Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• coronavirus vaccine chitosan–saponin coatings have been developed to study its immunogenic potential [32]. A complexation between saponin and cyclodextrins (native or derivative) is possible [33], and the resulting release kinetics is appropriate for the creation of new saponin-based drugs [34]. Their

• potential uses can be either for oral delivery targeting intestine [33] or for an anti-skin cancer treatment [35], for example. This complexation step is also interesting for the synthesis of molecular imprinted polymers containing cyclodextrin [36]. In previous works, we have produced crosslinked

• sheet-like structures observed being those macrostructures modified by water swelling and crushing after drying. Saponins, at a molecular level, probably confer an additional microporosity to the matrix, permitting the cyclodextrin moieties to be more available for complexation with phenolphthalein or

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• ingredients (APIs) is necessary to render them bioavailable. This study addresses the poor solubility of two potent steroid hormones, 17β-estradiol (BES) and progesterone (PRO), via their complexation with two water-soluble native cyclodextrins (CDs) namely β-CD and γ-CD. The hydrated inclusion complexes β

• : cyclodextrin; complexation; 17β-estradiol; progesterone; solubility; X-ray diffraction; Introduction The insolubility of active pharmaceutical ingredients (APIs) and other bioactive compounds in aqueous media and the associated challenges for effective drug delivery are well known to have beleaguered the

• pharmaceutical industry for many decades. However, the complexation of APIs with cyclodextrins (cyclic oligosaccharides) resulting in the formation of inclusion complexes, has proven to be a versatile technology for overcoming not only the poor aqueous solubility of APIs, but also unfavourable properties such as

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• hydrophobic cavity inside the molecule, while all hydrophilic hydroxy groups are arranged outside the cavity. This feature determines the main practical application of CDs as supramolecular hosts for host–guest interaction. Due to their low cost, low toxicity, and good complexation ability, they are

• frequently used in pharmaceutical, food, and chemical industries, agriculture, and environmental engineering [1]. They possess many hydroxy groups and are suitable for further chemical transformations that could alter their complexation ability [2]. Every glucose unit in CDs bears three hydroxy groups, i.e

• water [4]. The complexation of organic molecules by CDs in nonpolar media has not been widely studied yet, but in several cases, such results have been achieved [5][6]. Another interesting type of CD transformation is a connection of two CD molecules by some spacer via covalent bonds. Many such "dimers

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• hydroxy groups pointing towards the sides [1]. This makes the ‘hole’ in the donut a lipophilic cavity that in water can form complexes with small hydrophobic molecules [2] driven by the entropy increase by expulsion of water [3]. Compound 1 has a wide range of applications where the complexation of

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• ) Host–guest motif in the X-ray structure of 4c·HCl·3.5MeOH (guest molecule is shown in “spacefill” representation). (e) Hirshfeld surface of the TAAD cation in 4a·HCl·H2O·MeOH. (e) Hirshfeld surface of the TAAD cation in 4c·HCl·3.5MeOH. (a) Dynamic processes in TAADs 4 and complexation with ROH. (b

• subsequent complexation with phenylboronic acid. Quaternization of TAADs 4c, 4e, 6a, and 8a followed by deprotection of N-Boc groups. DFT calculated binding energies for the guest–host complexes ROH@4. Supporting Information Supporting Information File 277: Experimental procedures, NMR spectra, infrared

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• various organic molecules have been described so far. It was proved that the complexation of volatile organic compounds, such as aldehydes, into the CD’s cavity reduces the volatility and increases the solubility and bioavailability of these compounds [5][6][7][8][9][10][11][12][13][14]. The release of

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• transduce mechanical energy to the mechanophores. Typically, polymers were the force transmission medium of choice, but in a recent study, Potrzebowski, Szumna, and co-workers have shown that molecular capsules can behave as stress-sensitive units [65]. The authors demonstrated the effective complexation of

• the covalent capsule 5 (made from resorcinarene caps connected by four dihydrazone units of ʟ-cysteine) with C60 and C70 fullerenes upon neat ball milling in a planetary ball mill (Figure 6). The mechanochemical complexation is remarkable since the porous capsule does not possess large enough openings

• . Mechanochemical solid-state complexation of organic capsule 5 with fullerenes C70 in a planetary ball mill. Figure 6 was adapted from [65], H. Jędrzejewska et al., “Porous Molecular Capsules as Non- Polymeric Transducers of Mechanical Forces to Mechanophores”, Chem. Eur. J., with permission from John Wiley and

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• long-run experiment, after seven days of continuous reaction 0.42 mg of nickel (25% of the 1.66 mg initially complexed, see Figure 5) leached into the reaction solution. However, performing another round of complexation with NiCl2∙glyme did not restore the original activity of the catalyst in the

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• reactions and denitrogenative annulation according to Roy et al. [11]. Copper-catalyzed azide–alkyne cycloadditions are initiated via the (dual) complexation of the alkyne, whereas denitrogenative annulation on 1,2,3,4-tetrazoles is assumed to start via complexation of the open-form azide 18 (see Scheme 4

• confirmed via single crystal X-ray crystallography. Several other byproducts, such as the bistriazolo product were isolated (see Supporting Information File 1). The obtained triazoloquinoxaline and TIQ products are promising ligands for complexation with different metals. The formation of organometallic

