Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• acid [13], polyvinylsulfonic acid (PVSA) [14], kaolin-supported H2SO4 [15], polyvinylpolypyrrolidone-supported triflic acid (PVPP.OTf) [16], ascorbic acid [17], phosphoric acid [18], benzenesulfonic acid [19], chitosan–SO3H (CTSA) [20], phthalimide-N-sulfonic acid (PISA) [21] and SiO2-KHSO4 [22] as

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• , PR China 10.3762/bjoc.19.45 Abstract We synthesized a new tetraphenylethylene-modified chitosan bioconjugate, CS-TPE, that shows the aggregation-induced emission effect. It can self-assemble into fluorescent polymeric nanoparticles in an aqueous solution at pH 5.3 either alone or with the water

• fluorescence emission based on CS-TPE or TBTQ-C6/CS-TPE may find applications in various fields, including the development of visual oral drug delivery systems. Keywords: chitosan; nanoparticle; tetraphenylethylene; tribenzotriquinacene; Introduction Stimuli-responsive assemblies in aqueous media have drawn

• -induced emission (AIE) character [20][21]. Chitosan (CS) is a natural cationic polysaccharide, which is considered an ideal material for the construction of drug delivery systems due to its nontoxic, biocompatible, biodegradable, and easily functionalized properties [22]. Herein, we designed and

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• through either (i) the cationic nature of the CD such as poly-β-CD-C6 or (ii) coating of non-ionic 6-O-capro-β-CD with the cationic polymer chitosan (CS). Uncoated 6-O-capro-β-CD negatively charged NPs were used as control formulation. Results and Discussion Fabrication and in vitro characterization of

• CPT-loaded amphiphilic CD NPs CPT-loaded amphiphilic CD nanoparticles have been previously optimized in our laboratories [9], as reported, NPs using two different amphiphilic CDs were prepared and 6-O-capro-β-CD nanoparticles coated with chitosan (CS) to obtain a positively charged surface. In vitro

• surface with chitosan, a cationic coating material. The theoretical interpretations so far have been that the drug can be adsorbed in the coating material or weakly bound to the coating polymer structure, and it will be released first. The data obtained from the kinetic modeling provided results that

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

• polysaccharides. Xanthan gum, locust bean gum or chitosan can be crosslinked using citric acid in the presence of β-cyclodextrin to produce insoluble matrices. In this work, polymeric foams based on those polysaccharides and saponin have been prepared using a green synthesis method to increase the porosity of the

• matrices. The saponin of soapbark (Quillaja saponaria) has been used to obtain foams using different procedures. The influence of the synthesis path on the porosity of the materials and their corresponding sorption capacities in the aqueous phase were evaluated. Keywords: chitosan; cyclodextrin polymers

• technologies [23] or phytoremediation [24]. When chitosan and saponins are mixed, their foamability properties change, leading to a longer foam stability due to the higher viscosity achieved [25]. The use of chitosan to absorb saponins have been studied for different purposes. A high specific area activated

Synthesis of protected precursors of chitin oligosaccharides by electrochemical polyglycosylation of thioglycosides

• Md Azadur Rahman,
• Kana Kuroda,
• Hirofumi Endo,
• Norihiko Sasaki,
• Tomoaki Hamada,
• Hiraku Sakai and
• Toshiki Nokami

Beilstein J. Org. Chem. 2022, 18, 1133–1139, doi:10.3762/bjoc.18.117

• from natural sources or by synthesis via chemical glycosylation [2]. Total syntheses of chitin and chitosan oligosaccharides based on conventional chemical glycosylation of protected monosaccharides as building blocks have already been reported. Convergent synthesis using oligosaccharide building

• solvent was removed under reduced pressure. The thus-obtained crude product (110 mg) was purified by preparative GPC using CHCl3 as eluent. Structures of chitin and chitosan oligosaccharides. Effect of the anomeric leaving group on the yield of oligosaccharides. Influence of the glycosylation temperature

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

• without any remarkable decrease in its catalytic activity. A novel cobalt catalyst with cobalt immobilized on nanochitosan fibers (Co-DMM@MNPs/chitosan) was fabricated using dimethyl malonate [36] and its applicability tested in a Sonogashira coupling reaction. The catalyst was found to be highly active

• 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

• reaction (Scheme 31). Non-nanoparticle-based protocols Nanoparticles are materials with sizes around nanometer scales. The used nanoparticles are environmentally friendly magnetic cross-linked chitosan fibers which is a natural polysaccharide polymer. In this regard the use of such polymers is promising

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• , India Department of Chemistry, Presidency University, Kolkata-700073, India Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata-700103, India 10.3762/bjoc.18.14 Abstract A heterogeneous and magnetically recyclable Ni–chitosan nanocatalyst was synthesized and thoroughly

