Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• irradiation as well as by host molecule (α-cyclodextrin) complexation [278]. Due to the high number of proton acceptor/donor sites, ureido-modified copolymers such as poly(allylamine-co-allylurea) are also becoming more and more important. The critical phase transition temperature can often be finely tuned

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

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• substrate with suitable binding sites for photochemical transformations. Cyclodextrin-based photocatalysis CDs represent a family of macrocyclic compounds in which the ᴅ-glucopyranose units are connected to each other via an α-1,4-glycosidic bond. The inside of a cyclodextrin is a hydrophobic cavity, and

• the outside possesses the polyhydroxy structure. This unique asymmetric barrel-shaped cavity allows them to combine with various guests. The driving forces for the formation of cyclodextrin-based supramolecular complexes are hydrophobic and van der Waals interactions between the cavity and the

• hydrophobic part of the guests. α-, β-, and γ-CDs are the most common macrocycles, consisting of 6, 7, and 8 ᴅ-glucopyranose residues, respectively. Due to the differences in the cavity size, each cyclodextrin has the ability to form a complex with a specific guest, and the binding force depends on the size

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

• to its functionalization with negatively charged sulfate groups. The binding behavior of dPGS to L-selectin has been thoroughly probed as dendrimer [26][27], conjugated to a polymer [28] or as amphiphilic adamantyl conjugates that are able to self-assemble on cyclodextrin vesicles [29]. Our group

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• aggregates is converted to an n-fold completive mixture. Alike the material presented later we do not start from the ensemble of constituents, but already from aggregates. Basilio and Parola demonstrated the pH-triggered 2-fold completive self-sorting of four components comprising β-cyclodextrin (4

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• study, we found that the reactivity depended more upon diffusion phenomena in the crystalline parts of the material than on the increase in the surface area of the CD particles resulting from grinding. Keywords: beta-cyclodextrin; chemoselectivity; grinding; mechanosynthesis; reactivity; Introduction

• characterized upon grinding over various grinding times, we carried out the synthesis of mono-6-O-(2-mesitylenesulfonyl)-β-cyclodextrin (β-CDMts, see Supporting Information File 1 for NMR spectra). Ground β-CD and MtsCl were placed in the jar and milled at 30 Hz and the conversion into the product was plotted

• %) and potassium hydroxide (90%) were purchased from Sigma-Aldrich. All chemicals were used without further purification. Preparation of β-CD samples Analogously as described in [14]. General procedure for the synthesis of mono-6-O-(2-mesitylenesulfonyl)-β-cyclodextrin β-CD (1500 mg, 1.32 mmol) and MtsCl

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• Alberto Rubin Pedrazzo Fabrizio Caldera Marco Zanetti Silvia Lucia Appleton Nilesh Kumar Dhakar Francesco Trotta Dipartimento di Chimica, Università degli Studi di Torino, Via Giuria 7, Torino 10125, Italy 10.3762/bjoc.16.127 Abstract Cyclodextrin nanosponges (CD-NS) are nanostructured

• , and rhodamine B) and the still reactive imidazoyl carbonyl group of the NS. Keywords: β-cyclodextrin; ball-milling; crosslinking; green chemistry; mechanochemistry; nanosponges; Introduction The research in the fields of nanomedicine and nanotechnology has nowadays become predominant

• . Polysaccharides and, among them, starch derivatives such as cyclodextrins (CD), have recently emerged as they are safe, of low cost and biodegradable. Cyclodextrin nanosponges (CD-NS) are crosslinked cyclodextrin polymers characterized by a nanosized three-dimensional network. The reactive hydroxy groups of CDs

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

• Margareta Sohora,
• Leo Mandić and
• Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

• Zagreb, Croatia 10.3762/bjoc.16.110 Abstract Stability constants for the inclusion complexes of cyclohexylphthalimide 2 and adamantylphthalimide 3 with β-cyclodextrin (β-CD) were determined by 1H NMR titration, K = 190 ± 50 M−1, and K = 2600 ± 600 M−1, respectively. Photochemical reactivity of the

