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

• hydroxide. In the second step, the formed zirconium hydroxide undergoes a sulfate impregnation, utilizing sulfuric acid in the presence of polyvinylpyrrolidone (PVP) as the surfactant, to prevent particle agglomeration, leading to the formation of the desired sulfated zirconia nanoparticles after a last

• the one suggested by Khalafi-Nezhad et al. for LPMNPs, where activation of the carbonyl compound by the nanocatalyst initiates the indole attack (Scheme 21) [117]. A year later, Chen and his research team created Lewis acid-surfactant-SiO2-combined (LASSC) nanocatalysts by combining Lewis acid

• surfactant and silica as the carrier providing the most promising results. Solid grinding was also employed, removing the need for a solvent and accelerating the reaction rate to 20 minutes and product yields to 99% without the need for conventional heating. Replacement of the Lewis acid or the silica

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• pyrrolidine at 0 °C, the pentafulvene derivative 36 was obtained with 63% yield via an additional ring-opening process. Similar skeletal transformation reactions were observed for azulene derivatives bearing similar substructures. The reaction of 1 with TCNE in an aqueous medium containing a surfactant

• results in the formation of a 6,6-dicyano-heteropentafulvene derivative 37 as an additional byproduct along with the typical TCBD adduct 4 (Scheme 14) [117]. The yields and formation ratios of 4 and 37 depend on the type and concentration of the surfactant employed. For instance, when the nonionic

• surfactant, Brij 30, was used as the reaction solvent at a concentration of 20 mM, exceeding the critical micelle concentration, 4 and 37 were obtained in a ratio of 53:47, with 64% yield. Notably, 37 exhibits instability in silica gel and polar solvents. In particular, when 37 is kept in ethyl acetate or

Preparing a liquid crystalline dispersion of carbon nanotubes with high aspect ratio

• Keiko Kojima,
• Nodoka Kosugi,
• Hirokuni Jintoku,
• Kazufumi Kobashi and
• Toshiya Okazaki

Beilstein J. Org. Chem. 2024, 20, 52–58, doi:10.3762/bjoc.20.7

• 305-8571, Japan 10.3762/bjoc.20.7 Abstract We successfully prepared a surfactant-assisted carbon nanotube (CNT) liquid crystal (LC) dispersion with double-walled CNTs (DWCNTs) having a high aspect ratio (≈1378). Compared to dispersions of single-walled CNTs (SWCNTs) with lower aspect ratio, the

• the dispersed rod-like CNTs, either isolated or bundled [5][7][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In previous studies, we prepared surfactant-stabilized aqueous dispersions of SWCNT LC and evaluated their dispersion states using the differential centrifugal sedimentation (DCS

• , Figure S1e) [26]. The DWCNT powder was dispersed with a surfactant of sodium cholate (SC) in water by a two-step process [22][23] (see the Experimental section). The size distribution of the DWCNTs in the dispersion was estimated by DCS method (Figure 1a). The observed intense peak at approximately 9 nm

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• a higher degree of polymerization. As the frequency of radical entry decreases with the particle number at a certain initiator concentration, the rate of polymerization and molecular weight can be boosted by raising the number of particles, e.g. by tuning the monomer to surfactant ratio. The final

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

• specific area of the matrix is intended to be increased, permitting a greater accessibility to β-cyclodextrin sites. Results and Discussion Production of saponin foams As a first step, the determination of the foamability of saponin aqueous solutions allows us to find the surfactant concentration for which

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

• -friendliness. Ren and colleagues [59] recently reported the preparation of an enantiopure 1,3-oxathiolane 65 utilizing a multienzymatic cascade protocol (Scheme 21). The combined use of surfactant-treated Subtilisin Carlsberg (STS) and Candida antarctica lipase B (CAL-B) resulted in the 1,3-oxathiolane ring in

• surfactant. Exceptionally, the end product was obtained in 99.9% ee by using whole-cell Klebsiella oxytoca catalysis and enantioselective resolution of the racemic mixture at 30 °C, pH 7.0, a substrate concentration of 1.5 g/L, and no additives. As compared to nearly all of the lipase-catalyzed methods to

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• OMe, NO2, or Cl groups, and epoxides (149 and 150), DBU as catalyst, CTAB as surfactant, and water as solvent. The use of cyclohexene oxide (149) provided oxa-aza-benzo[a]anthracene derivatives 151 in excellent yields (90–96%). On the other hand, the use of styrene oxide (150) provided oxa-aza

