Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

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

• achieved with self-initiated photografting and photopolymerization (SIPGP, Scheme 1). SIPGP is a simple, solvent-free bulk/surface photografting first introduced by Deng et al. grafting maleic anhydride [20] and styrene [21] onto low-density poly(ethylene) films. Later, this was extended for other monomers

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

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• from MZ-Gel SD plus, 500 A and 100 A, linear 5 µ; UV detector (SPD-20A) and RI detector (RID-20A)) using THF as eluent. Poly(styrene) standards in the range of 350 to 17800 g/mol purchased from Polymer Standard Service were used for calibration. Computational details All calculations were run with the

• –Currier repeat units; right: size exclusion chromatograms (in THF, relative to poly(styrene) standards) of poly4 prepared with 5 mol % TPP, MMTPP or TMTPP using a reaction time of 24 h and a reaction temperature of 23 °C (dashed lines) or 80 °C (full lines). Left: Oxidation stability of the phosphines

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

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• ., styrene derivatives [17]) that produce hundreds of tons for polymer synthesis. The goal of this review is to demonstrate the utility of olefins as starting materials in the synthesis of all-carbon quaternary centers through hydroalkylation reactions. Only the hydroalkylation of unactivated olefins as

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• vinylboronate afforded the o-hydroxyethyl-styrene 12a in 78% yield [22][23]. Next, Dess–Martin oxidation of the alcohol 12a was carried out, and the desired 2-(2-vinylphenyl)acetaldehyde (13a) was successfully obtained in 85% yield. Obviously, this modified method has the advantages of mild reaction conditions

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

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• the synthesis of diol by the condensation of styrene and paraformaldehyde in the presence of a Brønsted acid [23][24]. The major breakthrough for this reaction was reported by Hanschke in 1955, when the THP ring was selectively constructed through a Prins reaction involving 3-butene-1-ol and a variety

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• trifluoromethylation (Scheme 25). A variety of olefins, such as ene carbamates, styrene, aliphatic olefins, vinyl ethers, and acrylates are compatible in this approach, affording corresponding β-(trifluoromethyl)alkynes with good to excellent yield. The bifunctionalization was achieved by an EDA-complex-initiated

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

• °C provided a hydrocarbon oil in 92% yield, 71.4% of which were attributable to styrene monomer [156]. A decrease of 56 kJ mol−1 for the activation energy of PS depolymerisation was calculated in the presence of the catalysts. More recently, high-porosity montmorillonite (Mt) was used to prepare Mg

• -, Zn-, Al-, Cu- or Fe-decorated heterogeneous catalysts [157][158]. An oil yield around 89% was obtained at 450 °C over 20% Fe@Mt, composed by 51%, 10% and 6% (wt) styrene, toluene and ethylbenzene, respectively, and additional oligomers. 3.2 Polyesters 3.2.1 PET: PET is one of the most widely used

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• the oxidant agent. Among the reported methods that make use of peroxides as oxidants, cobalt nanoparticles supported on CNTs together with TBHP as oxidant for the epoxidation of styrene, gave good selectivity to styrene oxide but conversions were lower than 40% [41]. More recently, Hutchings et al

• suspension was stirred for 2 h (see Experimental for details). The CoNPs-based catalysts were ready for use after filtration and drying in an oven at 150 °C for 1 h. Styrene (1a) was chosen as model substrate for testing the activity and selectivity of a variety of CoNPs-based catalysts (Table 1). The

• the CuNPs supported on MgO as catalyst, but a similar result to that obtained in DMF was observed (Table 1, entry 5). The use of H2O2 as co-oxidant improved the conversion of the starting styrene (1a) only for the CoNPs/MgO catalyst, but lead to low selectivity due to the formation of benzaldehyde and

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• alkenes, electron-rich styrenes, and styrenes with electron-withdrawing substituents in the structure [40]. The yields of the gem-difluorocyclopropanes from the styrene derivatives were almost all excellent. On the other hand, simple alkenes gave lower yields. The reaction of various functionalized

Au(III) complexes with tetradentate-cyclam-based ligands

• Ann Christin Reiersølmoen,
• Thomas N. Solvi and
• Anne Fiksdahl

Beilstein J. Org. Chem. 2021, 17, 186–192, doi:10.3762/bjoc.17.18

• cyclopropanation of styrene with propargyl ester [49][50][51][52] (Table 1) were selected as test reactions. These reactions have previously been studied with different gold(I) and gold(III) catalysts and a variety of substrates, thus providing a solid background for comparison. A large difference in the catalytic

• diamides 1a,b and tetraamides 2a,b. Au(III) coordination conditions for ligands 5a,b and 6a,b. Coordination of 5b was unsuccessful. The catalytic activity of Au(III) complexes evaluated in a) alkyne carboalkoxylation and b) cyclopropanation of styrene with propargyl ester. Supporting Information

Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256

• styrene [48][49][50]. We envisioned that it could be possible to replace the Et3B in Dolbier’s protocol by a stable amine–borane complex that could perform the radical initiation of SF5Cl on its addition on alkenes. This would address the drawbacks associated with the use of Et3B as the radical initiator

• reactions on styrene, the desired addition product 2c was only observed with a low NMR yield of 8% with the Et3B-mediated reaction, while the DICAB protocol led to a 15% isolated yield of the 2:1 addition product 2d, with no sign of the desired compound 2c. Furthermore, as expected, a low yield of 15% of

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• ] cycloaddition reactions [45]. Thus, while styrene and maleic anhydride react only at elevated temperatures, with the more electrophilic (methoxycarbonyl)maleic anhydride two 2:1 adducts are already formed at room temperature: one by two consecutive Diels–Alder reactions, the other one by a Diels–Alder/ene

• reaction of propyn-1-iminium salt 1a with styrene in acetonitrile was considered first and was monitored by 19F NMR spectroscopy. Whereas no reaction appeared to occur at room temperature, a slow transformation into two fluorine-containing products was observed at 70 °C, which after neutralization and work

• reaction mechanism. Thus, the reaction of 1a with α-methylstyrene or 1,1-diphenylethene proceeded at a faster rate than with styrene and yielded 3-methyl- and 3-phenyl-2-vinylindenes 12b and 12c (structure confirmed by an XRD analysis, see Figure 2) in high yields. Benzo[a]fluorenes were found to a minor

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• ), respectively (Table 2). These results show that the relative configuration is preserved. 4-Phenyl-1,3-dioxolan-2-one (8f) and 4-phenyloxazolidin-2-one (9f) were obtained from the reaction of CSI with styrene oxide (7f) showing the regioselective nature of the reaction. In addition, we report the synthesis of

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

• the efficiency of synthesising and purifying immobilised photosensitisers [63]. A BODIPY photosensitiser was immobilised to an aldehyde-functionalised Merrifield resin (poly(styrene-co-divinylbenzene-co-4-formylstyrene)) in continuous flow and concurrently in an analogous batch procedure. The coupling

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

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

• . Huang and co-workers proposed a polar radical crossover cycloaddition mechanism for this Diels–Alder cycloaddition (Scheme 6). The electron transfer from the electron-rich styrene 14 to the activated acridinium photocatalyst 15 oxidizes the styrene 14 to form the styrene radical 16 and the acridine

• radical 17 (Mes–Acr–Ph•). The subsequent reaction of the formed styrene radical 16 with another styrene 18 gives the radical species 19 and the reoxidation of the acridine radical 17 by a thiyl radical, which is generated by the homolysis of diphenyl disulfide, regenerating the photocatalyst. In a

• hydroxylation product 36 and frees the disulfide for the next cycle. The generation of the disulfide–olefin complex 37 from styrene and disulfide initiates the hydroxymethylation. The following 3O2 trapping by the intermediate 38, which is generated by the addition of a thiyl radical to the styrene under

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• , produced exclusively thietane derivatives 240 and 241 [70] (Scheme 45). The authors further investigated photoreactions of N-substituted monothiophthalimides 237 with styrene derivatives 186 and 242, affording the corresponding spirothietanes 243 and 244 [71] (Scheme 46). They also documented the

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 free radicals (Scheme 9). It remains unchanged [45] when dissolved in styrene (2 hours, 25 °C) or vinyl acetate (20 minutes, 60 °C; conversion of the oxime radical was less than 10% after 3 days at 25 °C). The inertness of the di-tert-butyliminoxyl radical with respect to the mentioned substrates

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• undergo a photoexcitation, leading to the excited state that can then oxidize the thiolate and generate the key S-centered radical. The latter then adds to the styrene

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

• styrene oxide (2) with methanol. Within 1 hour at room temperature, the alcohol 3 was obtained in a quantitative yield and as a single regioisomer (Table 1, run 2). The CAHOF F-1 was robust and retained the catalytic activity after being recovered from the reaction mixture five times (Table 1, run 3). In

• contracted and expanded their pores in the presence of guest gases [42]. In the limiting case, the framework may even become partially dissolved in a polar solvent. The CAHOF F-1 was also catalytically active for the conversion of styrene oxide (2) into the diol 4 (Table 1, runs 8–14). This reaction was a

• efficiency of the reaction dropping as the size of the alcohol was increased and its polarity decreased (Table 2, runs 1–3). Water could also be used as the nucleophile (Table 2, runs 4 and 5) and led to the trans-cyclohexane diol 6 under the same experimental conditions used for the styrene oxide ring