• systems for the control of photoreactivity. Keywords: [3 + 2] cycloadditions; β-cyclodextrin; inclusion complexes; photochemistry; phthalimides; Introduction Cycloadditions are highly useful reactions in organic synthesis providing complex cyclic structures from easily available precursors [1][2]. Among

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• -cyclodextrin as the cocatalyst provide 196 in a good yield and excellent stereoselectivity (Scheme 61). In 2011, Hurvois and his group reported a stereoselective electrochemical total synthesis of the tetrahydroisoquinoline alkaloid (−)-crispine A (200) and its natural enantiomer [108]. The initial steps

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• ., β-cyclodextrin-benzimidazole2 (β-CD-BM2), were investigated at neutral and acidic pH conditions, respectively. Specifically, β-CD-BM2 first self-assembled into fan-shaped supramolecular self-assemblies with a hydrodynamic diameter of 163 nm at neutral pH, whereas they were further dissociated into

• varied morphology could inhibit cancer cell proliferation, indicating their potential application in the field of drug delivery. Keywords: β-cyclodextrin; controlled drug delivery; host–guest interaction; stimuli-responsive; supramolecular self-assemblies; Introduction Supramolecular self-assemblies

• stimuli-responsive supramolecular self-assemblies with regulated self-assembly morphologies due to their response to various external stimuli, such as temperature [12], light [13][14][15], redox [16][17][18], and pH [19][20]. In addition, β-cyclodextrin (β-CD), pillararene and cucurbituril have been

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

• Jason Yin Hei Man Ho Yu Au-Yeung Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China 10.3762/bjoc.15.177 Abstract A series of hetero [4]-, [5]- and [6]rotaxanes containing both cucurbit[6]uril (CB[6]) and γ-cyclodextrin (γ-CD) as the macrocyclic components

• respect to the orthogonal plane of the axle, only one stereoisomer of the [6]rotaxane was obtained. Keywords: cucurbit[6]uril; cyclodextrin; macrocycles; mechanostereoisomer; rotaxane; Introduction Cyclodextrins (CDs) are macrocycles composed of glucoses linked via α-1,4-glycosidic bonds. CDs of six (α

• interlocking at one of the tetra(ethylene glycol) moieties, possibly as a result of the stabilizing interactions between the γ-CD and CB[6]. Indeed, due to the strong interactions between CB[6] and cyclodextrin, it has been reported that CB[6] can dissemble a [3]pseudorotaxane consisting of two linear axles

Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

• Stiliyana Pereva,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163

• .15.163 Abstract Cyclodextrins (CDs) are native host systems with inherent ability to form inclusion complexes with various molecular entities, mostly hydrophobic substances. Host cyclodextrins are accommodative to water molecules as well and contain water in the native state. For β-cyclodextrin (β-CD

• thermodynamic characteristics of β-CD hydration compare with those of its smaller α-cyclodextrin (α-CD) counterpart? In this study, we address these questions by employing a combination of experimental (DSC/TG) and theoretical (DFT) approaches. Keywords: β-cyclodextrin; DFT calculations; DSC/TG experiments

• evaluated at the M062X/6-311++G(d,p)//M062X/6-31G(d,p) level of theory (Supporting Information File 1, Table S1). As a general trend, it was observed that expanding the intramolecular hydrogen bond network upon each H2O addition (comprising the water–water and water–cyclodextrin interactions) enhances the

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

• Laszlo Jicsinszky Federica Calsolaro Katia Martina Fabio Bucciol Maela Manzoli Giancarlo Cravotto Dipartimento di Scienza e Tecnologia del Farmaco, University of Turin, via P. Giuria 9, 10125 Turin, Italy 10.3762/bjoc.15.145 Abstract This work presents a proof of concept for a green cyclodextrin

• have different complexation properties to those of their classically prepared analogues. Keywords: crosslinked cyclodextrin polymers; (2-hydroxy)propylcyclodextrin; mechanochemistry; nucleophile reaction; planetary ball mill; solventless synthesis; Introduction The derivatisation of natural