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

• stop after a certain chain length, as the active site becomes overcrowded. Thus, by modifying the reaction medium, a better control over the DP may be achieved. Longer cellulose chains (DP > 100) were obtained using DMAc/LiCl as reaction solvent and a cellulose surfactant complex, even though in low

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

• -melanin. Additionally, the surfactant protein D (SP-D), a soluble C-type lectin receptor (CLR), is also able to recognise DHN-melanin and opsonize it to increase the immune response. However, MelLec receptors are only present on some endothelial and myeloid cells [156][157]. Fumigaclavines Fumigaclavine C

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

Secondary metabolites of Bacillus subtilis impact the assembly of soil-derived semisynthetic bacterial communities

• Heiko T. Kiesewalter,
• Carlos N. Lozano-Andrade,
• Mikael L. Strube and
• Ákos T. Kovács

Beilstein J. Org. Chem. 2020, 16, 2983–2998, doi:10.3762/bjoc.16.248

• surfactin bioactivity is specifically evoked by the surfactant activity triggering cell lysis due to penetration of the bacterial lipid bilayer membranes and the formation of ion-conducting channels [40][41][42]. The bioactivity of surfactin was shown against Listeria spp. and Legionella monocytogenes [43

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• interaction of the alkyl chains. Keywords: dirhamnolipid ester; gemini surfactant; rheology; reverse wormlike micelle (RWLM); Introduction Surfactants have both hydrophilic and hydrophobic groups and are therefore amphiphilic molecules. Due to their unique molecular structure, surfactants are essential

• environmentally friendly biosurfactants because they are 100% biodegradable and are more compatible with water organisms than traditional surfactants. In solution, surfactants self-assemble into micelles with different shapes (spherical, cylindrical, double layer, etc.). In aqueous solution, the surfactant

• hydrophobic groups are oriented towards the solvent. One structure which can be formed by surfactants are so-called wormlike micelles, that are characterized by a high anisotropic structure. These micelles can, if the concentration and dynamics of the surfactant micelles is right, build viscosity since the

Easy access to a carbohydrate-based template for stimuli-responsive surfactants

• Thomas Holmstrøm,
• Daniel Raydan and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2020, 16, 2788–2794, doi:10.3762/bjoc.16.229

• surfactant with amphiphilic properties induced by the presence of Zn2+ ions (Figure 1b). In order to synthesize a glucopyranose-based molecular switch, a 2,4- or 3,6-functional group pattern is needed as these positions reside cis on the ring, making them pointing in the same direction of the 1C4

• order to afford an amino functionality on the 2,4-positions thereby giving diamines 9, 10, and 11 (Scheme 2). Having amino groups on these two positions fulfills the requirement of the compound to become a stimuli-responsive surfactant based on the earlier studies by Yuasa and co-workers [11][12

• synthesize a new surfactant from the anomeric mixture of compound 5. By functionalizing the 3-OH and 6-OH groups with picoloyl groups, using picolinic acid in the presence of N,N'-diisopropylcarbodiimide (DIC) and 4-dimethylaminopyridine (DMAP), an anomeric mixture of diazide 18 was obtained. The picoloyl

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• aerosol-assisted self-assembly using amphiphilic triblock copolymers as template and low-molecular weight soluble phenol resin as carbon source. The amphiphilic surfactant influences the pore size and mesostructure of the resulting spherical carbons. Finally, the template is removed by calcination [97

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

• 2 days at 100 °C, a solid was obtained, which was then filtered off, washed with distilled water, and dried. In the next step, the surfactant pluronic P123 was removed by the Soxhlet extraction method to produce a white solid. Then, 58 was synthesized using 57 and copper(II) acetate in methanol at

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• reaction of aza compounds [43][44]. Again, a Ru nanoparticle-catalysed C–H selenylation of indoles was reported by Lin et al. [45]. Herein, we report the Ru-catalysed regioselective synthesis of C3 alkenylindoles using a near-naked, surfactant-free, and recyclable Ru nanocatalyst in a heterogeneous manner

• . Results and Discussion Synthesis and characterisation of the Ru nanocatalyst The surfactant- and stabiliser-free RuNC was synthesised photochemically, based on a procedure that we have previously reported for the synthesis of Pd nanoparticles [46][47]. The synthesised RuNC, obtained directly after

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• in an aqueous medium (Scheme 9). In order to increase the solubility of reactants in aqueous medium cationic surfactant (cetyl trimethylammonium bromide: CTAB) has been used which has also increased the yield of the product. Aliphatic aldehydes resulted in lower yields (65 and 76%) whereas

