study were

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• , their sequestration abilities were tested in aqueous medium at different pH values, in order to assess their possible pH-tunable properties, towards a set of structurally diverse organic guests (4-nitroaniline derivatives 1–5 and dyes 6–10, Scheme 2) which were suitably selected as possible pollutant

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• an oxidation reaction dissolved O2 is consumed rapidly and diffusion of O2 into the reaction medium can easily become overall rate-limiting. The O2 diffusion rate into the reaction medium directly correlates with the interfacial area between aqueous medium and the gas phase. Large interfacial surface

Enzyme-free genetic copying of DNA and RNA sequences

• Marilyne Sosson and
• Clemens Richert

Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47

• . It involves the incorporation of nucleotides at the terminus of a primer and is directed by base pairing. The reaction occurs in aqueous medium and leads to phosphodiester formation after attack of a nucleophilic group of the primer. Two aspects of this reaction will be discussed in this review. One

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• subsequent treatment with NaN3 in aqueous medium to give azido oxazoles in good selectivity. Process integration enabled the synthesis of this useful moiety in short overall residence times (7 to 9 min) and in good overall yields. Keywords: azirines; continuous flow; heterocycles; oxazoles; process

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• ]. The study was essentially performed with oligothymidylate models. First, the internalization of a 5’-fluorescein fma (Tps)14T in Vero, HeLa and GC-2 cells was poor but comparable to that of the control 5’-fluorescein (Tps)14T. These data can be explained by the decreased solubility in aqueous medium

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• all components in air, the environmentally friendly nature, and the recycling of the aqueous medium. Subsequently, the group of Li and Duan [58] reported an efficient method for the synthesis of α-trifluoromethyl ketones via addition of CF3 to aryl(heteroaryl)enol acetates using readily available

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• tert-butyl hydroperoxide and a catalytic amount of Cu(II), but with 10 mol % of tetramethylethylenediamine (TMEDA). Organic solvents were replaced by pure water and the aqueous medium can be recycled up to five times. The substrate scope was large when tertiary amides were used. A secondary arylamide

• temperature. The trifluoromethyl radical was generated from CF3SO2Na and t-BuOOH. In comparaison to Baran’s results, in all cases, the yields were improved. Advantageously, the aqueous medium can be recycled (Scheme 37) [60]. Even though it is a proven fact after 2011 and Baran’s work that no-added metal

Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2017, 13, 2442–2457, doi:10.3762/bjoc.13.241

• . Although the yield increased, it remained low (20%). The poor yields in the aqueous medium are explained by the high reactivity of the diazomethane species, which favors nonspecific reactions in water [52]. Very recently, more specific diazomethane reagents for water-tolerant esterification have also been

• compromised kinetic stability is likely for the partially fluorinated ester groups. Next, we determined the half-life values following the above mentioned kinetic model for esters 1–5 in aqueous medium at pH 11 and 298 K (Figure 2). In accordance with previous reports, we found that the ethyl ester hydrolyzed

• AcGlyGlyProGlyGlyNH2 [71] and AcGlyProOMe [68] compounds when measured in deuterium oxide. For 1–5, we found the trans/cis ratios ≈ 5 for all five esters when measured in aqueous medium; the kinetic parameters of the amide rotation were also nearly identical (Table 2). We then noticed that the trans/cis ratios

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

• ), the use of water or aqueous systems as solvent in organic synthesis to replace hazardous and expensive organic solvents have been explored [39][40]. Various catalytic systems have been reported for the Mizoroki–Heck reaction in aqueous medium [41][42][43]. However, a drawback of using water is related

• H2PdCl4 in the presence of poly(N-vinylpirrolidone) (PVP) [46][47]. These Pd NPs exhibited highly efficient catalytic activity in Suzuki–Miyaura coupling reactions [46][47] and nitroaromatic hydrogenations [48] in aqueous medium. Outstanding performance of these PVP-Pd NPs in the coupling reaction was

• electrochemical synthesized PVP-Pd NPs for Mizoroki–Heck coupling reaction. By the efficient coupling reaction with aryl bromides, many stilbenes and novel hetero-stilbenes were obtained employing the Pd NPs in aqueous medium under relatively mild conditions, using MW irradiation. Results and Discussion The PVP

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

• fashion [58][59]. Therefore, they postulated that by using the correct divalent cation and suitable Lewis acid/Lewis base pairing, the necessary transition-state organization to favor glycosylation of a glycosyl fluoride would outcompete hydrolysis in the aqueous medium. This would lead to a simple non

Conjecture and hypothesis: The importance of reality checks

• David Deamer

Beilstein J. Org. Chem. 2017, 13, 620–624, doi:10.3762/bjoc.13.60

• solution, rather than by evaporation to dryness. However, polymerization in an aqueous medium requires chemical activation of the monomers, and so far there is no obvious mechanism by which activation can occur. Recent studies have returned to evaporation as a way to drive polymerization reactions [21][22