• especially used as CO2 reduction catalysts [38][39][40] and noninvasive imaging probes [12][41]; examples for the application in organic light-emitting diodes [35] and as photoactive CO-releasing molecule [42][43] have been reported as well. For the complexation experiments, compounds with three different

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• –base interaction mechanisms Chemical essence of Lewis acid–base interaction All the above discussed fluorescent materials share the common characteristics of Lewis basicity. Therefore, the changes in band gaps and colors of the donor materials is essentially attributed to a Lewis acid–base complexation

A trustworthy mechanochemical route to isocyanides

• Francesco Basoccu,
• Federico Cuccu,
• Federico Casti,
• Rita Mocci,
• Claudia Fattuoni and
• Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 732–737, doi:10.3762/bjoc.18.73

• , they are often used in heterocycles formation [8][9], multicomponent strategies [10][11], polymers production [12][13], and metal complexation [14][15]. The molecular structure is composed of an N–C planar triple bond where the nitrogen atom assumes a positive charge due to the fourth bond with a

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• Prodip Howlader Michael Schmittel Center of Micro- and Nanochemistry and (Bio)Technology, Universität Siegen, Organische Chemie I, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany 10.3762/bjoc.18.62 Abstract Supramolecular catalysis is reviewed with an eye on heteroleptic aggregates/complexation

• chemistry and information science. Keywords: heteroleptic complexation; information science; supramolecular catalysis; switching catalysis; systems chemistry; Introduction Supramolecular catalysis [1][2][3] for most chemists is associated with a catalytically active capsule providing either activating

• Switchable catalysis due to reversible assembly/disassembly Toggling between intra- and intermolecular complexation in nanoswitches Review Catalysis using heteroleptic discrete supramolecular architectures In its early years, supramolecular chemistry mainly focused on host–guest interactions, primarily on

Synthesis of a new water-soluble hexacarboxylated tribenzotriquinacene derivative and its competitive host–guest interaction for drug delivery

• Man-Ping Li,
• Nan Yang and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2022, 18, 539–548, doi:10.3762/bjoc.18.56

• synthesized compounds were fully characterized by 1H and 13C NMR spectroscopy and mass spectrometry (see Supporting Information File 1) and the data were found to be consistent with the proposed structures. Host–guest complexation of TBTQ-CB6 with dimethyl viologen (MV). The host–guest complexation between

• -rich cavity of TBTQ-CB6 [32]. In addition, the proton resonances became broadened caused by the complexation dynamics, indicating the successful host–guest complexation between TBTQ-CB6 and MV. Subsequently, the association stoichiometry of the complex was studied by the Job plot method using

• association constant was determined to be Ka = (7.67 ± 0.34) × 104 M−1 by nonlinear curve fitting [33] (Figure 1d). Host–guest complexation of TBTQ-CB6 with doxorubicin (DOX). The host–guest complexation between TBTQ-CB6 and DOX was studied by methods similar to those used for TBTQ-CB6 and MV. The 1H NMR

Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• -derived bisisothiocyanate fragments 5e,f afforded the desired hetero-combination macrocycles M7–M12 without additional difficulties. It should be noted that the incorporation of CF3 groups on the aryl moieties was to increase the acidity of thiourea so as to provide better hydrogen-bonding complexation

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

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

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• were significantly increased with respect to G concentrations and no considerable changes were observed when further increasing the G concentration (1.2 equiv). The above results corroborated that the free rotation of m-TPEWP5 rings was arrested during the complexation with G, thus further leads to the

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• clearly shown that the complex of Co-N-heterocyclic ligand exhibits a higher activity. Sonogashira cross-coupling reactions were also reported by making use of a heterogeneous, efficient and green cobalt catalyst obtained through complexation of cobalt with methyl salicylate-functionalized chitosan fibres

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• constants for 1:1 complexation between the host 4 and the guest cations were calculated by Equation 1 [47], where Ka is the association constant of the host–guest interaction, while ΔI is the change in the fluorescence intensity of the host upon gradual addition of the guest, and Δa refers to the different

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• complexation. NH (amide) protons of the ligands located at 8.30–7.65 ppm were not detected in the metallic structure spectra. Signals in the ranges of 5.84–5.64 and 4.40–4.17 ppm, corresponding to H5 and H6 protons, respectively, were shifted to 5.44 (H5) and 4.19 (H6) ppm for L1-Ni, and to 5.56–5.48 and 4.29

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• stereoselective N-glycosylation. We hypothesize that because of the Lewis acid character, ZrCl4 could most likely form a precomplex with the sulfur atom of the oxathiolane ring, as in IV. The presence of the chiral ʟ-menthyl ester auxiliary function assists the complexation with ZrCl4 in a specific orientation

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• with diverse biological activities [17]. The key step first involved the rhodium carbenoid-mediated OH insertion/Claisen rearrangement following complexation of diazoester 56 and allylic alcohol 57 to produce intermediate 58 (Figure 13). Addition of BF3·OEt2 to the reaction mixture then catalyzed the α

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• activity, while for the wildtype no GGPP conversion is observed. These findings will assist in future protein engineering for improved activity and functional switches in other microbial terpene synthases. Highly conserved residues in the active site of SdS for Mg2+ complexation, substrate recognition and

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• enantioselectivity, but the catalyst itself accommodates the anion by adopting a helical conformation upon complexation (Scheme 18a) [84][85][86]. Initial studies proved these systems highly effective for the enantioselective Reissert reaction of quinolines with silyl ketene acetals [22], which could be later

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

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123