Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• structural diversification of steroids by means of multicomponent reactions (MCRs) have significantly increased over the last decade. This review covers the most relevant strategies dealing with the use of steroidal substrates in MCRs, including the synthesis of steroidal heterocycles and macrocycles as well

• supramolecular chemistry applications. Keywords: conjugation; heterocycles; macrocycles; multicomponent reactions; steroids; Review 1 Introduction The utilization of multicomponent reactions (MCRs) [1] for the derivatization of biomolecules has continuously grown over the last years. These diversity-oriented

• promise for the future development of peptide pharmaceuticals. 5 Multicomponent synthesis of steroidal macrocycles and cages Since the beginning of this century, the field of macrocycle synthesis has witnessed the emergence of MCRs as effective ring closing procedures, including the cyclization of large

Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• , simple, room-temperature method for producing tetra-meso-substituted porphyrins with bulky substituents. Keywords: condensation; grinding; mechanochemistry; milling; porphyrin; sterically-hindered; Introduction Porphyrins and related macrocycles such as chlorins, corroles, and bacteriochlorins carry

Design of a double-decker coordination cage revisited to make new cages and exemplify ligand isomerism

• Sagarika Samantray,
• Sreenivasulu Bandi and
• Dillip K. Chand

Beilstein J. Org. Chem. 2019, 15, 1129–1140, doi:10.3762/bjoc.15.109

• : anion binding; double-decker cage; ligand isomerism; macrocycles; palladium; self-assembly; supramolecular; Introduction Coordination-driven self-assembly is a convenient strategy for the construction of supramolecules of desired dimensions via simple synthetic procedures. Well-defined metal–ligand

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

• Dong-Hao Li Bradley D. Smith Department of Chemistry and Biochemistry, University of Notre Dame, 236 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States 10.3762/bjoc.15.105 Abstract This review summarizes the supramolecular properties of tetralactam macrocycles that have parallel

• aromatic sidewalls and four NH residues directed into the macrocyclic cavity. These macrocycles are versatile hosts for a large number of different guest structures in water and organic solvents, and they are well-suited for a range of supramolecular applications. The macrocyclic cavity contains a mixture

• effect; macrocycles; rotaxane; supramolecular; Review 1. Introduction A large fraction of host–guest chemistry research uses macrocyclic compounds as the host molecules [1][2]. There are several reasons for this circumstance. Macrocycles are often relatively easy to synthesize and they have inherently

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• isotherm model. Keywords: adsorption; cucurbit[7]uril; electrospinning; macrocycles; methylene blue; nanofiber; Introduction Electrospinning is recognized as the most simple and versatile method to fabricate multifunctional nanofibers from the solution or melt of polymers, polymer/nanoparticle mixtures

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

• Angélica de Fátima S. Barreto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

• isocyanide-based multicomponent reactions in the synthesis of macrocycles containing a tetrazole nucleus [30]. The strategy was based on the use of α-isocyano-ω-carboxylic esters 71 via a microwave-mediated Ugi-azide reaction at the beginning of the synthesis and an intramolecular Ugi reaction of

• bifunctional compounds 74 at the end, allowing the obtention of the 16- to 20-membered tetrazolic macrocycles 75 in only five steps (Scheme 14). A similar approach was used shortly afterwards by the same research group in the synthesis of macrocyclic depsipeptides containing a tetrazole nucleus [31]. The

• intramolecular Passerini reaction was performed using bifunctional isocyanocarboxylate (Scheme 15a). Scheme 15b shows three of the 21 depsipeptides macrocycles synthesized by the authors in this study. Ethyl isocyanoacetate (13b) has also been successfully used as starting material to allow consecutive Ugi

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• stabilities by exhibiting a decomposition temperature up to 320 °C. In 2013, Severin and co-workers reported the mechanochemical synthesis of large macrocycles with borasiloxane and imine links using a ball mill (Figure 12). In a polycondensation reaction using diamines, 4-formylbenzeneboronic acid and t

• ester cages of type 22 [64]. Mechanochemical synthesis of borasiloxane-based macrocycles. Mechanochemical synthesis of 2-dimensional aromatic polyamides. Nitschke’s tetrahedral Fe(II) cage 25. Mechanochemical one-pot synthesis of the 22-component [Fe4(AD2)6]4− 26, 11-component [Fe2(BD2)3]2− 27 and 5

• thermodynamic control. Preferential formation of hexamer 33 under mechanochemical shaking via non-covalent interactions of peptide chains. Anion templated mechanochemical synthesis of macrocycles cycHC[n] by validating the concept of dynamic covalent chemistry. Hydrogen-bond-assisted [2 + 2]-cycloaddition

