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

Inclusion complexes of 2-methoxyestradiol with dimethylated and permethylated β-cyclodextrins: models for cyclodextrin–steroid interaction

• Mino R. Caira,
• Susan A. Bourne,
• Halima Samsodien and
• Vincent J. Smith

Beilstein J. Org. Chem. 2015, 11, 2616–2630, doi:10.3762/bjoc.11.281

• prompted our study of this pharmaceutically relevant aspect of the bioactive compound. Here, we report original data that reflect significant solubility enhancements for 2ME effected by a range of CDs as well as comparative dissolution data in aqueous medium to highlight the potential advantages for

Chiral Cu(II)-catalyzed enantioselective β-borylation of α,β-unsaturated nitriles in water

• Lei Zhu,
• Taku Kitanosono,
• Pengyu Xu and
• Shū Kobayashi

Beilstein J. Org. Chem. 2015, 11, 2007–2011, doi:10.3762/bjoc.11.217

• -unsaturated nitriles in water. The catalyst system, which consisted of Cu(OAc)2 and a chiral 2,2′-bipyridine ligand, enabled β-borylation and chiral induction in water. Subsequent protonation, which was accelerated in aqueous medium, led to high activity of this asymmetric catalysis. Both solid and liquid

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• . A major application of the CuAAC concerns bioconjugation reactions, i.e., the covalent modification of biomolecules [6]. Such reactions typically imply water-soluble alkyne and azide reactants and should thus be performed in an aqueous medium using a water-soluble catalyst. Important limitations for

• synthesis and characterization of 1, its photoreduction properties in various solvents and illumination conditions, and its catalytic properties which reveal that 1, when illuminated, is an effective photolatent click catalyst in aqueous medium. Results and Discussion The EDA (EDA = ethylenediamine) ligand

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• dimers. The dimers and the monomers demonstrated higher activity than Trolox (10) in aqueous medium (model 3). A comparison of the studied compounds with DL-α-tocopherol (11), Trolox and curcumin is made. All dimers are characterized through lower bond dissociation enthalpies (BDEs) than their monomers

• the antioxidant action. However, the ORAC assay is a method for the detection of radical-scavenging activity based on the HAT mechanism [31][32]. From the results obtained (see Table 1) in aqueous medium there are no considerable differences in the antioxidant activities between the monomers and

• the antioxidant potential of the dimer/monomer couple. Model 3 compares the effects of monomers/dimers in the presence of an initiator (which is similar to model 1), but in aqueous medium. In this case similar antioxidant potentials for monomers and dimers and lower activity of Trolox (10) with

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• experimental results indicated that the complexes have potential activities during the degradation of the azo dyes in the aqueous medium and in the presence of hydrogen peroxide. From the preliminary data, it was found that all the prepared complexes have demonstrated a promising catalytic activity at the same

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

• Bianca Rossi,
• Nadia Pastori,
• Simona Prosperini and
• Carlo Punta

Beilstein J. Org. Chem. 2015, 11, 66–73, doi:10.3762/bjoc.11.10

• to the aqueous medium [25][27]. When we first tried to extend this procedure to the addition of alcohols other than methanol, a side reaction competed with the multicomponent mechanism, that is, the oxidation of the ketyl radical derived from the alcohol to the corresponding aldehyde. This

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• phenanthridine ring (Scheme 23). The phenanthridinium–nucleobase conjugates did not show targeted selectivity toward complementary nucleotides in aqueous medium due to the strong competition of bulk water with the expected hydrogen bonds [70][71]. Fortuitously, the hydrophobic environment within the common DNA

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

• DNA and RNA sequences. Results and Discussion Synthesis The synthetic routes to the new adenine–DBTAA conjugates AP3am and AP5 are summarized in Scheme 2, the details of which are given in the Experimental section. Spectroscopic characterisation of DBTAA derivatives in aqueous medium Novel compounds

• ] (Supporting Information File 1). Study of interactions of DBTAA derivatives with ds-DNA/RNA in aqueous medium Previous studies [11] revealed intriguing recognition of single stranded DNA dT sequences by AP3 (but not AP6, APH), whereby intercalation of AP3, AP6, APH in double stranded ct-DNA was excluded. Here