Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• with a known congener, nomimicin A (4), from Actinomadura sp. AKA43. Compounds 1 and 2 are new members of the spirotetronate-class antibiotics, characterized by a macrocyclic structure containing a trans-decalin unit and a tetronic acid moiety spiro-linked with a cyclohexene ring. To date, more than

• 100 compounds [21][22], including tetrocarcin [23] and kijanimicin [24], are known within the spirotetronate class. Of these, nomimicins A–C (4, 1, and 2) are featured by the smallest macrocyclic ring and highly oxygenated dehydrodecalin moiety. Spirotetronates are known to be constructed by the

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• )-glucosamine macrocyclic compounds [265]. The iterative glycosylation of N-Phth protected 2-deoxy-2-aminothioglycosides allowed for the combinatorial synthesis of short oligoglucosamines having β(1–6) and/or β(1–4)-linkages [263]. Automated solution-phase synthesis of β(1–6)-glucosamine oligosaccharides

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• , several products were submitted to a subsequent metathesis mediated by Grubbs-II catalyst and a further palladium-catalyzed C=C reduction and DG-removal process, from which the desired macrocyclic peptides were obtained in good to excellent yields (Scheme 35C). Recently, again Ackermann and co-workers

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• induced distortion of the macrocyclic core. Due to their relatively large size and high electronegativity, halogens induce a conformational distortion of the porphyrin core that is significant compared to those induced by other substitution groups. As recently illustrated in a review by Kielmann and Senge

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• %; 85% ee), but the reaction times were very short (Scheme 7) [41]. In 2011, the groups of Hayashi and Chujo studied Pd complexes of diphosphacrown ethers [42]. The macrocyclic Pd complex PdL5 in combination with AgSbF6 or AgOTf was tested for the addition reaction of various arylboronic acids to 2

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

• electron-rich pyrazolylamine led to the formation of intermediate A. Simultaneously, intermediate B (condensation of arylgyoxal and primary amine 32b undergoes C=N addition with intermediate A. Intramolecular cyclization of C yields a macrocyclic intermediate D which is followed by p-TsOH-promoted ring

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• mediated by commercially available Ru homogeneous catalysts [148]. The process afforded C16 to C44 mixtures of macrocyclic oligobutadienes with up to 98% selectivity at moderate conversions (59–88%) using first-generation Ru complexes bearing a tricyclohexylphosphine (PCy3) ligand, mild reaction

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• nucleophilic esterification of potassium 1-(N-benzyloxycarbonylamino)alkylphosphonates 172 with alkyl halides in the presence of 18-crown-6. They also prepared a phosphonodepsidipeptide 174 with ethyl chloroacetate (173) as an electrophile (Scheme 33) [53]. The macrocyclic peptidyl phosphonodepsipeptide 180

• was designed on the basis of the acyclic conformational analog bound to the aspartic protease penicillopepsin. Dimethyl N-Cbz-1-amino-2-(naphthalen-2-yl)ethylphosphonate 176 was first prepared from 7-bromo-3,4-dihydronaphthalen-1(2H)-one (175) and further transformed to the macrocyclic peptidyl

• phosphonic monomethyl ester 177. The latter compound was alkylated with methyl 3-phenyl-2-trifluoromethanesulfonyloxypropanoate (178) to produce the macrocyclic peptidyl phosphonodepsipeptide 179, which was selectively hydrolyzed with TMSBr and treated with Dowex-Na+ to afford the macrocyclic peptidyl

Au(III) complexes with tetradentate-cyclam-based ligands

• Ann Christin Reiersølmoen,
• Thomas N. Solvi and
• Anne Fiksdahl

Beilstein J. Org. Chem. 2021, 17, 186–192, doi:10.3762/bjoc.17.18

• binding properties [25] and reactions with bovine serum albumin [27]. Cyclam is known as a tetraamino-macrocyclic ligand, which binds strongly to give complexes with many transition metal cations. While catalytic applications of square planar cyclam complexes are reported for metals, such as Ni [30][31

• macrocyclic byproduct (14%) was formed by condensation of three units of diamine A and malonyl dichloride. To inhibit the formation of the trimer, we decided to prepare the cyclams in an indirect way. In fact, increased yields of cyclam derivative 2a (68% yield over three steps) were obtained by malonyl