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• [30] or the assembly of Au nanoparticles [31]. It is our hypothesis that CTAB, which serves as surfactant and is essential in the synthesis of AuNR in seed-mediated growth processes, acts as a competitive binder to the CD cavity and prevents the reversible self-assembly. In fact, CTAB has a more than

• = 690 nm for the LSPR band. After the ligand exchange the bands shift to λ = 528 nm TSPR and to λ = 721 nm LSPR accompanied by a general broadening of the SPR bands. This broadening can be explained by different chemical environments for diverse ligands and is a known characteristic for dual surfactant

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• metathesis to proceed efficiently “in water” [36]. Lipshutz and co-workers generalized the application of a three-component non-ionic surfactant for numerous reactions in water, including olefin metathesis [37][38][39]. The surfactant, PTS, incorporates α-tocopherol, sebacic acid and PEG moieties as part of

• by Lipshutz and co-workers for RCM and for CM reactions [40][41]. Scheme 6 displays the RCM of selected substrates with G-II as catalyst in the presence of PTS as surfactant. The work of Lipshutz and co-workers is extensively reported elsewhere [21][33][42][43]. Catalyst encapsulation is a recent

• overcome this challenge, a small amount of organic co-solvent (or surfactant) is frequently used. The removal of residual ruthenium traces is a crucial step for most industrial applications [45][46][47][48][49][50]. Indeed, the purification of products from metathesis reaction mixtures often requires

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• formation process [4][5]. In 2006, Long et al. reported a unique and innovative approach to produce fibers via electrospinning [6]. They focused on the association behavior of surfactant molecules as a function of the solution concentration and demonstrated that phospholipids (lecithins) in nonaqueous media

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-a]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium

• Nadia Bouzayani,
• Jamil Kraїem,
• Sylvain Marque,
• Yakdhane Kacem,
• Abel Carlin-Sinclair,
• Jérôme Marrot and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2018, 14, 2923–2930, doi:10.3762/bjoc.14.271

• -dione derivatives were obtained in good to excellent yields via the cyclocondensation of 2-formylbenzoic acid and various α-amino acid arylhydrazides using water as the solvent in the presence of sodium dodecyl sulfate as the surfactant and under simple and minimum manipulation, without purification

• mixture of hydrazide 3a and formylbenzoic acid 4 was heated at 120 °C (oil bath) using water as the solvent in the presence of SDS (10%) as the surfactant for 10 h leading to a 90% yield in 5a. To demonstrate the generality of this method, we next investigated the scope of this reaction under the

• above, we have never observed the formation of degradation products. (ii) The reaction was performed in water, in the presence of SDS (sodium dodecyl sulfate) as the surfactant. Based on previous studies [35], the most effective method for ensuring the solubility of reactants in water is the use of

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

• vesicles [41]. The inflection point in the plot of EY λmax vs surfactant concentration should be treated as the CAC of the amphiphile [42]. As can be seen from Table 1 the CAC values determined by the two methods are significantly different, especially in the case of macrocycles 10a,b. These differences

• are assigned to the different natures of the used dyes. In the case of EY, which is a dianion at pH 7, the interaction with the dicationic calixarenes 10a,b results in the formation of a non-charged complex, which can be referred to a non-ionic surfactant. Generally, non-ionic surfactants possess

• dicationic calixarene 10b with ADP results in an uncharged complex, which can be referred to a non-ionic surfactant. At the same time, binding of 10b with ATP affords a negatively charged complex (Table 2, entries 9 and 10). Obviously the formation of the uncharged complex of 10b with ADP increases the

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• their work, they also utilized an important chemical attribute of cetylammonium bromide (CTAB) – namely, CTAB forms surfactant-assembled lipophilic nanoreactors stable in organic solvents, which could be used for regioselective functionalization of indenes. Therefore, they investigated the

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• minutes residence time this corresponds to an O2-transfer rate of roughly 0.25 mM min−1. Similarly high values could be obtained previously only under mechanically demanding reaction conditions or using surfactant-stabilised emulsions [7]. Varying the ratio of gas to liquid had no significant effect on

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• possible to observe an hydrophilic and an hydrophobic face, giving to CA its characteristic surfactant properties. CA is sold as a treatment for children and adults affected by bile acids synthesis disorders. Because of its abundance in bovine bile, CA is the precursor for UDCA. CDCA 3α,7α-Dihydroxy-5β