Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

• Dong-Hao Li and
• Bradley D. Smith

Beilstein J. Org. Chem. 2019, 15, 1086–1095, doi:10.3762/bjoc.15.105

• crystal structures of acene and azaacene guests inside tetralactam B with the surrounding macrocycle in chair or boat conformations [25]. Recent work has shown that water-soluble versions of anthracene tetralactam B can be threaded by water soluble squaraine dyes with very high affinities (Ka ≈ 109 M−1

• water is due primarily to a highly favorable enthalpic change [61]. Furthermore, tetralactam threading studies using water-soluble squaraine guests with flanking benzylic groups have produced Ka values that were close to 1011 M−1 [62]. The affinity gain is due to a guest back-folding effect where the

• shown that members of this tetralactam family are effective receptors for saccharides in water [65]. As shown by the X-ray crystal structure in Figure 7a, water-soluble versions of tetralactam B can nicely accommodate β-glucopyranose within the cavity [66]. There is a combination of hydrogen bonding

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• making it possible to obtain water soluble fullerenols as well as fullerenols that are still soluble in organic solvents [15][16][17][18][19]. The maximum number of OH groups, which could be attached to C60 is n = 44 [17]. Further derivatizations, where all hydroxy moieties of the compound have been

• simultaneously by using a common phase transfer reaction which enables even the combination of water-soluble substituents with the precursor C60Cl6. High yields of Janus-fullerenol derivatives bearing five defined substituents on one pole of the C60 core combined with in average 19 (+/−3) oxygen containing

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• being more deshielded (Δδ ≈ 0.026 ppm) than the others (Supporting Information File 1, Figure S14). The 6A,6B-regioisomer is also the least water-soluble. Consequently, structural verification was solely based upon the analysis of the ditosyl precursors, as discussed above. Hetero-difunctionalized β

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• of the deacetylated (water-soluble) sugars, the performance of the sugars in MGE, and the assessment of their metabolic acceptance. The studies uncovered that Ac4ManNCp is much better accepted than Ac4ManNCyoc although their membrane staining intensity after MGE is comparable. The high metabolic

• constant k2 of ManNCyoc has previously been reported to be k2 = 0.99 M−1s−1 [24]. To determine k2 of Cyc- and Cp-modified mannosamine, we synthesized ManNCyc and ManNCp according to published protocols [23][27], omitting the final peracetylation step. In this way, water-soluble compounds were obtained that

• allowed the determination of rate constants in aqueous solution. As reported for ManNCyoc, an excess of ManNCyc and ManNCp, respectively, was reacted with water-soluble tetrazine Tz-PEG-OH in acetate buffer (pH 4.7, Figure 2A). The decrease of absorption of Tz-PEG-OH at λmax = 522 nm was measured and

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• environment damaging organic solvent, but also increase the reaction rate, and provide many other technological advantages [49]. Towards this, we have chosen [bmim][BF4] and [bmim][PF6] as two model ionic liquids. Of them, [bmim][BF4] is water soluble, and [bmim][PF6] is immiscible with water. The acetylation

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• some of the most representative catalysts developed for aqueous metathesis. Water-soluble catalysts are obtained by derivatization of classical catalysts G-II and HG-II (Figure 1a), resulting from the introduction of ionic tags and highly polar groups such as ammonium tags (Figure 1b) and PEGs (Figure

• ][53]. Grubbs and co-workers were the first to introduce water-soluble catalysts which displayed metathesis activity in aqueous media [54]. In 1996, Grubbs et al. reported that complexes 1 and 2 catalyze the living opening polymerization of norbornene derivatives 35 and 36 in neat water. Interestingly

• polymer is currently being investigated for possible biomedical applications. Table 4 summarizes the activities of the different ammonium-tagged catalysts discussed above with several water-soluble substrates. Catalysts 3 and 4 showed modest to excellent activities in the RCM of N,N-diallylated substrate

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• Hibarigaoka, Tempaku-Cho, Toyohashi 441-8580, Japan 10.3762/bjoc.15.31 Abstract A reusable and highly enantioselective catalyst for the intramolecular cyclopropanation of various diazo ester and Weinreb amide derivatives was developed. The reactions catalyzed by a water-soluble Ru(II)-Amm-Pheox catalyst

• crucial for the intramolecular cyclopropanation reaction in a water/ether biphasic medium. The water-soluble catalyst could be reused at least six times with little loss in yield and enantioselectivity. Keywords: asymmetric synthesis; carbene transfer; cyclopropanation; diazoester; intramolecular

• diazoamide; Ru(II)-Pheox; water-soluble catalyst; Weinreb amide; Introduction Water-soluble transition metal complexes have been attracting increasing interest for catalytic applications because of their many advantages such as simple product separation, low cost, safety, and environmentally friendly