Solid-phase synthesis of biaryl bicyclic peptides containing a 3-aryltyrosine or a 4-arylphenylalanine moiety

• Iteng Ng-Choi,
• Àngel Oliveras,
• Lidia Feliu and
• Marta Planas

Beilstein J. Org. Chem. 2019, 15, 761–768, doi:10.3762/bjoc.15.72

• ; cross-coupling; cyclization; macrocycles; solid-phase synthesis; Introduction Monocyclic and bicyclic peptides are acquiring a relevant interest in current drug discovery. They display improved biological properties over their acyclic counterparts and, at the same time, they are suitable to modulate

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• ], thioether macrocycles [11], macrocyclic Schiff bases [12] or even poly(phthalaldehyde) polymers [13]; taking into account that few studies were carried out with modified OPA on position 3 or 4. This could probably be due to the fact that the synthesis of 4-substituted OPA was, to the best of our knowledge

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• much better understanding of complex biological systems [1]. Since the serendipitous discovery of crown ethers by Charles Pedersen in 1967 [2], there have been significant advances in the design and synthesis of sophisticated multidentate macrocycles with mixed-donor sites [3] and high selectivity

• ], respectively. The family of dibenzotetraaza[14]annulenes (abbreviated hereafter as DBTAAs) belong to a class of quadridentate Schiff base macrocycles that display exceptional stability toward light, oxygen and water [14]. Thanks to basic similarities in their structure and physicochemical properties, DBTAAs

• presence of alkali metal and ammonium ions. Sakata et al. reported the synthesis of peripherally functionalized DBTAAs with the two benzo-15-crown-5 scaffolds appended to the meso-benzoyl substituents [27]. Both crown ether-capped macrocycles in a form of free base and nickel(II) and cobalt(II) complexes

Selectivity in multiple multicomponent reactions: types and synthetic applications

• Ouldouz Ghashghaei,
• Francesca Seghetti and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2019, 15, 521–534, doi:10.3762/bjoc.15.46

• , symmetrical adducts or polymers; ii) structurally preorganized systems allowing the generation of macrocycles and iii) selective processes in which a determined combination arises in a sequential manner, either directly or indirectly, through functional group deprotection/generation. Stereoselectivity (where

• multicomponent macrocyclization strategy [18][20] (Scheme 4) constitutes a breakthrough in the field, providing a powerful synthetic tool to systematically design and prepare a variety of structures. The implementation of this approach goes beyond simple macrocycles, and was exploited to deliver macromulticycles

Design of indole- and MCR-based macrocycles as p53-MDM2 antagonists

• Constantinos G. Neochoritis,
• Maryam Kazemi Miraki,
• Eman M. M. Abdelraheem,
• Ewa Surmiak,
• Tryfon Zarganes-Tzitzikas,
• Beata Łabuzek,
• Tad A. Holak and
• Alexander Dömling

Beilstein J. Org. Chem. 2019, 15, 513–520, doi:10.3762/bjoc.15.45

• Modares University, P.O. Box 14155-4838, Tehran, Iran Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland 10.3762/bjoc.15.45 Abstract Macrocycles were designed to antagonize the protein–protein interaction p53-MDM2 based on the three-finger pharmacophore F19W23L25. The

• synthesis was accomplished by a rapid, one-pot synthesis of indole-based macrocycles based on Ugi macrocyclization. The reaction of 12 different α,ω-amino acids and different indole-3-carboxaldehyde derivatives afforded a unique library of macrocycles otherwise difficult to access. Screening of the library

• for p53-MDM2 inhibition by fluorescence polarization and 1H,15N HSQC NMR measurements confirm MDM2 binding. Keywords: 1H,15N HSQC NMR; indole; macrocycles; multicomponent; p53-MDM2; Ugi reaction; Introduction Macrocycles are the chemical entities that are consisting of a 12-membered or even bigger

LCST phase behavior of benzo-21-crown-7 with different alkyl chains

• Yan Deng,
• Xing Li,
• Qiao Zhang,
• Zheng Luo,
• Chengyou Han and
• Shengyi Dong

Beilstein J. Org. Chem. 2019, 15, 437–444, doi:10.3762/bjoc.15.38

• molecules-containing systems has been developed exhibiting LCST behavior and adjustable thermo-responsive properties. These include ionic liquids [27][28][29][30], macrocycles [31][32][33][34], and supramolecular pairs [26][35][36][37][38]. For example, the combination of macrocycles and supramolecular

