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

• association constant up to (2.1 ± 0.3) × 104 M−1. Meanwhile, this macrocycle showed no obvious or only slight enhancement of the fluorescence intensity with selected anions. Keywords: amidobenzene-containing macrocycle; hemicucurbituril; host–guest interaction; macrocycle; modification; Introduction

Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes

• Nicolai Wippert,
• Martin Nieger,
• Claudine Herlan,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2021, 17, 2773–2780, doi:10.3762/bjoc.17.187

• -substituted-3,7-dihydro-4H-pyrazolo[3,4-d][1,2,3]triazin-4-ones 3 are reported in several references dealing with their synthesis, modification, and application [36], their non-oxidized derivatives 5 and 6 are yet, to the best of our knowledge, unknown in the literature. In the past, it was shown that ortho

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

• sulfur atom at the 3’-position, these compounds have proved to be structurally potent nucleoside analogues, and the best example is BCH-189. The majority of methods traditionally involves the chemical modification of nucleoside structures. It requires the creation of artificial sugars, which is

• modification. This review aims to provide a comprehensive overview on the reported methods in the literature to access 1,3-oxathiolane nucleosides. The first focus of this review is the construction of the 1,3-oxathiolane ring from different starting materials. The second focus involves the coupling of the 1,3

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• established, commercial polymers in solution [17]. We recently reported the self-assembly of polyethylene oxide (PEO) polymers into cylindrical nanostructures, also called supramolecular polymer bottlebrushes (SPBs), based on the end group modification with hydrogen bond forming benzenetrisurea (BTU) and

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

• applications [4][5]. As the production is easier, it also results in lower cost. According to Zhang et al., the challenge has been to obtain satisfactory properties without any chemical modification, while retaining the biocompatibility, biodegradability, and bioactivity [4]. However, Bagri et al. confirm that

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• by ligand modification. Although remarkable efforts have been made to elucidate and modify Cu complexes as photoredox catalysts for organic synthesis, the design of these complexes has not received much attention. If new complexes with improved redox and photophysical performances are designed, then

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• polymer modification by adding spatial and temporal control [12][13]. In recent years, heterogeneous photocatalysts have been performed in many photosynthetic reactions since they provide a more reasonable and easy way to synthesize the targeted products compared to the classical homogenous photocatalysts

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• this compounds are required. In this regard we suggested the modification of the alcohol tail of metronidazole by incorporating an N-heterocyclic moiety. Nitrogen-containing heterocycles play a vital role in agrochemicals and pharmaceuticals [3]. Among these heterocyclic systems, the 1H-1,2,3-triazoles

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• strategy, drug conjugated monomers can be directly used in the polymerization, eliminating the post-modification step [28][37][38][39]. In order to use micelles, prepared by PISA or traditional techniques, for targeting specific receptors, it is necessary that these materials are low-fouling, thus repel

• content (DLC, Table 1). These nanoparticles were already described in [42], but they are included in this publication for convenience of the reader. Modification with TPP The PISA particles with excess hydroxy groups on the surface were subsequently modified with the water-soluble TPP derivate, TPP-COOH

• the RAFT agent although there is no direct overlap. Full TPP endchain modification therefor equates to an intensity ratio of 43 (δ = 7.5–8.2 ppm) to 189 (δ = 3.4 ppm), which is equivalent to the signal intensity of 2.91 (δ = 3.4 ppm) to 0.68 (δ = 7.5–8.2 ppm) shown in Figure 2, suggesting complete

Base-free enantioselective S_N2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis

• Mili Litvajova,
• Emiliano Sorrentino,
• Brendan Twamley and
• Stephen J. Connon

Beilstein J. Org. Chem. 2021, 17, 2287–2294, doi:10.3762/bjoc.17.146

• selectivity. Attention first turned to the catalyst’s N-substituent. Catalyst 7a, bearing a benzyl group, was able to promote the transformation of 5a in moderate enantioselectivity (Table 1, entry 1). Modification of the N-benzyl unit to incorporate either electron-withdrawing or bulky substituents did not

