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

• same year, the same group developed a polystyrene resin-supported proline, which was confirmed to be highly suitable for continuous-flow setup whose efficiency and selectivity was highly stable over 30 hours of continuous runtime, allowing to isolate roughly 5 grams of pure aldol 68 (Scheme 9) [107

• proved to be less active. In 2013, the Knoevenagel reaction between benzaldehyde (17) and malononitrile was performed using a similar flow apparatus, however, using a polystyrene-supported DABCO as catalyst. Wang’s group confirmed the stability of the latter, which provides excellent conversions (95–90

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• excellent both in terms of enantioselectivities and conversions (up to 98%; up to 83% ee; Table 28). The reuse of the heterogeneous catalyst has not been studied in this case. In 2020, our group reported the first heterogeneous polystyrene-supported recyclable catalyst for the asymmetric conjugate additions

• first heterogeneous polystyrene-supported recyclable catalyst for asymmetric conjugate addition reactions of arylboronic acids to five and six-membered enones. In our laboratory, we also attempted to perform this reaction under flow conditions. However, the change from batch to flow arrangement itself

• /Pd(TFA)2 [53]. Addition reactions of arylboronic acids to 3-aryl-2-cyclohexenones catalysed by L9/Pd(TFA)2 [55]. Micellar nanoreactor for the synthesis of substituted flavanones [56]. Polystyrene-supported Pd complex PdL11 as catalyst for addition reactions of arylboronic acids to cyclic enones [57

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• production of biodiesel [5][80], intermediates for triazine synthesis [48], etc. Some derivatives were grafted onto polystyrene resins for catalytic uses [5]. Various solvents and temperatures were used such as hot DMF [5], neat [79], toluene or hexane at 25–100 °C [79]. Generally, higher temperatures seem

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• crystallinity, reduced chain mobility and hydrophobicity of polymers [114][115], which makes biodegradation often ineffective and time-consuming, particularly for polyolefins, such as polyethylene, polyvinyl chloride (PVC), polystyrene or PET [116][117]. Thus, abiotic pretreatments may be required, including UV

• Polystyrene (PS): PS is a low-cost, hard and brittle plastic used both as a solid or foam in protective packaging, containers and trays [151]. It is a nonbiodegradable material accounting for about 10% of municipal solid waste [135]. It is soluble in benzene, carbon disulfide, chlorinated hydrocarbons, lower

One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity

• Giovanna Bosica,
• Kaylie Demanuele,
• José M. Padrón and
• Adrián Puerta

Beilstein J. Org. Chem. 2020, 16, 2862–2869, doi:10.3762/bjoc.16.235

• general structure, corresponding to the 1,2-DHP regioisomer, unless when using aliphatic aldehydes. Experimental General All the chemicals used were purchased form Sigma-Aldrich. IR spectroscopy studies were conducted on a Shimadzu IRAffinity-1 FTIR spectrometer calibrated against 1602 cm−1 polystyrene

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• ° scattering angle with temperature controlled at 25 °C in 1 mL polystyrene cuvettes. Dex-1b was characterized in terms of size. Short time measurements were carried out for a total of 15 min, with three consecutive measurements for each sample. Transmission electron microscopy images were aquired by a JEOL

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

• from our own group include the synthesis of a polystyrene gel with a photocatalytic cross-linking monomer, 4,7-bis(4-vinylphenyl)benzo[c][1,2,5]thiadiazole (St-BTZ) [47]. Additionally, we showed the direct synthesis of a BODIPY photocatalyst as a postsynthetic modification to an aldehyde-functionalised

• postsynthetic modifications in flow [63]. Poliakoff, George, and co-workers reported a porphyrin photosensitiser ionically immobilised to sulphonate-cross-linked ion exchange polystyrene resins (amberlyst-15) for the synthesis of artemisinin (49). This resulted in a bifunctional material, which acts as a HPCat

• porphyrin colour from a purple powder to green when immobilised. The immobilisation of porphyrins onto polystyrene supports has been reported prior to this through covalent and electrostatic attractions but often suffered from poor coupling yields and low loadings [133][134][135][136]. Similarly, ionic