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

• with various macrocyclic hosts as well as on the role of macrocyclic-hosts-assisted hybrid materials in energy transfer. To keep the clarity of this review, the macrocycles are categorized into the most commonly used supramolecular hosts, including crown ethers, cyclodextrins, cucurbiturils

• advantages of the macrocycles in photocatalysis including: i) substrate selectivity, ii) controllability of the rate of photochemical reactions, iii) the close proximity to substrates in a confined space, iv) the generation of a stabilized high-energy transition state, and v) macrocyclic-cavity-size

• via photophysical analyses is relatively important. Hence, this review aims to summarize the photochemical transformation and catalytic reactivity of different guests within the various macrocyclic hosts of various sizes and shapes based on molecular recognition as well as the role of macrocyclic-host

The fluorescence of a mercury probe based on osthol

• Guangyan Luo,
• Zhishu Zeng,
• Lin Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

• Guangyan Luo Zhishu Zeng Lin Zhang Zhu Tao Qianjun Zhang Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.17.3 Abstract The ability of osthol (OST) to recognize mercury ions in aqueous solution was studied using

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• insulin Schmuck and co-workers reported a supramolecular ensemble in combination of a pyrene-tagged amphiphilic peptide beacon (6) and a macrocyclic host (cucurbit[8]uril, CB[8]) for ratiometric fluorescent detection of amino acid derivatives, specific peptides, and proteins in aqueous media (Figure 6

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• architectures and chemical topology [12][13][14][15][16][17][18][19][20][21][22][23]. Seeking new systems to produce pseudorotaxanes is currently considered a “hot topic” in supramolecular chemistry. As a new class of supramolecular macrocyclic hosts, pillararenes have received extensive attention in recent

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• made towards switchable macrocyclic receptors, in which crown ethers are functionalized with a stimuli-responsive unit [14][15]. These studies were mainly motivated by a biomimetic approach and included examples such as crown ethers incorporating photo-responsive azobenzene [15][16] or redox-active

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• Zhishu Zeng Jun Xie Guangyan Luo Zhu Tao Qianjun Zhang Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, No. 2708, South Section of Huaxi Avenue, Huaxi, Guiyang 550025, China 10.3762/bjoc.16.194 Abstract In this study, we investigated the host

• the inclusion compound with Q[8]. Keywords: cucurbit[8]uril; host–guest interaction; inclusion complex; oroxin A; properties; Introduction Cucurbit[n]urils (Q[n]s) are a family of macrocyclic cage compounds synthesized by the condensation of glycoluril and formaldehyde in a strong acidic solution [1

Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

• Elizabeth A. Margolis,
• Rebecca J. Keyes,
• Stephen D. Lockey IV and
• Edward E. Fenlon

Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192

• molecular knots. The modular second-generation approach to small trefoil knots described herein involves electrostatic interactions between an electron-rich bis-macrocyclic host compound and electron-deficient guests in the threading step. The bis-macrocyclic host was synthesized in eight steps and 6.6

• ]. Herein the synthesis of a unique bis-macrocyclic host 1 is described (Figure 1). Host 1 was designed to be a second-generation building block in the thread–link–cut (TLC) approach to molecular knots [13]. The two 25-atom macrocycles are electron-rich and complementary to the electron-deficient guests bis

• ), whereas host 1 and guest 3 would lead to a 75 backbone-atom trefoil (and unknotted macrocycle). Results and Discussion The synthesis of bis-macrocyclic host 1 began by breaking the symmetry of naphthalene-1,5-diol (4) by alkylation of one of the alcohols with 2-azidoethyl mesylate to yield azide 5 in 27

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• that would allow the analyte to become protonated. In order to incorporate both functional parts of a carboxylate, a macrocyclic receptor architecture is desirable. By using a cyclic structure, it is possible to accommodate a solvophobic environment alongside polar functional groups. The benefits of

• positions 8 of the carbazole, using, e.g., amide bonds. Anion receptors containing carbazole and amide functionalities were investigated in numerous works [6][7][8][9]. In some cases, these functionalities were incorporated into macrocyclic systems, thereby offering valuable insight for design criteria. For