• cyclodextrins (CDs, cyclic α(1->4)-linked glucopyranosides) is always a difficult task, particularly when the attached moiety is prone to further derivatisation. In many cases, statistical (random) substitution results in essential changes in the hydrogen bonding systems of the cyclodextrin hydroxy rims, and is

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• of gold nanorods (AuNR) by thiolated cyclodextrin (CD) host molecules. As a result of the complete removal of the precursor capping agent cetyltrimethylammonium bromide (CTAB) by a tetraethylene glycol derivative, competitive binding to the host cavity was prevented, and reversible, light-responsive

• 20-fold higher binding constant to β-CD (6.5 × 104 M−1) [32] than unmodified azobenzenes (2.5 × 103 M−1) [33]. Therefore, the competitive binding of CTAB to β-CD has been applied previously, e.g., in sensing applications [34] or to enhance the water solubility of a cyclodextrin polymer [35]. On

• AuNR are functionalized selectively in a two-step ligand exchange reaction. The ends are capped with per-6-thio-β-cyclodextrin (tCD) and CTAB is removed from the remaining surface by monothiolated tetraethylene glycol (tTEG) enabling reversible host–guest chemistry. The addition of a divalent AAP

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• and photoactivity annihilation. The complexation behavior between some of abovementioned luminescent dyes and cyclodextrin (CD) derivatives, especially β-CD, also has been investigated in the literature [30][31][32]. β-CD exhibits relatively weak binding affinities on the magnitude (or less than) of

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• , Czech Republic 10.3762/bjoc.15.80 Abstract The preparation of new organocatalysts for asymmetric syntheses has become a key stage of enantioselective catalysis. In particular, the development of new cyclodextrin (CD)-based organocatalysts allowed to perform enantioselective reactions in water and to

• ; cinchona alkaloids; CuAAC click reaction; cyclodextrin; organocatalysts; Introduction Cyclodextrins (CDs) [1], cyclic oligosaccharides consisting of α-D-glucopyranoside units, and their derivatives are widely used in many industrial and research areas for their ability to form supramolecular inclusion

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

• Gabor Benkovics Mihaly Balint Eva Fenyvesi Erzsebet Varga Szabolcs Beni Konstantina Yannakopoulou Milo Malanga CycloLab, Cyclodextrin Research and Development Laboratory Ltd., llatos út 7, Budapest, H-1097, Hungary Department of Pharmacognosy, Semmelweis University, Budapest, H-1085 Üllői út 26

• - and 6A-monoazido-6X-monotosyl-β-CD were prepared in one or two steps and purified in multigram scale thus opening the way towards further selective and orthogonal functionalizations of β-CD hosts. Keywords: azido-tosyl-cyclodextrin; diazido-cyclodextrin; hetero-difunctionalization; homo

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

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

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• addition, by subjecting the same materials to chemical post-modification, it is possible to introduce further groups able to provide responsivity to external stimuli. We have recently succeeded in obtaining NSs based on polyamino-cyclodextrins (ACDNs) [15] as well as mixed cyclodextrin–calixarene

• copolymers (CyCaNSs) [16][17][18], which showed pH-dependent sequestration abilities towards different model organic substrates. The latter NSs were easily synthesized by means of a CuAAC-type reaction [19][20][21] between a heptakisazido-β-cyclodextrin and a tetrakis(propargyloxy)calix[4]arene derivative

• with CyCaNSs. This fact was explained assuming that a diazidoalkane is a less effective reticulating agent than a heptakisazido-β-cyclodextrin, simply because of the lesser number of reactive azide groups present. Hence, we reasoned that the polymer network formation process could have been improved by

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

• (Figure 1c) through host–guest interactions [61]. Chung and co-workers used a PEG-tethered adamantyl ligand for various metathesis reactions in water and DCM [62]. The authors showed that the catalyst can be easily removed by generating a host–guest complex between silica-grafted β-cyclodextrin and the

• through host–guest interaction with silica-gel-supported β-cyclodextrin. Selection of artificial metathases reported by Ward and co-workers (ArM 1 based on biotin–(strept)avidin technology and ArM 2 based on dative anchoring to hCAII). Artificial metathase based on covalent anchoring approach. α