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• polystyrene, silica, glass, and others [4][5][6][7][8][9][10][11][12] generally leads to a deterioration of the catalytic properties of the initial homogeneous catalyst. This is due to factors including the nonhomogeneous structures of the catalytic centers on the surface of the carrier or inside the

• NDS and of one equivalent of TAPM at ambient temperature immediately produced F-1 as a white precipitate (Scheme 1). The pKa (in water) of NDS is expected to be −11 to −10, by analogy with the pKa of polystyrene sulfonic acids [12]. The four pKas of the conjugated acids of TAPM were calculated (see

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• aldehydes and ketones were studied in the photografting of acrylic acids. In 1988, Allméar and co-workers, while studying the grafting of acrylic acid (34) onto high- or low-density polyethylene and polystyrene using benzophenone as the photoinitiator and acetone (4) as the solvent, observed that the

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

Ugi reaction-derived prolyl peptide catalysts grafted on the renewable polymer polyfurfuryl alcohol for applications in heterogeneous enamine catalysis

• Alexander F. de la Torre,
• Gabriel S. Scatena,
• Oscar Valdés,
• Daniel G. Rivera and
• Márcio W. Paixão

Beilstein J. Org. Chem. 2019, 15, 1210–1216, doi:10.3762/bjoc.15.118

• ., polystyrene) [1][2][3]. When aiming at implementing large-scale catalytic processes with supported organocatalysts, a relevant “green” premise is the use of renewable and readily available solid supports [1][2][3][4][5]. Accordingly, we envisioned the utilization of the polymer polyfurfuryl alcohol (PFA

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• HPLC grade, Fisher) at 40 °C at 1.0 mL/min and calibrated using 14 monodisperse polystyrene standards (Alfa Aesar). The temperature was recorded using a Fluke VT04 Visual IR thermometer. Synthesis of trimethylene carbonate. 1,3-Propanediol (4.72 mL, 0.657 mol) and ethyl chloroformate (12.5 mL, 0.131

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

• of polystyrene resin 3 as the amine component. After resin removal with piperidine in DMF, a combinatorial strategy of replacing the carboxylic acid component with trimethylsilyl azide (TMSN3) (azido-Ugi reaction) or cyanic acid, followed by Fmoc removal (TFA), allowed the formation of the tetrazole

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• -permeation chromatography on the instrument Agilent Technologies 1260 Infinity with a refractive index detector, GPC/SEC – styrogel column, length 300 mm, internal diameter 7.5 mm, eluent (CHCl3) rate 1 mL/s, calibration according to the polystyrene standards known molecular weight. Thermal analysis was

Low-budget 3D-printed equipment for continuous flow reactions

• Jochen M. Neumaier,
• Amiera Madani,
• Thomas Klein and
• Thomas Ziegler

Beilstein J. Org. Chem. 2019, 15, 558–566, doi:10.3762/bjoc.15.50

• well [29]. Although 3D printing of reaction devices is a growing field in the last years, there are only a few examples of organic reactions with FDM-printed reactors [7]. Reactors made of materials like PLA, ABS (acrylonitrile butadiene styrene) or HIPS (high-impact polystyrene) are described in the

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

• Yuan-Zhen Ke,
• Shou-Ling Huang,
• Guoqiao Lai and
• Tien-Yau Luh

Beilstein J. Org. Chem. 2019, 15, 44–51, doi:10.3762/bjoc.15.4

• temperature at 40 °C using standard polystyrene samples (1.84 × 105 to 996 Da) for calibration. THF was used as eluent (flow rate 1.0 mL/min). Synthesis of 12. Under N2 atomosphere, to 10a (560 mg, 2.2 mmol) in DCM (20 mL) was added oxalyl chloride (0.4 mL, 4.3 mmol) at 0 °C. The mixture was gradually warmed

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

• Yo Hiranoi and
• Koji Nakano

Beilstein J. Org. Chem. 2018, 14, 2779–2788, doi:10.3762/bjoc.14.255

• polystyrene samples. The recycling preparative HPLC was performed with YMC-GPC T-2000 and T-4000 columns (chloroform as an eluent). HPLC analysis for determining the ee was carried out using a DAICEL CHIRALCEL® IA-3 column (4.6 mm × 250 mm). Synthesis of mono(salen) (R,R)-7: A Schlenk tube was charged with (R