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation

• Łukasz Gułajski,
• Andrzej Tracz,
• Katarzyna Urbaniak,
• Stefan J. Czarnocki,
• Michał Bieniek and
• Tomasz K. Olszewski

Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16

• in water including the development of specially designed water-soluble catalysts [21][22][23][24][25][26][27][28], addition of organic solvents [29][30][31], or use of additives such as for example calixarenes or cyclodextrins [32][33], chloride salts [34], vitamin E-based amphiphiles [35

• ionic tag attached to the benzylidene ligand, with that of catalyst 1a, bearing an ionic tag placed on the N-heterocyclic carbene (NHC) fragment. As model reactions we have selected the ring-closing metathesis (RCM) of the water-soluble substrate 6, the homometathesis of alcohol 8, and more challenging

• –d) and also included catalysts having differently sized NHC ligands (2a,c). For testing the catalysts performances, we selected the RCM of the water-soluble substrate 12 (Table 2). Under the reaction conditions the classical catalyst 5 (0.25 mol %) was not soluble resulting in poor yields and

The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study

• Magdalena Jawiczuk,
• Angelika Janaszkiewicz and
• Bartosz Trzaskowski

Beilstein J. Org. Chem. 2018, 14, 2872–2880, doi:10.3762/bjoc.14.266

• a number of challenging catalytic reactions. In ruthenium-based metathesis catalysis they are often used as ammonium tags, to provide water-soluble, environment-friendly catalysts. In this work we performed computational studies on three cationic carbenes with the formal positive charge located at

• stable in water and, therefore, environmentally-friendly. The idea of incorporating a quaternary ammonium moiety into the imidazole part of the carbene was later expanded by several other groups, including a number of new water-soluble catalysts synthesized by Skowerski et al. [23][24]. In the meantime

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• Sav_K121R_N49K_A119G_T114Q_V47A (Sav_Mut) [47]. As a rescreening, the RCM reaction of a water-soluble, charged diallylamine 5 was performed. Cells harboring the Sav_WT, Sav_Mut and no Sav were tested. Whole-cell Sav_WT and Sav_Mut reached both a turnover number per cell TON(per cell) of about 300,000. Cells without Sav reached

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• , Shanghai 200444, P. R. China 10.3762/bjoc.14.198 Abstract A water-soluble 2,2′-biphen[4]arene (2,2’-CBP4) containing eight carboxylato moieties was synthesized and characterized. Its complexation behavior towards two alkaloids, palmatine (P) and berberine (B), was investigated by means of fluorescence and

• specific structures and interesting host–guest properties [21][22][23][24][25][26][27][28][29][30][31][32]. Water-soluble pillar[n]arene derivatives, especially those containing carboxylato moieties, showed low cell toxicity and good biocompatibility, and have been applied in biomedical applications such

• ’-biphen[n]arenes (n = 4–8), have been designed and synthesized [47]. To date, the complexation of biological and pharmaceutical molecules by biphen[n]arenes in water have not been reported. In this work, we wish to report the synthesis of the first water-soluble 2,2’-biphen[4]arene bearing multiple

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

• hydrophobic TTF (1) in aqueous media [65]. Another water-soluble host which can complex TTFs is cucurbit[7]uril (7) [66]. However, it is not the neutral form, but the TTF radical cation 1●+ which is preferably bound in the cavity of this host. Even the dication 12+ can be hosted by suitable macrocycles. For

• host molecule cucurbit[8]uril (9), which is enlarged by an additional glycoluril unit in comparison to 7, provides sufficient space to accommodate two planar molecules with cofacial orientation [68]. When the water-soluble TTF derivative 10 gets oxidized to its radical cation 10●+, a 2:1 complex is

• (6) ring threaded onto a water-soluble axle [80]. The rotaxane was synthesized in 23% yield by a template/capping strategy where one stopper is attached using copper-catalyzed azide–alkyne click chemistry after the formation of the precursor pseudorotaxane. Due to the hydrophobic effect, the neutral

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• ][52]. There are also examples of a radical treatment of a graphene-family material in an aqueous environment with water-soluble sodium nitrite as the additive [53][54][55][56][57]. It is well-known that, in an aqueous environment, a diazonium salt undergoes a side reaction that results in the

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• /bjoc.14.173 Abstract The synthesis of new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide fragments on the upper rim and water-soluble triazolyl amphiphilic receptors with two or four polyammonium headgroups via copper-catalyzed azide–alkyne cycloaddition reaction has been

• high affinity to ATP [26]. Herein we report the synthesis of new amphiphilic water-soluble calix[4]arene derivatives with cone conformation containing two or four polyammonium groups on the upper rim by using a click chemistry approach and the results of binding studies toward nucleotides in aqueous