• yield, the use of an eco-friendly solvent and a recyclable nanocatalyst, as well as reaction at room temperature. Keywords: 1,4-DHPs; green synthesis; magnetically recyclable catalyst; Ni–chitosan nanoparticles; ultrasonication; Introduction Homogeneous catalysts, despite having an outstanding

• . Chitosan is one of the most abundant bio-based polymers in nature [9]. It is the N-deacetylated form of chitin found in industrial waste [10]. Chitosan is a broadly used natural polymer because of properties such as biocompatibility, low cost, and nontoxicity. It has diverse applications, such as drug

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

• . Common cryogel compositions include natural polymers such as gelatin and chitosan, and synthetic acrylamide-based polymers and poly(vinyl alcohol) (PVA) [12][13][14]. The reader is directed to a recent review by Thakor and co-workers which discusses cryogel synthesis in greater depth [15]. 2. Cryogel

• hydrolysis [8]. It has also been found that degradation of chitosan/dextran cryogels resulted in an average increase in pore size, possibly due to thinning of the pore walls and reduction in crosslinks [32]. In general, mechanical property analysis of degraded cryogels is a topic largely overlooked by

• [11][33][39]. Thermoresponsive cryogels comprising oligoethylene glycol have also been reported with dual shape memory behaviour [40]. Natural polymers such as cellulose derivatives, chitosan, gelatin, and dextran exhibit temperature-responsive properties and have been used in cryogels. 3.2. pH

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

• chitosan Chitin is a linear polysaccharide composed of β(1–4)-linked 2-acetamido-2-deoxy-ᴅ-glucopyranose (GlcNAc) repeating units, which mainly exists in the exoskeleton of crustaceans and insects, as well as in the cell-wall of fungi [209][210]. Chitosan, its partially N-deacetylated analogue, has vast

• industrial applications in coating materials, cosmetics and pharmaceuticals [211]. Owing to their superior biological and mechanical properties, chitin and chitosan are used in fibers, gels, sponges, films, beads, and nanoparticles [212]. Tunable stiffness, solubility, and transparency can be obtained by

• activity, as demonstrated using partially acetylated COS obtained by enzymatic degradation of chitosan promoted by hydrolases [221]. Chemical degradation of chitin promoted by acid treatment [222][223][224][225][226][227][228] or using chitinases and chitosanases [229][230][231] generates mixtures of short

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• , damaging the VLPs. Therefore, further studies should be on how this can be administered in the pellets at industrial levels. Other studies by IM injection of chemically modified chitosan nanoparticles loaded with anti-VP28 RNA [20] and antisense plasmid constructs for VP28 [24] have shown protection of 95

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada 10.3762/bjoc.16.201 Abstract In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a

• benign conditions, outcompeting the use of other catalysts supported on biomass-based nanomaterials, including cellulose nanocrystals. These initial results show the potential for using chitinous nanomaterials as effective catalyst supports in cross-coupling reactions. Keywords: chitin; chitosan; Heck

• the use of ammonium persulfate as a mild oxidizing agent to liberate the nanocrystallites existing within bulk chitin to yield ChNC with carboxylate functionalities [16]. Moreover, deacetylation of ChNCs in alkaline conditions, in the presence of NaBH4, led to chitosan nanocrystals (ChsNCs) with

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• combination of chitosan (137) and laponite® RD (132) [99]. The synthetic strategy to this catalyst is shown in Scheme 29. At first, Fe(II)/Fe(III)-loaded laponite RD, 133, was prepared by adding a solution of Fe(II)/Fe(III) ions to a dispersed solution of 132. In the next step, a solution of 137 was added to

• another study, Shaabani reported crosslinked chitosan nanoparticles-anchored magnetic multiwalled carbon nanotubes Cu–CS NPs/MWCNT@Fe3O4 (141) as a bionanoreactor catalyst, and the catalytic activity of 141 in 1,2,3-triazole syntheses was explored [100]. A schematic pathway for the creation of 141 is

• presented in Scheme 31. In the first step, chitosan nanoparticles/multiwalled carbon nanotubes (CS NPs/MWCNT, 139) were prepared by the addition of MWCNT–COOH to an acetic acid solution of chitosan (CS, 137). Subsequently, a solution of sodium tripolyphosphate (138) was added to the previous solution. After

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• exhibited enhanced membrane permeability compared with the pure API [85]. The preparation of co-crystals of 5FU with other API’s (imatinib [86] and piperazine [87]) using LAG has also been reported. Solid dispersions of acyclovir (20%) in neutral carriers (chitosan, hydroxypropylmethyl cellulose K100M® or

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• . Simultaneously, Shen, Zhang and co-workers reported a milder regioselective trifluoromethylation of 8-aminoquinolines using the supported catalyst CS@Cu(OAc)2 (CS = chitosan), potassium persulfate as the oxidant and CF3SO2Na as the CF3• source (Scheme 45) [68]. After optimisation of the reaction conditions, the

