Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• normally be present at a substantial initial concentration (even though a non-aqueous medium is usual). The reactant B will be an alcohol. Figure 8 shows some progress curves for plausible conditions and enzyme parameters under which the product ee deviates noticeably from 0.95 expected for the value of E

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• ). The synthesis of indoline-spiro fused pyran derivatives 53 was reported by Jiang and co-workers [57] employing a multicomponent reaction between substituted isatins 35, cyclic 1,3-diketones 6 and malononitrile (51) in an aqueous medium without any catalyst. Reaction diversity was examined by using

Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders

• David Straßburger,
• Svenja Herziger,
• Katharina Huth,
• Moritz Urschbach,
• Rainer Haag and
• Pol Besenius

Beilstein J. Org. Chem. 2021, 17, 97–104, doi:10.3762/bjoc.17.10

• Research Center of Electron Microscopy, Freie Universität Berlin, Fabeckstr. 34a, 14195 Berlin 10.3762/bjoc.17.10 Abstract The synthesis of a sulfate-modified dendritic peptide amphiphile and its self-assembly into one-dimensional rod-like architectures in aqueous medium is reported. The influence of the

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

• solutions can be manipulated to result in different polymorphs [35], 3D crystals with dissimilar structures and morphologies. We envisaged that the crystallization of 1 in a basic aqueous medium can lead to 2D arrays (bilayers) due to the higher solubility of the assemblies as a result of the charged

• , followed by the immediate evaporation of THF in a high-vacuum and adding water to reach a 1 × 10−4 M concentration. The self-assembly is instantaneous, as indicated by a color change from bright orange to pink in all systems. UV–vis spectra of compound 1 in aqueous medium exhibit a 0-0/0-1 vibronic band

• together, and the carboxylic groups of both PDIs turn outwards to the surrounding aqueous medium. The resulting 1D π-stacked bilayer structures interact via the ethylpropyl residues to form an extended bilayered crystalline sheet (Figure 3C,D,E). According to the model (Figure 3C,D,E), dark-contrast

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

• NPs. A one-pot synthesis method was used to both deposit Pd salts and reduce them into NPs onto the support material. First, PdCl2 was mixed for 15 min with either ChNC or ChsNC in an acidic aqueous medium to form a dark yellow mixture. This step facilitated coordination of Pd salts onto the support

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• structure in which the citronellyl–dodecanyl linker is located in the phospholipid membrane, and the mannose and the NBD are positioned in the surrounding aqueous medium. The close proximity of the NBD fluorophore to the membrane–water interface [30][31] allows for fluorescence-based scramblase assays

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• compounds was opposed to that observed with the TPA topical model. This may be a consequence of the lower lipophilicity of 3 (clogP = 0.58) and 4 (clogP = 1.39) compared to 5 (clogP = 1.80) and 6 (clogP = 1.85), influencing the better dissolution of 3 and 4 in an aqueous medium prior to its absorption

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• reaction proceeds under mild conditions, is effective, efficient, and requires no column purification in many cases. The Cu alkyne–azide cycloaddition (CuAAC) version also gives only 1,2,3-triazole products substituted at the 1- and 4-positions in an aqueous medium even at room temperature and requires no

• -functionalized silica 46 was added to the mixture, and this was heated to reflux to generate the catalyst 48. Several organic halides or epoxides, nonactivated alkynes, and sodium azide were reacted in an aqueous medium to provide triazoles or β-hydroxytriazoles using 1.0 mol % catalyst loading at 25 °C

• in an aqueous medium under aerobic conditions at 70 °C (Scheme 20). In another example, GO was effectively modified with CuO nanoparticles through a facile pathway that can be seen below [83]. In the next step, GO was sonicated in isopropyl alcohol for 0.5 h to produce a black dispersion. After

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• Daria V. Berdnikova Department Chemie–Biologie, Organische Chemie II, Universität Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany 10.3762/bjoc.15.275 Abstract A series of hemi-indigo derivatives was synthesized and their photoswitching properties in aqueous medium were studied. The

• with their poor solubility and reduced photoswitching efficiency in aqueous medium. In many cases, approaches to improve the water solubility by chemical modification of the photochromic scaffolds are not straightforward because the introduction of substituents often interferes with the desired

• photochemical properties. Along these lines, special efforts have been devoted to design, for example, water-soluble derivatives of spiropyran [1][2][3], azobenzene [4][5], diarylethene [6][7][8], or chromene [9] that keep efficient photochromism in aqueous medium. Although a significant progress has been made

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• cationic dyes was synthesized and investigated with respect to their optical properties, propensity to aggregation in aqueous medium, and capacity to serve as fluorescence “light-up” probes for G-quadruplex (G4) DNA and RNA structures. Among the 61 compounds, 57 dyes showed preferential enhancement of

• absorption bands of most dyes are blue-shifted by 10 to 30 nm and undergo a hypochromic effect, compared with organic solvents such as MeOH or DMSO. This behavior evidences a more or less significant aggregation propensity of dyes in aqueous medium, even though, in all tested cases, no visible precipitation

• a set of G4-DNA and G4-RNA analytes, as well as the respective non-G4 controls. The data were analyzed aiming at the identification of structural motifs or physical properties (such as aggregation in aqueous medium) of dyes which could govern their fluorimetric response towards one or another group