• groups in the 1H NMR spectra fully corresponded to the proposed structures of 9 and 11 (Supporting Information File 1, Figures S9, S10, S13, and S14). The polyamines 10a,b and 12a,b were obtained in high yields after BOC deprotection with HCl in dioxane as water-soluble di- and tetrahydrochlorides

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• transfer; supramolecular chemistry; Introduction Cucurbit[n]urils (CBn, n = 5–8, 10, and 14) are a class of macrocyclic host molecules which are water soluble, nontoxic, and are able to bind a large variety of neutral and cationic guests in their inner cavity with high affinity [1][2][3][4]. This unique

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• arbitrarily as we have frequently employed them to optimize mass spectrometric procedures. Also, we were interested to test, if threonine or tyrosine residues, respectively, would lead to better labeling efficiency. Because mannoside 3 is poorly water soluble, it was dissolved in methanol and then added to

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

• their SCS analogues, SNS pincer complexes are poorly studied for their use in coupling reactions. Accordingly, a series of water soluble cationic Pd(II) SNS pincer complexes have been successfully synthesised and investigated in detail for their catalytic activity in Suzuki–Miyaura coupling reactions

• microwave heating [7][8][9][10][11][12][13][14][15], ultrasonication [16][17][18], ligand-free methodologies [19][20][21][22][23][24][25] and the use of water-soluble palladium pre-catalysts/catalysts [26][27][28][29][30]. The latter is the preferred choice since it allows for the reusability of the

• the literature are the water-soluble pincer complexes 14, 15 and 16 (Figure 2a). While pincer complex 14 provided moderate (38–68%) GC yields over 6 h at 75 °C using 2 mol % catalyst loading with inactivated aryl bromides, pincer complex 15 was found to be incompatible with both activated and

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• to their facial modification, Prof. Böhmer demonstrated calixarenes as having “(almost) unlimited possibilities” [17]. We have focused on molecular recognition and self-assembly of water-soluble calixarene derivatives for a long time [18][19][20][21][22][23][24], directed by exploring biomedical

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• high yielding N-arylation of 1H-1,2,3-benzotriazole (BTA), utilizing symmetrical diaryl-λ3-iodanes as two-fold aryl donors has been reported in the presence of Pd(OAc)2 and TPPTS as a water-soluble ligand, and copper(II) phenylcyclopropylcarboxylate (Scheme 35) [74]. Noteworthy, it is mentioned that Ar

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• , thereby changing the efficiency of the FRET process between the two fluorophores and exhibiting a significant red shift in the emission spectrum. Moreover, the conjugate 43 could be used as an attractive tool for imaging of nuclear DNA in the cells due to its low cytotoxicity. A series of water-soluble

Polysubstituted ferrocenes as tunable redox mediators

• Sven D. Waniek,
• Jan Klett,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86

• for oxidation or reduction processes, respectively. This avoids the often kinetically hindered direct ET between electrode and substrate and diminishes overoxidation or overreduction of the substrate. Redox-active ferrocenyl derivatives find application in redox flow batteries [15], with water soluble

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

• encapsulated and the best results were achieved when the enzyme was in the lumen (Figure 3b), highlighting the advantage of enzyme compartmentalization and shielding. The explanation for this improved performance is the enlarged contact area between (hydrophobic) substrate and (water soluble) enzyme. Moreover

• . The utility of these dendrimers in hydrogenation reactions resulted in efficient reactions that proceeded with unprecedented selectivity of 99%. Moreover, this system is one of the first of bimetallic catalytic systems to be used for hydrogenation reactions in water. Water soluble dendrimer-stabilized

• (X = I or Br) in water [100]. Other examples of water-soluble dendrimers are peptide- and glycol-based dendrimers [102][103]. As a result of their compositional versatility, they have been reported in many applications for biomedical engineering (e.g., glycopeptide dendrimers for drug delivery [104

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• stabilisation of dispersed drops in a continuous phase. In 2010, Crossley et al. [29] put forward the idea that catalyst particles may both act simultaneously as an emulsifier in Pickering emulsions and serve as the catalyst in which water-soluble reactants and oil-soluble reactants react at the oil–water

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

• , the 3'-amine was protected with an azidomethyloxycarbonyl (Azoc) protecting group. This protecting group can be rapidly removed under non-denaturing conditions after incorporation by the complementary nucleotide using the Staudinger reaction with a water-soluble phosphine (Figure 11). This protocol

• assay is another approach to avoid stalling due to inhibition. As mentioned in the Introduction, ligation reactions had been achieved by Naylor and Gilham in aqueous media in presence of a water-soluble carbodiimide as condensing reagent [7]. Likewise, Sulston et al. had used EDC to oligomerize AMP in

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