One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

• 10.3762/bjoc.16.143 Abstract The catalytic conversion of (ligno)cellulose is currently subject of intense research. Isosorbide is one of the interesting products that can be produced from (ligno)cellulose as it can be used for the synthesis of a wide range of pharmaceuticals, chemicals, and polymers

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

• crosslinked polymers made up of cyclodextrins. The reactive hydroxy groups of CDs allow them to act as multifunctional monomers capable of crosslinking to bi- or multifunctional chemicals. The most common NS synthetic pathway consists in dissolving the chosen CD and an appropriate crosslinker in organic polar

• . 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

• , applied to organic syntheses and polymers has gained growing interest in recent years [14][15][16][17][18]. Mechanochemical syntheses are safe and represent efficient activation methods for greener processes, avoiding the use of solvents and reducing energy consumption. Recently, many examples for

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• Shirakawa, leading to their shared award of the 2000 Chemistry Nobel Prize for “the discovery and development of conductive polymers” [101]. For the following 60 years, and still to this day, organic electronics is a vibrant field of research within materials chemistry and physics as a potential source of

• conjugation and polarisation of the surrounding medium, which is enhanced by low εr(ω) values [115][116][117][118]. The charge is transported in organic materials by “hopping” between the quantum states. The amorphous nature of most polymers produces a low symmetry and anisotropy for the charge transport

• . Hence, the charge mobility in organic semiconductors is typically much lower than in crystalline inorganic materials [115]. Conjugated polymers that are rigid will generally have faster intrachain charge transport rather than interlayer hopping transport (Figure 8) [107][115]. The process is highly

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

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

• ; photocatalysis; thiyl radical; Introduction Organic disulfides are often used as the skeleton for drugs, pesticides, rubber auxiliaries, polymers, and electronic materials [1]. Over the past decade, organic disulfide-involving photoreactions have attracted increasing attention. Disulfides have versatile

• . In 1996, Burton and co-workers reported the stereoselective synthesis of cis-1,2-difluorotriethylsilyethylene and its conversion to a variety of cis-1,2-difluoroethylene synthons, which are important building blocks in the preparation of fluorine-containing pharmaceuticals, polymers, and bioactive

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• of the richest families of stable and persistent organic radicals with applications ranging from catalysis of selective oxidation processes and mechanistic studies to production of polymers, energy storage, magnetic materials design and spectroscopic studies of biological objects. Compared to other N

• used in the development of organic magnetic materials [1], organic batteries [2][3][4], in the preparation of polymers by living polymerization [5][6], in the studies of biomolecules and living systems by EPR [7] and NMR [8] techniques. Stable N-oxyl radicals occupy a central place in organic chemistry

Synthesis and properties of tetrathiafulvalenes bearing 6-aryl-1,4-dithiafulvenes

• Aya Yoshimura,
• Hitoshi Kimura,
• Kohei Kagawa,
• Mayuka Yoshioka,
• Toshiki Itou,
• Dhananjayan Vasu,
• Takashi Shirahata,
• Hideki Yorimitsu and
• Yohji Misaki

Beilstein J. Org. Chem. 2020, 16, 974–981, doi:10.3762/bjoc.16.86

• ion complexes with DDQ or iodine were reported [17][18][19][20][21][22][23][24]. Peripherally thiophene-functionalized TTFs, as potential precursors to conducting polymers, and organic metals were also prepared and characterized [25][26][27][28][29]. To design more tempting molecules, the attachment

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• recovery and reuse. The authors did not observe any decrease in the photocatalytic activity of the material even after four reuses. Another very promising catalytic platform for this transformation is the covalent organic framework (COF), a class of porous crystalline polymers built from molecular building

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• alternatives such as rylenes [56] or conjugated polymers [57] with the focus to receive materials covering a broad absorption range up to the near infrared (NIR) part. Nevertheless, they have not reached the necessary practical use as cyanines explainable by the modest solubility in many industrial matrix

• review provides available references disclosing controlled polymer synthesis via photoinduced electron transfer reactions [129]. In addition to those approaches, photo-induced ATRP has been widely used to synthesize well-defined polymers by controlled radical polymerization either with or without heavy

• , zwitterionic and anionic patterns shown in Scheme 10. The polymers obtained exhibited quite high molecular weights (more than 2 × 105 g·mol−1) and failed to exhibit living character [81]. However, this system exhibited a successful route with Cu(II) catalysts at the ppm scale [81]. Quite recently, NIR light