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

• enantioselective polycylization reaction of 51 (Scheme 11) [69]. Modification of the aromatic ring system on the chiral side of the thiourea catalyst proved to be crucial, as both the reactivity and the enantioselectivity were significantly influenced by the stabilization of the cationic substrate and not by

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• azulene density (75 mol % azulene) was found to be an effective cathode modification layer in a bulk-heterojunction solar cell with a power conversion efficiency of 7.9%. Conclusion This review has described the chemical syntheses and key features of azulene-containing polymers reported in the last three

An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone)

• Jochen Löblein,
• Thomas Lorson,
• Miriam Komma,
• Tobias Kielholz,
• Maike Windbergs,
• Paul D. Dalton and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2021, 17, 2095–2101, doi:10.3762/bjoc.17.136

• photopolymerization for the hydrophilic modification of microfiber scaffolds obtained from hydrophobic medical-grade poly(ε-caprolactone) via melt-electrowriting. Contact angle measurements and Raman spectroscopy confirms the formation of a more hydrophilic coating of poly(2-hydroxyethyl methacrylate). Apart from

• surface modification, we also observe bulk polymerization, which is expected for this method, and currently limits the controllability of this procedure. Keywords: additive manufacturing; light-induced polymerization; self-initiated photografting and photopolymerization; surface-initiated polymerization

• ; surface modification; Introduction Additive manufacturing, commonly referred to as three-dimensional (3D) printing, is an approach to create physical objects using layer-by-layer [1] or voxel-by-voxel fabrication [2]. 3D printed materials can be used for a broad spectrum of applications, including

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• synthetic routes. Results and Discussion Substituent modification – alkylation/saponification route Based on the literature precedents, it appeared logical to start the preparation of SMAHOs by the alkylation of a malonate derivative followed by a monosaponification of the resulting diester. This strategy

• could be isolated in 70% and 47% yield, respectively (Scheme 2). Ester modification Meldrum's acid route We next turned our attention to the diversification of the ester group of SMAHOs. Our first approach was the use of substituted malonates, protected as Meldrum's acid derivatives, as the parent

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

• modification can be prepared. Strategically introduced PGs can be selectively removed to insert a branch or a chemical modification. However, to date, this approach has suffered dramatically from the severe aggregation and insolubility of cellooligosaccharides, permitting to obtain only relatively short

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

• , operating under mild conditions without the need of directing groups, using traceless electrons as sole redox reagents, presenting high scope and chemoselectivity. The robustness of the reaction was proved by the late-stage modification of pharmaceutically relevant compounds by promoting the azidation of a

• the need for directing groups, presenting a broad scope and satisfactory yields. The late-stage modification of complex molecules like (+)-artemisinin (69) and a (+)-tetrahydrogibberellic acid analogue 70 could be rapidly achieved in moderate yields (Scheme 25C). In 2014, Brown and Rasik employed

• the late-stage modification of amino acids and peptides in 2016 (Scheme 27A and B) [159]. The methodology facilitated the targeted C–H oxidative modifications in amino acids and peptides concomitant with the preservation of the α-center chirality in good yields and broad scope regarding the number of

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• table design showing which modification has duplex stabilizing properties, as well as improved nuclease resistance and cell activity, has been chosen for optimal visual presentation. This approach has spurred considerable interest since the introduction of positively charged groups results in ASOs with

• the center. The modifications chosen for inclusion into this review involve some of the more commonly used amine groups that have been attached as a single modification either on the nucleobase, sugar, or internucleotide linkage. When structurally depicted in this paper, modifications are shown with

• (poly)amine groups via the nucleobase on ASOs, thereby improving the RNA-binding affinity [26]. This strategy can be employed either on the nucleoside level, which requires many different nucleotide building blocks to be synthesized or via the so-called post-synthetic modification strategy of ONs. The