• authors studied the effect of structural variations in the substrate (R1 = aryl, heteroaryl, alkyl; R2 = H, 6-OMe, 2-Me). Aniline amides gave no conversion nor did quinoline having an ester group at the 8 position instead of the 8-amino group. The chitosan-based copper catalyst was efficiently reused in

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• 114 [224] or chitosan 115 [225]. The functionalization of polyacrylamide obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization was also recently reported to produce 116 (Figure 31). However, the conditions of the Moedritzer–Irani reaction induced the hydrolysis of the

Solid-state mechanochemical ω-functionalization of poly(ethylene glycol)

• Michael Y. Malca,
• Pierre-Olivier Ferko,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2017, 13, 1963–1968, doi:10.3762/bjoc.13.191

• the functionalization of premade polymers. Recently, Yan and co-workers used ball milling to deacetylate chitin to afford chitosan [30]. We now provide a proof-of-principle demonstration of mechanochemical ω-functionalization of α-protected methoxy-PEG (mPEG) with –COOH, –OTs, –NH2, –Br, and –SH

β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules

• Liang Yan,
• Duc-Truc Pham,
• Philip Clements,
• Stephen F. Lincoln,
• Jie Wang,
• Xuhong Guo and
• Christopher J. Easton

Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183

• and the PAAADen, PAAADhn or PAAADddn strands. The adamantyl group is selected as the guest substituent as it is strongly complexed by β-CD [48], β-CD oligomers [3][4] and β-CD-substituted polymers [10][14][16], and drives the self-assembly of aqueous chitosan [1][5][9], hyaluronic acid [8][9] and poly

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• -assisted method to prepare Pd catalysts immobilized on modified chitosan (Scheme 1). Although these catalysts were found to be effective in the Suzuki reaction after three cycles, the modification conditions of chitosan were rigorous. As catalyst-supported material, layered double hydroxides (LDHs) have

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• or embed the AgNPs into a supporting matrix. The loading of AgNPs on different substrates has been reported, for instance, SiO2 [23], TiO2 [24], Al2O3 [25], porous carbon [26], carbonaceous matrix [27], carboxymethyl chitosan [28], zeolite [29], cellulose [30], ZnO paper [31] and polymers such as PVP

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• glucose and galactose moieties multi-displayed on gold surface acted as target for asialoglycoprotein receptors, over-expressed on liver cancer cells, delivering selectively the anticancer drug Au(I). In search of novel antimicrobial antigens, chitosan-streptomycin GAuNPs (CA NPs), i.e., carbohydrate

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• [13][24]. Similarly, important carbohydrate-based biopolymers such as cellulose, chitin, chitosan, dextran, cyclodextrin, and hyaluronic acid, which differ not only in elemental composition, but also in chemo-physical properties, have also been successfully utilised in the preparation of CDs, where

• , readily available neutral carbohydrate such as glucose as the carbon source in combination with a nitrogen-containing molecule. Glucosamine hydrochloride, which is a byproduct from the hydrolysis of chitosan and chitin polysaccharides found on crustacean shells, bears an amine functionality at C-2 and

• -derived CDs, the different features and functional groups present in those distinct carbohydrate chains, will have an effect in the final properties of the CDs synthesised from them. Pramanik et al. exploited this hypothesis in the synthesis of CDs from three different polysaccharides: chitosan (Chi-CDs

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• negative controls. As positive control, we used chitosan (β-1,4 linked glucosamine) with average molecular weight, a fungal elicitor with known effect as NO and ROS inductor on A. thaliana [61]. Intracellular ROS was visualized using 2’,7’-dichlorodihydrofluorescein diacetate (H2DCF DA) as fluorescence

Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

• Barbara Dmochowska,
• Karol Sikora,
• Anna Woziwodzka,
• Jacek Piosik and
• Beata Podgórska

Beilstein J. Org. Chem. 2016, 12, 1434–1439, doi:10.3762/bjoc.12.138

• and sugar moieties were described before [22][25][26]. It was shown that quaternization of chitosan increases its antimicrobial activity; such polymer is proposed to be used as a wound dressing after surgeries to eliminate infections and to improve the healing process [27][28][29]. Moreover, the

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• interaction and may promote the formation of metal nanoparticle clustering. Cu(I)-based system have been used in alkyne/azide [3 + 2] cycloadditions, while Pd(II)-based catalysts have been used in C–C couplings reactions (Scheme 7) [34]. An example of water-soluble β- and γ-CD/chitosan derivatives have been

• studied for binding Gd(III) chelates that bear hydrophobic substituents and negative charges [35]. These bio-polymers were easily prepared in two reaction steps by reacting CDs with maleic anhydride followed by activation with carbodiimide to form amide linkages with amino groups of chitosan. The

• esterification of CD was promoted by MW irradiation, while the chitosan coupling used a water-soluble carbodiimide, N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, under US. A mild sonication at rt using HDI enabled efficient CDs reticulation in the presence of lipases (Scheme 7) whose biocatalytic