• example, a carbazole-urea macrocycle was reported previously [10], however, the binding of anions occurred outside the receptor due to modest dimensions of the macrocyclic cavity. Using click-chemistry, a carbazole-triazole macrocycle, “tricarb”, was prepared that showed the ability to form non-covalent

Five-component, one-pot synthesis of an electroactive rotaxane comprising a bisferrocene macrocycle

• Natalie Lagesse,
• Luca Pisciottani,
• Maxime Douarre,
• Pascale Godard,
• Brice Kauffmann,
• Vicente Martí-Centelles and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2020, 16, 1564–1571, doi:10.3762/bjoc.16.128

• synthesis of macrocycle 2 was carried out using N,N'-dihexyl-1,4-butanediamide as the template, as represented in Figure 2. While the formation of some macrocyclic product was identified by 1H NMR and MS, it could not be completely separated from impurities (<29% yield after chromatographic purification

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• presence of PhSSPh, the new isomer 73 could also be converted to the desired (E,E)-isomer 71. In the total synthesis of the macrocyclic antibiotic antitumor agent (+)-hitachimycin, Smith used a disulfide-catalyzed isomerization [32] to synthesize the intermediate 75 with an E-configuration, which was

[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

• the macrocyclic host affected the stereochemistry of the reaction. Moreover, we studied photodecarboxylation reactions initiated by the phthalimide chromophore [17][18][19] and applied them in cyclizations with memory of chirality [20] and diastereoselective peptide cyclizations [21

Anthelmintic drug discovery: target identification, screening methods and the role of open science

• Frederick A. Partridge,
• Ruth Forman,
• Carole J. R. Bataille,
• Graham M. Wynne,
• Marina Nick,
• Angela J. Russell,
• Kathryn J. Else and
• David B. Sattelle

Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105

• cattle treated annually is hundreds of millions [1]. Treatment of horses, other equids, and companion animals is also a major use of anthelmintics. Anthelmintic drug discovery has been a continued emphasis in the animal health industry, driven by the spread of resistance to the macrocyclic lactones [2

• macrocyclic lactone is an effective microfilaricide but does not kill the adult nematodes. Ivermectin must therefore be administered annually or twice-annually for many years to eliminate the parasite in the population. Progress has been impressive: onchocerciasis has been largely controlled as a public

• action of anthelmintic compounds, since it has been recognised that we do not fully understand how many anthelmintics work – for example the concentrations of macrocyclic lactones that paralyse worms in vitro are much greater than the concentration achieved by effective doses in vivo [147]. Several

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• Xiaodong Zhang Jun Xie Zhiling Xu Zhu Tao Qianjun Zhang Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.16.9 Abstract The host–guest interactions between baicalein (BALE) and cucurbit[8]uril (Q[8]) and the

• , baicalein contains three phenolic hydroxy groups, which are easily oxidized to the quinone derivative and appear green, therefore, it has limited use in pharmaceuticals on account of its poor aqueous solubility and stability [31]. The cucurbit[n]urils (Q[n]s n = 5–8, 10, …) are macrocyclic hosts with a

• hydrophobic rigid cavity [32] (Figure 1). cucurbit[n]urils have a unique combination of properties including rigid highly symmetric structures, relatively large hydrophobic cavities and high thermal and chemical stability [33][34]. Cucurbit[n]urils are a type of macrocyclic drug carrier similar to macrocyclic

Understanding the role of active site residues in CotB2 catalysis using a cluster model

• Keren Raz,
• Ronja Driller,
• Thomas Brück,
• Bernhard Loll and
• Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

• different cellular compartments [1][2]. More specifically, the enigmatic class of terpene cyclases is responsible for converting linear aliphatic oligoprenyl diphosphates into various chemically complex macrocyclic products. The resulting terpene scaffolds and their functionalized terpenoid analogues

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• their isomerization properties [3][4]. Also, the incorporation of AB units into cyclic [5] or macrocyclic structures can control the switching, depending, i.a., on symmetry and ring strain [6][7][8][9]. By combining these approaches, half-lives can be tuned from milliseconds to years. The incorporation