Room-temperature Pd/Ag direct arylation enabled by a radical pathway

• Amy L. Mayhugh and
• Christine K. Luscombe

Beilstein J. Org. Chem. 2020, 16, 384–390, doi:10.3762/bjoc.16.36

• radical; visible light; Introduction π-Conjugated polymers are of significant interest as they have the potential to combine the mechanical flexibility and affordability of synthetic polymers with the optical and electronic properties of semiconductors. One of the limitations to this field’s continued

• reduce waste and toxicity by removing the need for stoichiometric amounts of toxic organometallics [2]. While significant progress has been made in DArP, C–H bonds are more challenging to functionalize than their C–M counterparts. Known DArP conditions have limited monomers that can produce polymers with

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• block for the assembly of homo and hetero-organometallic complexes. The 3- and 4-pyridylphosphine derivatives 5 have also been successfully used as templates for assembling supramolecular structures and coordination polymers [54][59]. Halogenated ring-fused pyridine reagents can also be used to generate

Formal preparation of regioregular and alternating thiophene–thiophene copolymers bearing different substituents

• Atsunori Mori,
• Keisuke Fujita,
• Chihiro Kubota,
• Toyoko Suzuki,
• Kentaro Okano,
• Takuya Matsumoto,
• Takashi Nishino and
• Masaki Horie

Beilstein J. Org. Chem. 2020, 16, 317–324, doi:10.3762/bjoc.16.31

• copolymer; nickel(II) catalyst; oligosiloxane; regioregular polythiophene; solubility; Introduction Polythiophenes attract much attention in materials science because of their extended π-conjugation, which is applied for a wide range of electronic materials. In particular, the regioregular polymers with a

• of monomer/catalyst feed, and the molecular weight distributions were relatively narrow. Solubility tests of the obtained polymers were performed as summarized in Figure 1. Although the alternating copolymer 6b, substituted with methyl and C-4 alkyl groups as well as terminal pentamethyldisiloxane

• (ATR): 2956, 2925, 2855, 1728, 1445, 1252, 1057, 841, 806, 782, 753 cm−1. The other polymers 6c–e were synthesized similarly. The polymerization was continued for 18–24 h or terminated after 1 h when 4 bearing a fluoroalkyl substituent was employed, due to faster polymerization, which brought about an

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• a scan rate of more than 10 °C, it was not possible to reproduce the peaks reported during the first scan. The thermal behavior of the thioureas in this study is similar to that of polymers becoming semicrystalline or an amorphous solid after subjecting them to repeated heating and cooling cycles

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• polymers (HCPs), a series of 9-phenylcarbazole (9-PCz) HCPs (P1–P11) has been made by changing the molar ratio of cross-linker to monomer, the reaction temperature T1, the used amount of catalyst and the concentration of reactants. Fourier transform infrared spectroscopy was utilized to characterize the

• structure of the obtained polymers. The TG analysis of the HCPs showed good thermal stability. More importantly, a comparative study on the porosity revealed that: the molar ratio of cross-linker to monomer was the main influence factor of the BET specific surface area. Increasing the reaction temperature

• ; hyper-cross-linked polymers; microporous; Introduction HCPs get more attention in recent years due to their high BET specific surface area [1], made under mild reaction conditions [2], used nonprecious materials as catalyst [3] and wide applications [4][5][6][7][8][9], etc. The synthesis methods of

Progress in metathesis chemistry

• Karol Grela and
• Anna Kajetanowicz

Beilstein J. Org. Chem. 2019, 15, 2765–2766, doi:10.3762/bjoc.15.267

• by Kotha et al. [4], on artificial metalloproteins by Okuda et al. [5], on stereoretentive ruthenium dithiolate catalysts by Mauduit et al. [6], on unsymmetrical NHC ligands by Grisi et al. [7], on polymers by Kudryavtsev [8] and on polyhedral oligomeric silsesquioxanes by Pietraszuk et al. [9

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• ]thiophene; thieno[2',3':4,5]thieno[3,2-b]indole; Introduction The thieno[3,2-b]thiophene (TT) unit is highly demanded in modern organic synthesis since TT-based compounds have a variety of applications, e.g., in the field of organic electronics. Indeed, TT-based polymers and small molecules are used as