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• using the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The molecular conjugates, well soluble in aqueous medium, were extensively characterized by 1D and 2D NMR spectroscopy and mass spectrometry. Preliminary spectroscopic investigations showed that the β

• aqueous medium, which precludes any response to light excitation. Keywords: β-cyclodextrins; fluorescence; photodynamic therapy; photosensitizers; singlet oxygen; xanthene; Introduction Cyclodextrins (CDs) are cyclic oligosaccharides able to form host–guest inclusion complexes with drugs and this

• corresponding 4–β-CD conjugate did not show either detectable fluorescence emission or 1O2 photogeneration. This is not surprising in light of the observed massive aggregation of this derivative in aqueous medium (see Figure 5). Studies currently in progress are addressed to better clarify this point and to

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• , sterols, fat-soluble vitamins, phospholipids, mono-, di- and triglycerides, etc. Their amphiphilic nature causes the molecules of certain lipids to organize into liposomes when they are in aqueous medium. This property allows the formation of biological membranes. Indeed, cells and organelles membranes

Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

• Vladimir A. Stepchenko,
• Anatoly I. Miroshnikov,
• Frank Seela and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254

• -thiouracil and 2-thiouracil in aqueous medium were analyzed by the UV and IR spectroscopic methods and the structure 6 with charge delocalization for the former and two tautomeric monoanions 7a and 7b (ca. 1:1) with charge localization on the C-4 oxygen atom for the latter were suggested [48][49] (Figure 3

• concentrations and is not presented on the plot. Supposed monoanionic forms of 4-thiouracil and 2-thiouracil in aqueous medium [48][49]. Phosphorolysis of 6-aza-2-thiothymidine (5b), 4-thiothymidine (11a) and 4-thio-2′-deoxyuridine (1b) by E. coli TP for extended time period (for details, see caption of Figure 2

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• ) into its fragments (III in Figure 5b) increased to −11 kcal/mol in aqueous medium. This might explain the increased hydrolysis rate of this compound in acidic media compared to compound 8a’. In contrast to 8a, the hydrolysis of the neutral tetrahydroquinazoline 13b (I in Figure 5b) into its neutral

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• at 110 °C for 10 min in aqueous medium. In both cases, the desired α,β-unsaturated ketone 2 were isolated in similar yields (see Table 1). It is worth mentioning here that the microwave-assisted reaction was performed in aqueous medium, an environmentally benign solvent. The other advantage of this

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• 2-alkynylbenzaldehyde 100, aniline (32) and diethyl phosphonate catalyzed by C12H25SO3Na–CuSO4 (10 mol %) or Ag(C12H25SO3) (10 mol %) under ultrasonic conditions in an aqueous medium afforded the desired 1,2-dihydroisoquinolin-1-ylphosphonate 101 in 65% and 79% yields, respectively. A more detailed

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• -workers described the asymmetric α-alkylation of aldehydes with 3-indolyl-3-hydroxyoxindoles in aqueous medium in the presence of catalytic MacMillan catalyst (10 mol %, cat. 41), affording the desired products in good to excellent yields (62–98%) and with moderate diastereoselectivities (up to 70:30 dr

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• absorbance difference measured at 337 nm in presence and in absence of CDs are summarized. As explained in [31], this change of absorption can be attributed to host–guest type interactions, during which the guest changes its environment from an aqueous medium to the apolar CD cavity inducing the variations

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• aliphatic side chains was used by Iwamoto and co-workers for promoting benzoin reactions in aqueous medium. The improved reactivity was attributed to the formation of micelles from the hydrophobic alkyl chains of the catalyst in aqueous medium. The reaction proceeded well with various aromatic and

• heteroaromatic aldehydes (Scheme 3) [11]. Subsequently, the same group disclosed the application of bis(benzimidazolium) precursor 8 as a more efficient catalyst for the benzoin condensation in aqueous medium. Here, the NHC precatalyst incorporated a long aliphatic bridge between the two imidazolium entities

• developments in the rapidly growing realm of NHC-catalysis. Breslow’s proposal on the mechanism of the benzoin condensation. Imidazolium carbene-catalysed homo-benzoin condensation. Homo-benzoin condensation in aqueous medium. Homobenzoin condensation catalysed by bis(benzimidazolium) salt 8. List of assorted

Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes

• Norbert Vida,
• Jiří Václavík and
• Petr Beier

Beilstein J. Org. Chem. 2016, 12, 110–116, doi:10.3762/bjoc.12.12

• [27]. As already mentioned, compound 3 is much more stable in acidic than in neutral or basic aqueous medium. To investigate its reactivity in acids under various conditions, several screening experiments were carried out. In HCl (5 M), H2SO4 (5 M or 10 M) or 85% H3PO4 at ambient temperature the