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• . Compound B has a macrocycle composed of 4-amino acids, but it exhibited no necrotic activity. As seen in the structures of all the toxins depicted in Figure S15 (Supporting Information File 1), the macrocycles are in terminal positions; thus, having the macrocycle at the termini may be required for the

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• macrocycles was used for the synthesis of multiblock copolymers with random or sequence-controlled structure [66]. The ROMP is also suitable for the synthesis of bottle-brush block copolymers, in which linear or branched side chains are densely grafted to a linear backbone, being easily functionalized for

• approaches for fabricating symmetric and asymmetric telechelics and monochelics, macromonomers and macrocycles based on different olefin-metathesis techniques like CTA, ADMET, etc. A subsequent assembling of macroblocks into copolymers can be carried out by combining olefin metathesis with other reactions

First synthesis of cryptands with sucrose scaffold

• Patrycja Sokołowska,
• Michał Kowalski and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2019, 15, 210–217, doi:10.3762/bjoc.15.20

• ring, functional groups etc. Carbohydrates are especially useful platforms for macrocycles being able to recognize enantiomers. Special attention is directed to native and modified cyclodextrins, cyclic oligosaccharides, which have found wide application in many aspects of chemistry and industry [3][4

• structure. Up to date, only monosaccharides have been intensively used as chiral building blocks in the synthesis of such macrocycles. Less attention, however, has been paid to macrocycles with disaccharides (or oligosaccharides) being a part of the ring [6][7][8]. We have proposed to use sucrose (1) as a

• convenient chiral platform for such macrocycles [9][10]. Several of them, such as 5 (Figure 1), are able to differentiate enantiomers of α-phenylethylammonium salt [11][12]. Sucrose dimers containing two urea or thiourea units (6 or 7) are able to complex anions [13][14]. More complex derivatives with

A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts

• Daniel S. Müller,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2018, 14, 2999–3010, doi:10.3762/bjoc.14.279

• also studied the stereoretentive RCM reaction for the synthesis of Z- and E-configured macrocycles (e.g., 24) [14][15]. As predicted from the working model, bulky catalyst Ru-4 performed very well for the RCM reaction with Z-alkene 23, whereas the smaller catalyst Ru-9 performed best for E-alkene 25

• higher catalyst loading (10.0–12.5 mol %) [21]. Macrocyclic ring-closing metathesis (RCM) with (Z)-butene (Z-25) was also studied affording 14–21-membered macrocycles (e.g., 38) in good yield and high stereoretention (Scheme 6b). More recently Hoveyda disclosed his findings concerning the synthesis of Z

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• with Suzuki–Miyaura cross coupling in combination with metathesis (or vice-versa). Several cyclophanes, polycycles, macrocycles, spirocycles, stilbenes, biaryls, and heterocycles have been synthesized by employing a combination of Suzuki cross-coupling and metathesis. Various popular reactions such as

• and ease of handling of organoboron reagents [13][14][15][16][17] have propelled the growth of the SM cross coupling. A synergistic combination of these two elegant methods (i.e., SM coupling and metathesis) [18] was found to increase the synthetic efficiency of complex targets (e.g., macrocycles [19

• the corresponding epoxide 110. Unfortunately, generation of epoxide was not realized (Scheme 16). Macrocycles To develop new synthetic strategies to various cyclophanes, we conceived a sequential usage of the SM coupling and RCM as key steps [48][49]. In this context, the required dialdehyde 113 (80

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• Organische Chemie, Universität Münster, Corrensstrasse 40, 48149 Münster, Germany 10.3762/bjoc.14.217 Abstract Copper(I)-promoted "click" cyclization in the presence of TBTA afforded nucleoside macrocycles in very high yields (≈70%) without using protecting groups. To this end, dU and dC derivatives

• functionalized at the 5-position of the nucleobase with octadiynyl side chains and with azido groups at the 5’-position of the sugar moieties were synthesized. The macrocycles display freely accessible Watson–Crick recognition sites. The conformation of the 16-membered macrocycle was deduced from X-ray analysis

• and 1H,1H-NMR coupling constants. The sugar conformation (N vs S) was different in solution as compared to the solid state. Keywords: click cyclization; conformation; macrocycles; nucleosides; X-ray; Introduction The field of macrocycles was initiated by the work of Ruzicka and his structure

Non-metal-templated approaches to bis(borane) derivatives of macrocyclic dibridgehead diphosphines via alkene metathesis

• Tobias Fiedler,
• Michał Barbasiewicz,
• Michael Stollenz and
• John A. Gladysz

