In-depth characterization of self-healing polymers based on π–π interactions

• Josefine Meurer,
• Julian Hniopek,
• Johannes Ahner,
• Michael Schmitt,
• Jürgen Popp,
• Stefan Zechel,
• Kalina Peneva and
• Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

• °C for 17 h. After cooling to room temperature, water and chloroform were added to the mixture. The organic phase was washed two times with water, dried over sodium sulfate and concentrated. The residual was dissolved in tetrahydrofuran and dialyzed for three days with solvent exchange two times per

• to the mixture. The organic phase was washed two times with water and one time with brine, dried over sodium sulfate and concentrated. The residual was dissolved in a 1:1 mixture of chloroform and tetrahydrofuran and dialyzed for two days with solvent exchange two times per day (MWCO: 3500 g/mol

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• system equipped with an auto sampler system, a temperature-controlled pump, a column oven, a refractive index (RI) detector, a purge and degasser unit and a TSKgel superhZ2000, 4.6 mm ID × 15 cm × 2cm column. Tetrahydrofuran was used as an eluent at a flow rate of 1.0 mL/min at 40 °C. The refractive index

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• comprehensive combination of quantum mechanical calculations and experimental spectroscopic analysis of their NMR and ECD data, to have a unique tetrahydrofuran ring instead of the cyclopropane functionality. The absolute configuration of these five compounds were evaluated and all conserved as C6R, C1’S, C2’R

• (13) Sabitha and Raju demonstrated the first total synthesis of brevipolide M (13) in 2017 [17]. In the retrosynthesis, compound 93 is hypothesized from the Mitsunobu inversion at the C6’ stereocenter with (E)-p-methoxycinnamic acid (17) and ring-closing metathesis of tetrahydrofuran 93 (Scheme 11

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• effect of H2O (protic solvent) in the reaction media [48]. Pulido et al. had developed a conversion of allylsilyl alcohols 19 to diastereomeric mixtures of tetrahydrofuran derivatives 20A and 20B (Scheme 9) [47]. It was reported that more substituted alkyl groups present in allylsilyl alcohol 20b direct

• . Synthesis of β-ᴅ-arabinose derivative 18. Hg(OAc)2-mediated synthesis of tetrahydrofuran derivatives. Synthesis of Hg(TFA)2-mediated bicyclic nucleoside derivative. Synthesis of pyrrolidine and piperidine derivatives. HgCl2-mediated synthesis of diastereomeric pyrrolidine derivatives. HgCl2-mediated

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• ) hydroxylamine hydrochloride (21 mg, 0.300 mmol) was added. A clear solution was obtained shortly thereafter. The reaction was stirred for two hours at room temperature. Tetrahydrofuran (4 mL) and damp Raney-Nickel (approximately 200 mg) were introduced and the reaction was continued for one hour. The reaction

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• photoredox nickel-catalyzed arylation of α-oxy C–H bonds of tetrahydrofuran (THF) and oxetane were also shown. Further, the catalytic system also proved compatible for the C‒H arylation of the benzylic system. As shown in Figure 2 [54], the mechanism for the transformation is proposed to involve the

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• on the elemental analysis, the authors provided the formula representation C10H6(I2)0.4 for PAZ-I2 and C10H4.9(Br2)0.72 for PAZ-Br2. The gel permeation chromatography (GPC) analysis of the tetrahydrofuran (THF)-soluble fraction of PAZ-Br2 indicated the presence of oligomeric species (average degree

• polyazulene 3 or 3’ was soluble in various organic solvents such as toluene, dichloromethane, tetrahydrofuran (THF), and N,N’-dimethylformamide (DMF). The ‘true polyazulene’ exhibited the conductivity of 5.38 × 10−8 S/cm, which was increased to 8.16 × 10−3 S/cm upon exposure to iodine atmosphere, presumably

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

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• alkylindazoles. Initial screening of various conditions revealed that the combination of sodium hydride (NaH) in tetrahydrofuran (THF) (in the presence of an alkyl bromide), represented a promising system for N-1 selective indazole alkylation. For example, among fourteen C-3 substituted indazoles examined, we

• electrophiles, while maintaining a high degree of N-1 regioselectivity. Keywords: indazole; N-alkylation; regioselective; sodium hydride; tetrahydrofuran; Introduction Indazole (benzo[c]pyrazole) is an aromatic bicyclic heterocycle and can be viewed as a (bio)isostere of indole [1]. While only a few naturally

• 1H-indazole, employing NaHMDS in tetrahydrofuran (THF) or dimethyl sulfoxide (DMSO), and observed solvent-dependent regioselectivity [24]. Mechanistic hypotheses, based on elegant experimentation, were proposed to underline the roles that tight and solvent-separated ion pairs played in the observed

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• site-selective C(sp3)−H bond functionalization strategy (Scheme 28B) [160]. Starting from the abundant feedstock chemical cedrol, oxidation of the gem-dimethyl group was achieved on a gram scale, with the formation of a strained tetrahydrofuran ring. The latter was methylated and eliminated via the

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• fluorine activation (see 22i–j), and the oxygen-containing natural terpenoid ambroxide was methylated at the methylene position next to the O atom on the tetrahydrofuran ring (see 22k). This manganese-catalyzed late-stage approach enables the direct methylation of unactivated C–H bonds with excellent site

Organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones

• Chandrakanta Parida and
• Subhas Chandra Pan

Beilstein J. Org. Chem. 2021, 17, 1447–1452, doi:10.3762/bjoc.17.100

• enantioselectivities. A similar enantioselectivity was attained in α,α,α-trifluorotoluene and tetrahydrofuran as the solvent, whereas in chloroform a slightly improved enantioselectivity of 86% ee was observed. Finally, the best solvent was found to be 1,2-dichloroethane and the product 3a was obtained in 82% yield

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• -isobutyrylguanine, N-benzoylcytosine, 6-O-allylhypoxanthine or N,N-dibenzoyldiaminopurine in 53 to 83% yield. The desilylation of the nucleosides 3a–f with tetrabutylammonium fluoride in tetrahydrofuran (THF) led to the formation of six different double-headed nucleosides 4a–f (Scheme 1) [38][39]. The synthesized

• (Scheme 17) [54]. The tert-butyldimethylsilyl-protected (TBDMS) nucleoside 76 was first hydrolyzed using NaOH, which was followed by TBDMS deprotection using tetra-n-butylammonium fluoride (TBAF) in tetrahydrofuran (THF) to afford the double-headed nucleoside 77. The TBDMS-protected nucleoside 73 was

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• from the condensation reaction of aldehydes or ketones with tert-butanesulfinamides. In this work, the condensation with aldehydes was carried using Ti(OEt)4 in tetrahydrofuran (THF), or CuSO4 in dichloromethane at room temperature. The combination of MgSO4 in the presence of a catalytic amount of

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

• lines [59]. The synthesis was based on the reaction of commercially available aromatic amines with sodium dicyandiamide at 80 °C to obtain the corresponding aryldicyanoamides. The latter were then separately reacted with alkylamines or cycloalkylamines at 40 °C in tetrahydrofuran in the presence of

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

• 1,3-diaxial interaction, which favors the formation of tetrahydrofuran product 17 instead of the tetrahydropyran 16 (Scheme 4). Although the Prins cyclization is one of the powerful tools for the construction of 2,6-disubstituted THPs, there are some limitations that restrict a wide applicability. The

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases

• Naohiro Horie,
• Takao Yamaguchi,
• Shinji Kumagai and
• Satoshi Obika

Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54

• acetonitrile, dichloromethane, and tetrahydrofuran (THF) were used as purchased. 1H, 13C, and 31P NMR spectra were recorded using a JEOL JNM-ECS300 spectrometer. The chemical shift values are expressed in δ values (ppm) relative to tetramethylsilane as an internal standard, CHCl3 (δ = 7.26 ppm) for 1H NMR

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

• chirality of lactic acid, three forms of PLA (ʟ, PLLA; ᴅ, PDLA; ᴅʟ, PDLLA) with slightly different properties (crystallinity, Tg 60–65 °C, Tm 130–180 °C) exist [256]. PLA is soluble in benzene, tetrahydrofuran, ethyl acetate, propylene carbonate and dioxane [257], and it is biodegradable [258][259]. Because

Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system

• Yamato Fujihira,
• Yumeng Liang,
• Makoto Ono,
• Kazuki Hirano,
• Takumi Kagawa and
• Norio Shibata

Beilstein J. Org. Chem. 2021, 17, 431–438, doi:10.3762/bjoc.17.39

• effect on the yield of the reaction of 1g (Table 2, entries 3–6, 58–72%). Next, a range of common oxygen and sulfur-containing compounds such as furan, tetrahydrofuran, 1,4-dioxane, thiophene, benzo[b]thiophene, dibenzo[b,d]thiophene, and diphenylsulfane were also screened. These substances also have

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• alternating enantiomers form a screw along the a axis. Optical properties All helicenes 10 are well soluble in dichloromethane and chloroform. Solubility in other common solvents such as acetonitrile, DMSO, tetrahydrofuran, ethanol and hexane is markedly lower. Carbazole-based [6]helicene 12 was described as

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• environment responsiveness is based on having variable substituents at the para-position of the two phenyl moieties. The excited state properties were fully investigated in tetrahydrofuran (THF) solutions and in THF/H2O mixtures. The size of the aggregates in aqueous media were measured by dynamic light

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• = tetrahydrofuran, AD-mix-α = commercially available asymmetric dihydroxylation reagent, TBAF = tetrabutylammonium fluoride, DeoxoFluor = bis(2-methoxyethyl)aminosulfur trifluoride. Synthesis of compound 2 via a stepwise fluorination approach (ester series). DIC = diisopropylcarbodiimide, HOBt

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• procedure of Nishimura et al. using mercury acetate in trifluoroacetic acid and anisole as radical scavenger (Scheme 5) [34]. Cleavage of the tert-butyl protection group yielded the disulfide 1g, which was reduced with catecholborane in tetrahydrofuran to give the free thiol 1h, which readily reoxidizes

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• -(OAcG)6 exhibited good solubility in most organic solvents such as dichloromethane, chloroform, tetrahydrofuran, and DMSO, but it was insoluble in solvents like methanol, ethanol, and water. Compound TBTQ-(OAcG)6 was finally deacetylated with sodium methoxide in methanol to afford the desired six-fold

• -2,3,4,6-tetraacetylglucose (1.48 g, 3.96 mmol), copper(II) sulfate pentahydrate (52 mg, 0.21 mmol), and sodium ascorbate (28 mg, 0.14 mmol) in tetrahydrofuran/water cosolvent 2:1 (10 mL, v/v) was stirred vigorously under nitrogen in the dark at 60 °C for 24 h. Then, the solvent was removed under reduced