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• supramolecular fiber materials composed of cyclodextrin (CD)–fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. We believe such a concept could be expanded to diverse host–guest complexes

• , opening up supramolecular solid materials science and engineering. Keywords: cyclodextrin; electrospinning; fullerene; nanofiber; supramolecular complex; Introduction Fiber is a fundamental material that constitutes a variety of everyday items and supports the maintenance of life [1][2][3]. In the field

• gemini surfactants [7], diphenylalanine [8], cyclodextrin (CD)/CD derivatives [9][10][11][12], heteroditopic monomers [13], and self-assembling oligopeptides [14] have been successfully electrospun to produce continuous fibers. Among these molecules, CD is a unique compound that can form fibers despite

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

• Iveta Tichá,
• Gábor Benkovics,
• Milo Malanga and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

• Iveta Ticha Gabor Benkovics Milo Malanga Jindrich Jindrich Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic CycloLab, Cyclodextrin R&D Ltd., Illatos út 7, H-1097 Budapest, Hungary 10.3762/bjoc.14.261 Abstract The synthesis of

• batch-to-batch reproducible cyclodextrin (CD) derivatives often requires functionalization at specific positions of the CD skeleton. However, the regioselective preparation of this type of CD derivatives remains a challenge in synthetic chemistry. Thus, the present study aimed to prepare all positional

• findings indicate, (i) the versatility of selectively modified azido and mesitylene CD skeletons in preparing new types of α-CD derivatives and (ii) the potential of using resolved α-CD pseudoenantiomers in other research fields such as organocatalysis. Keywords: diazido-alpha-cyclodextrin

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

• Matthew B. Calvert,
• Varsha R. Jumde and
• Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

• FmlH (compounds 8 and 9) and Pseudomonas aeruginosa LecA (compounds 10–12). Mannosides and fucosides as inhibitors of P. aeruginosa LecB. β-Cyclodextrin-based antitoxin 19 against S. aureus α-hemolysin and the decavalent Shiga toxin inhibitors STARFISH (20) and DAISY (21). The mechanism of quorum

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

• , extended π-surfaces [64] of TTF derivatives can have a stabilizing effect upon complexation. TTF (1) also forms inclusion complexes with neutral host molecules such as cyclodextrins (Figure 6). This complexation is mainly driven by the hydrophobic effect. α-Cyclodextrin (6) molecules encapsulate the

• of these bistable donor–acceptor rotaxanes were subsequently underpinned by several quantum mechanical studies [77][78][79]. The concept of TTF-based switchable rotaxanes was also extended to rotaxanes with other macrocycles. In Figure 13, the bistable [2]rotaxane 15 is shown with an α-cyclodextrin

• first TTF-based rotaxane 13. A redox-switchable bistable molecular shuttle 14. The redox-switchable cyclodextrin-based rotaxane 15. The redox-switchable non-ionic rotaxane 16 with a pyromellitic diimide macrocycle. The redox-switchable TTF rotaxane 17 based on a crown/ammonium binding motif. Structure

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

• infrared spectrum of the functionalized graphene-family materials; thus, XPS should be regarded as a supporting analysis, as many researchers have demonstrated (see, e.g., [21][28][29]). Interestingly, for a reaction that includes water molecules and a hydroxy group-bearing compound (β-cyclodextrin) [25

• presented analyses the RGO surface can be assumed to include the adsorbed β-cyclodextrin (RGO has been obtained via a reduction of GO using sodium borohydride). Finally, there is a misunderstanding regarding the structure of the product bearing the amide moiety, as the lack of evidence for the formation of

• [40], it was not clear how the ester bond between RGO and hydroxypropyl-β-cyclodextrin would form, as the changes observed in the infrared spectra cannot be regarded as direct evidence for the formation of such linkages (IR analyses: C=O for carboxyl of GO: 1745 cm−1, C=O coming from ester bond stated

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• favorably interact with these units could be introduced to give higher-order catenanes with multiple interlocked rings. As a preliminary study of high-order [n]catenane assembly using this approach, CBAAC of BP-N3 and DN-CC was repeated in the presence of 10 equivalents of β-cyclodextrin (β-CD), which is