Beilstein J. Org. Chem. 2018, 14, 2354–2365, doi:10.3762/bjoc.14.211

• Scheme 1 that give thirty-three membered macrocycles (n = 30) [7]. However, none have so far been detected. Other types of crossed chain in/out isomer systems have in fact been realized [25][30]. As communicated earlier [28] and will be described more fully in a later paper, both isomers of 2·2BH3 are

Synthesis and post-functionalization of alternate-linked-meta-para-[2ⁿ.1ⁿ]thiacyclophanes

• Wout De Leger,
• Koen Adriaensen,
• Koen Robeyns,
• Luc Van Meervelt,
• Joice Thomas,
• Björn Meijers,
• Mario Smet and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2190–2197, doi:10.3762/bjoc.14.192

• , we report our method of choice to selectively synthesize 7. Purification of [3 + 3] adduct 7 was successful via precipitation (CHCl3/MeOH) in good yield (64%). Proposed mechanism and stability In Scheme 3 a reaction mechanism for the formation of the macrocycles is proposed. It is believed that after

• thermodynamically stable [2 + 2] macrocycle 6 (41%, see Figure S13, Supporting Information File 1). Due to the instability of the macrocycles, purification of the reaction mixtures via column chromatography (silica/alumina) or selective crystallization was difficult. Changing the biselectrophile precursor to

• similar conditions as reported by Cragg et al. [35]. The reaction in the presence of p-toluenesulfonic acid (0.05 equiv) led mainly to oligomerization, although in the 1H NMR spectrum traces of macrocycles 6 and 7 were observed (Scheme 5). Post-functionalization As the macrocycles are not stable in

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

• electrochemical operation of MIMs. Several excellent reviews on the use of TTF in other supramolecular systems such as macrocycles, cages, and receptor molecules are already available [15][16][17][18][19][20][21]. In this review, motifs of construction and working principles of TTF-based MIMs in the past and

• supramolecular chemistry [28] and for the construction of MIMs [29], the good π-donor properties of TTF are frequently used to template donor–acceptor complexes with π-electron deficient macrocycles. If TTF undergoes oxidation, the π-donating effect decreases, whereas the TTF2+ dication can be considered as a π

• 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

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• bis(benzylalkylammonium) axle [19], where the stereoselective formation of the pseudo[3]rotaxane with endo-alkyl orientation VIII was observed [19]. Calixarene macrocycles [22] have found numerous applications in several areas of supramolecular chemistry, such as (bio)molecular recognition [23] and

• catalysis [24]. The widespread use of the calixarene derivatives is due to their convenient synthesis and to their chemical and conformational versatility [25]. In fact, calixarene macrocycles present a conformational isomerism that in the case of calix[6]arenes gives rise to eight discrete conformations

• threading of calix[6]arene macrocycles in conformations different than the cone one has been rarely observed [17]. Interestingly, the assembling of interpenetrated structures in which the wheel adopts different conformational isomers, could pave the way to mechanomolecules which exhibit novel isomeric forms

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

• performed for the first time. It was found that the synthesized macrocycles form stable aggregates with hydrodynamic diameters between 150–200 nm and electrokinetic potentials about +40 to +60 mV in water solutions. Critical aggregation concentration (CAC) values were measured using a micelle method with

• pyrene and eosin Y as dye probes. The CAC values of tetraalkyl-substituted macrocycles 12a,b (5 µM for both) are significantly lower than those for dialkyl-substituted macrocycles 10a,b (790 and 160 µM, respectively). Premicellar aggregates of macrocycles 10a,b and 12a,b with the dye eosin Y were used

• for nucleotides sensing through a dye replacement procedure. It is unusual that disubstituted macrocycles 10a,b bind more effectively a less charged adenosine 5'-diphosphate (ADP) than adenosine 5'-triphosphate (ATP). A simple colorimetric method based on polydiacetylene vesicles decorated with 10b

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

• mechanically interlocked macrocycles. The flexible but strong mechanical bond between the interlocked macrocycles offers a unique opportunity for exploiting catenanes as molecular machines or new materials with unusual mechanical properties [1][2][3][4][5][6][7][8][9]. Over the years, different templates and

• ring-closing reactions to form the interlocked macrocycles have been developed, but the majority of the reported catenanes is limited to the Hopf link (i.e., the simplest [2]catenane with two crossings) [9]. Synthesis of other high-order catenanes with more interlocked macrocycles and/or more crossing

• points remain challenging and more general synthetic strategies to catenanes are yet to be realized [10][11][12]. A major challenge in [n]catenane synthesis is the precise spatiotemporal control of the covalent formation of the macrocycles and their mechanical interlocking. Otherwise, various topological