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• substrate 14 followed by nucleophilic attack of the carbonyl moiety of carboxylic group. Furthermore, Giannis and co-workers [69] reported the synthesis of novel aminomethylpolystyrene-supported (diacetoxyiodo)benzene (PSDIB) reagents 17a and 17b starting from aminomethylated polystyrene with 4-iodobenzoic

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• this issue. A first solution has arisen from the development of polystyrene-supported reagents, which allows their recycling following simple filtration and re-oxidation (reaction 1 in Scheme 1a) [14][15]. More recently, the design of processes catalytic in iodine compounds has been extensively

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• absorption abilities towards charged guests can be evidenced, due to the possible protonation of the triazole linker subunits. As a final remark, it is worth noting here that, although the well-known hyper-reticulated polystyrene polymers [48][49] have been occasionally addressed to as “nanosponges” [50

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• for facile tuning of their properties such as size [13][74], membrane permeability [75] and stability [76]. Various copolymers have been reported for polymersome formation such as poly(ethylene glycol)-b-polystyrene (PEG-b-PS) [14][77], polystyrene-b-polyisocyanopeptide (PS-b-PIAT)[21][22] and poly(N

• recycling. Polymeric nanoreactors were also used to perform ring-opening polymerization (ROP) in water. Nallani et al. reported on the enzymatic polymerization of lactones using CalB, which was immobilized in both the polymersome lumen and bi-layer [21]. Nanoreactors for ROP were prepared from polystyrene

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• polystyrene, 2% cross-linked with divinylbenzene (PS-C6H4-PPh2) was obtained from Biotage® and used without further purification. Benzaldehyde was obtained from Sigma Aldrich and used without further purification. Alkyl halides and carbonate bases were obtained from Fisher Scientific and used without further

Preparation of trinucleotide phosphoramidites as synthons for the synthesis of gene libraries

• Ruth Suchsland,
• Bettina Appel and
• Sabine Müller

Beilstein J. Org. Chem. 2018, 14, 397–406, doi:10.3762/bjoc.14.28

• polystyrene support decorated with a photolabile linker and its potential use for the synthesis of siRNA duplexes under mild and neutral conditions [36]. A similar strategy was used for the synthesis of partially 2'/3'-O-acetylated RNA oligonucleotides [37]. A photo-cleavable linker would also have potential

• lab, we have been developing a strategy for solid-phase trinucleotide synthesis involving a disulfide linkage to the support (CPG or polystyrene), which can be cleaved under reductive conditions without harming nucleobase and phosphate protecting groups. The disulfide bridge is generated through the

• reaction of a 3'-O-methylthiomethyl-functionalized nucleoside with 2-mercaptopropionic acid and subsequent coupling to amino-functionalized CPG or polystyrene. After assembly of the trinucleotide on the support, the disulfide bridge is cleaved by treatment with dithiothreitol (DTT) [38] or tris-(2

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• to combine the electron-donating 9,9-dimethyl-10-phenylacridan with the electron-accepting 2,4,6-triphenyl-1,3,5-triazine was reported under the form of random copolymers derived from a polystyrene (T31–T34, see Figure 9) [60]. Contrarily to the classical TADF materials in which the electron donor is

• -bis(3,5-di-tert-butylphenyl)-10-phenylacridan. Precisely, effect of the steric hindrance on TADF properties of the polymers was investigated by introducing a steric hindrance on the electron donor. Use of polystyrene to generate EL materials is counterintuitive due to its inherent insulating character

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• probe. One of the earliest examples makes use of PNA probes immobilized on fluorescence-polymer-coated polystyrene microspheres and a quenching DNA strand [106]. The fluorescence of the microsphere was restored upon displacement of the quencher DNA strand by the DNA target in a sequence-dependent manner

• following standard surface-hybridization protocols. The use of the solid support assay format also allows detection of DNA directly from the fluorescence signal of the CPP bound to the solid support without requiring labeling on the PNA probe [126]. Polystyrene microbeads self-assembled on patterned silicon