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• hydroxylated and methylated to tryprostatin A. Oxidative closure of the ringstructure then results in fumitremorgin C. Further modification of the structure leads to fumitremorgin B and verruculogen, which shares the same pathway [97][160][161][162]. Which enzyme is responsible for the conversion of

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• ruled out. Manganese-catalyzed late-stage C–H allylation The late-stage modification of peptides has received increasing attention due to the convenient and efficient modality. However, such protocols generally require substrate prefunctionalization and expensive metal catalysts, such as Pd [66][67][68

A systems-based framework to computationally describe putative transcription factors and signaling pathways regulating glycan biosynthesis

• Theodore Groth,
• Rudiyanto Gunawan and
• Sriram Neelamegham

Beilstein J. Org. Chem. 2021, 17, 1712–1724, doi:10.3762/bjoc.17.119

• , State University of New York, Buffalo, NY 14260, USA 10.3762/bjoc.17.119 Abstract Glycosylation is a common posttranslational modification, and glycan biosynthesis is regulated by a set of glycogenes. The role of transcription factors (TFs) in regulating the glycogenes and related glycosylation

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• linkages having the same number of atoms and linking bonds [2]. Not surprisingly, backbone modification has been a major focus of follow up attempts to improve the original PNA design. Early studies showed that maintaining proper distances (number of bonds) along the backbone and between the backbone and

• . Recently, more detailed biophysical and structural studies on S,S-cpPNA by Appella and co-workers [59][60] show that the S,S-configuration of cyclopentane modification enforces dihedral angles of PNA backbone favorable for binding to complementary DNA. PNA binding affinity and sequence selectivity increase

• ]. This property makes pyrrolidinyl α/β-dipeptide PNA especially suitable for double duplex invasion of dsDNA [66]. In general, pyrrolidinyl α/β-dipeptide PNA is another promising modification along with cyclopentane constrained PNAs studied by Kumar, Ganesh, and Appella. PNA modified at alpha and gamma

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• more attention of many research groups. In addition, the ease of modification, such as at the endocyclic nitrogen atom as aromatic fragment of isoindigo, makes it possible to fine-tune the electronic properties. These factors led to the beginning of many studies on isoindigo as a platform for the

• researchers in semiconductor materials has covered the field of organic electronics. The advantages of organic oligomeric and polymeric materials for applications in OFET and thin-film transistor (TFT) technologies are due to the ease of their directed chemical modification, mechanical flexibility, the

• a promising platform for creating materials for various purposes – from organic solar cells and transistors to materials for biomedical applications. The possibility of easy modification and easy accessibility of the starting reagents for the synthesis of polysubstituted isoindigo derivatives

Iodine-catalyzed electrophilic substitution of indoles: Synthesis of (un)symmetrical diindolylmethanes with a quaternary carbon center

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati,
• Andhika B. Mahardhika,
• Lukas L. Wendt and
• Christa E. Müller

Beilstein J. Org. Chem. 2021, 17, 1464–1475, doi:10.3762/bjoc.17.102

• reaction with differently substitute indole derivatives 2. Substrate scope of the reaction of 1f–i with trifluoromethyl(indolyl)phenylmethanols 1: modification of the aryl group. Substrate scope of the reaction of 1j–l with trifluoromethyl(indolyl)phenylmethanols 1: modification of the trifluoromethyl

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• developing a route for the synthesis of enantiomer 2 by modification of the established protocol used for the synthesis of 1. The plan was that the alternative strategy would lead to an improvement in the overall yield whilst eliminating some of the troublesome steps. Results and Discussion The synthetic

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• homologation [3]. Much effort has been devoted to developing a procedure for the synthesis of alkynes from carbonyl compounds, and the Corey–Fuchs method, the Seyferth–Gilbert method, and the Ohira–Bestmann modification have been developed (Scheme 1) [4][5][6][7]. These methods consist of the Wittig or Horner