Synthetic terpenoids in the world of fragrances: Iso E Super^® is the showcase

• Alexey Stepanyuk and
• Andreas Kirschning

Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252

• versatile monoterpenes to be used as starting material for generating products in various industries. These include polymers, insect repellents, vitamins, flavours and fragrances [16]. Commercially, it is obtained from turpentine, a side product in paper manufacturing. Its main constituents are α-pinene (3

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

• Aydan Yadigarli,
• Qimeng Song,
• Sergey I. Druzhinin and
• Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

• permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin

• polymers possess an enormous impact on the properties of polymers and polymer thin films. For ultrathin films, in which the film thickness is in the order of the radius of gyration, special effects of confinement have been observed. Prominent examples are the properties of substrate-supported ultrathin

• -controlled drug delivery systems [4][6][7][8][9][10], as well as dynamics of polymers at interfaces [11]. To be able to understand local properties of polymers, in particular in nanoenvironments of polymeric vesicles (polymersomes), comprising a hydrophilic corona and a hydrophobic wall [1][12], or in

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• conversions the Mortreux catalyst system Mo(CO)6/ArOH was used at elevated temperatures. Because of the electronic properties of the ferrocene unit, polymers of acetylenic ferrocenes can be used for example as molecular wires [75]. Coming to ferrocenophanes, mainly carbon-bridged compounds are known [76][77

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• (I) complexes can be discrete species [35][36][37][38], coordination driven supramolecules [35][42] or coordination polymers [39][40][42]. To the best of our knowledge, silver crown thioether complexes were never reported as catalysts. Recently, we described a flexible bis-dialkyl thioether ligand

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• have led to applications in molecular recognition, sensing, molecular machines and devices, supramolecular polymers, stimuli-responsive materials, supramolecular catalysis and drug-delivery systems [4][5][6][7]. Inspired by the attractive role of various N-heterocyclic building blocks such as

• polymers etc. [14][15]. Noncovalent interactions play a dynamic role in the binding mechanism of triazoles as macrocyclic receptors. It has been reported that the combined effects of both an electron lone pair on the nitrogen of the heterocycle and the acidic C5–H proton make 1,2,3-triazoles interesting

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• the formation of several materials, including dynamic polymers (dynamers) [190], hydrogels [191], and precursors to charge-transfer complexes [181][234][235]. Dynamers, referred to as dynamers, are a class of adaptive polymers formed through reversible covalent bonds or noncovalent interactions

• room temperature and the resulting polymers were processed as thin films. As a result of the dynamic nature of the Diels–Alder adducts, the films were shown to possess self-healing capabilities [190]. Similarly, Wei et al. employed DAC to create a self-healing hydrogel using a polysaccharide

• metathesis polymerisation (ROMP) to generate facially amphiphilic polymers [182][235][237][238]. Ilker et al. employed the DAC between alkyl pentafulvenes and maleic anhydride to initially prepare norbornene anhydride monomers that could be further functionalised to afford norbornene imide monomers (Scheme

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

• HGCMs containing one host and other guest moieties have been used to construct intramolecular complexes [36], cyclic oligomers [37], supramolecular polymers [23][38][39][40], gels [41][42], etc. However, AB-type HGCMs were still limited to obtain non-spherical stimuli-responsive supramolecular self

Installation of -SO₂F groups onto primary amides

• Jing Liu,
• Shi-Meng Wang,
• Njud S. Alharbi and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 1907–1912, doi:10.3762/bjoc.15.186

• , and a vast number of synthetic structures, such as polymers, biologically active compounds and pharmaceutical products [32][33][34][35]. However, the installation of sulfonyl fluoride (SO2F) onto nitrogen atoms of amides has not been achieved, which, if accomplished, would provide a very important

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• chemistry. The occurrence of an amide and/or ester bond is widely realized in organic molecules, proteins, natural products, pharmaceuticals, polymers and agrochemicals [1][2][3][4][5]. The conventional synthesis of amides involves the reaction of carboxylic acids or their derivatives such as acyl halides

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

• -conjugated polymers [29][30][31]. On the other hand, γ-CD is relatively less employed in the synthesis of mechanically interlocked molecules despite of its ability to form interesting 1:2 inclusion complexes, and there are only few examples of rotaxane and catenane featuring γ-CD as an interlocked macrocycle

• , suggesting intercomponent stabilization could play an important role in directing higher level structures in mechanically interlocked molecules, reminiscent to the intra-strands interactions that stabilize high-order structures in (bio)polymers. Conclusion In summary, complex hetero[n]rotaxanes have been