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• face with primary hydroxy groups and a wider secondary face with secondary hydroxy groups [6][7]. With the hydrophobic cavity and the hydrophilic hydroxy groups, CDs efficiently form host–guest complexes with different hydrophobic guests in aqueous medium [8][9]. Among the common CDs, γ-CD possesses a

• interested in exploiting the binding capability of γ-CD in the construction of high order [n]rotaxanes and [n]catenanes. Here, we report our work on the synthesis of multiring, hetero[n]rotaxane containing γ-CD and cucurbit[6]uril (CB[6]) as the macrocyclic components in an aqueous medium. Because of the

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• [105][106]. Inspired from the history of IP synthesis Tajbakhsh et al. have utilized the biimidazole Cu(I) complex supported on magnetic Fe3O4 (MNP@BiimCu) as a heterogenous catalyst for the synthesis of imidazo[1,2-a]pyridine in an aqueous medium (Scheme 9) [107]. By their approach, they have avoided

• in an aqueous medium (Scheme 9). In order to increase the solubility of reactants in aqueous medium cationic surfactant (cetyl trimethylammonium bromide: CTAB) has been used which has also increased the yield of the product. Aliphatic aldehydes resulted in lower yields (65 and 76%) whereas

• product. This was an unprecedented report for the synthesis of a library of targeted moieties using a nano-click catalyst. The triazole precursor was also synthesized by the group using nano-copper oxide in an aqueous medium. The reaction has well tolerated variedly substituted starting materials whether

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• synthesis of diversely functionalized pyrroloacridinones in aqueous medium. A library of compounds was synthesized in a one-step pathway utilizing 10 mol % of the nanoreactor following a sustainable methodology in water with high yields. Keywords: heteroditopic macrocycle; organocatalyst; nanoreactor

• reactants. In fact, encapsulation can result in the stabilization of a specific transition state by stripping it out from solvent molecules [13][14]. Hence, in aqueous medium, the syntheses of nanoreactors with a covalent organic framework is important, which is indeed a difficult task due to their large

• mmol) and p-toluidine (3a, 1 mmol) in water under different conditions (Table 1). Importantly, the catalyst BATA-MC showed excellent efficacy affording the desired product 4a in high yields in aqueous medium (Table 1, entries 2–7). To examine the effect of organic solvent, we employed a 1:1 mixture of

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• solubility of β-CD can be dramatically increased using a base, which occurs via the ionisation of the secondary hydroxy groups, near pH ≈12 (secondary hydroxy dissociation starts around ≈11.5–11.8 in water) [4][5]. In basic aqueous medium, the high reactivity and low water-miscibility of 1,2-propylene oxide

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• -assembly behavior in various solvents was investigated particularly in aqueous medium, due to the recently discovered hydrophilic properties of B21C7 crown macrocycle. An unexpected fluorescence quenching phenomenon was observed in the PDI-B21C7 macrocycle conjugate in chloroform. The detailed UV–vis

• absorption and fluorescence spectra of these PDI/NDI derivatives in different solvents as well as their morphologies were investigated. Keywords: aqueous medium; crown ether; macrocycle; perylene diimide derivative; self-assembly; Introduction Owing to their unique physicochemical properties, self

• ][31][32]. Nowadays, as the research in supramolecular chemistry is expanding into the aqueous realm, a systematic understanding of the interaction relationship of supramolecular self-assemblies and aqueous medium is becoming increasingly important [33][34][35][36]. As the first generation of

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

• the 6A,6B-ditosyl-β-CD prepared in reaction 1, see Supporting Information File 1, Figures S18–S19). In summary, the direct ditosylation in environmentally friendly aqueous medium affords the 6A,6C- and 6A,6D-ditosyl-β-CDs, from which the 6A,6C- and 6A,6D-diazides are obtained in overall 29% and 21

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• -phosphoribose obtained by acid hydrolysis of adenosine monophosphate (AMP, 26, Scheme 13). In the first step, AMP was hydrolyzed under action of a Dowex resin in an aqueous medium at 100 °C to give 5-phosphoribose isolated as the disodium salt 27 in 85% yield with a purity of 88%. Subsequent amminolysis was

• -Dihydronicotinamide riboside, NRH, may be subsequently oxidized into NR+ salts using activated charcoal [31], salts for which a pharmaceutically acceptable counter anion X− can be introduced when using an aqueous medium containing the corresponding ammonium salt NH4X. The oxidation may also be achieved with

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

• observed for the water-soluble complexes 1a and 2a. This is most probably due to the reduced stability of those catalysts in aqueous medium and additionally to their limited contact with the substrates, being in a different phase (organic layer), and in a process that resembles more to a “heterogeneous

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• insoluble in an aqueous medium. In batch recycling reactions, it was tested if the reused enzyme would be partially deactivated after several reaction cycles in the presence of the organic solvent. Therefore, the amount of enzyme was increased in order to reduce the reaction time and as a consequence to

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-a]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium

• Nadia Bouzayani,
• Jamil Kraїem,
• Sylvain Marque,
• Yakdhane Kacem,
• Abel Carlin-Sinclair,
• Jérôme Marrot and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2018, 14, 2923–2930, doi:10.3762/bjoc.14.271

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