A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• dehydration to give the heterocyclic product 3. At the cathode, protons are reduced to release H2. Conclusion In conclusion, we have developed a one-pot electrochemical strategy for the synthesis of 2-amniothiazoles by the reaction of active methylene ketones with thioureas. The electrochemical synthesis was

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• approach have already been realized. For example, some metallopolymer-based systems now enable a controllable release of metal ions by ultrasonication to trigger or catalyze small molecule reactions in solution [16][17][18]. Complementarily, studies on mechanically releasing cargo and unmasking

• -workers found that ball milling of the cross-linked polyacrylate polymer 1 could trigger the release of singlet oxygen from the anthracene–endoperoxide mechanophores (Scheme 1a) [27]. To support the claim that the generation of 1O2 occurred mechanically rather than thermally due to local heat formation by

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• bond to N atom (Scheme 4). This process is thermodynamically favorable by a Gibbs free energy (ΔG) of −6.5 kcal·mol−1. In addition, a second way from 4a, through the TS5 transition state, to form the IS3 intermediate requires an activation energy of ca. 33.7 kcal·mol−1. IS3 could release one H2O

• from two –OH groups close together (blue line). Another competitive direction is from 4a to IS3 and finally to 10ab-v2 by the release of one H2O molecule from O–H and N–H groups. Noticeably, in the ethanol solvent model, the formation of 10ab and 10ab-v2 is thermodynamically similar (the ΔG difference

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• anti-inflammatory activity by the inhibition of LPS-induced TNF-α and CCL2 release in RAW 264.7 macrophages. Keywords: Acanthella cavernosa; anti-inflammatory; biosynthetic pathway; chiral separation; marine sponge; sesquiterpenoid; Introduction Marine sponges of the genus Acanthella (class

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• maximum in the magnetic field, 2) the remanent magnetization (Mr), which is retained by the material when the magnetic field is removed, and 3) the coercivity (Hc), which is the magnetic field required to demagnetize the sample and determines the heat release to the surrounding media. These three

• parameters are critical to the heat release of magnetic nanoparticles and can vary for different particle types. Coercivity is an inherent property of magnetic nanoparticles that reaches a maximum at a critical diameter of magnetic nanoparticles from multidomain to single domain structures. In hysteresis

• remarkable application for inductive heating. 2.4 CO2 storage and release under RF heating The climatic changes are associated, among other factors, with increasing emissions of CO2 into the atmosphere. The group of Rebrov et al. investigated the storage of CO2 in CaO via the calcination process using

Rapid gas–liquid reaction in flow. Continuous synthesis and production of cyclohexene oxide

• Kyoko Mandai,
• Tetsuya Yamamoto,
• Hiroki Mandai and
• Aiichiro Nagaki

Beilstein J. Org. Chem. 2022, 18, 660–668, doi:10.3762/bjoc.18.67

• performing the reaction in a continuous flow system. To the best of our knowledge, this is for the first time to achieve the epoxidation of cyclohexene using air within only 1.4 min by carefully avoiding any unwanted release which could result in a hazardous situation. In our flow conditions, the volume of

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• replicating their structures). The structural dissimilarity between the reactants and the subsequent product often contributes to the successful release of the product from the reaction vessel, thus, reducing product inhibition. Hence, it can be envisioned that the introduction of functionality within the

• release 89 into solution. Indeed, now the catalysis of addition product 97 was turned ON. While supramolecular transformations are widely recognized [101][102][103], the present example illustrates how a supramolecular catalyst (three-component rotor) transforms itself into a new catalytic machinery and

• stabilized within the catalytic cavity. Release from the active site then requires destruction of the stabilizing interactions. For instance, Nature has chosen in the ATP-synthase to use “fueled” nanomechanical motion to release ATP from the active site [23]. Switchable catalysis due to reversible assembly

Synthesis of a new water-soluble hexacarboxylated tribenzotriquinacene derivative and its competitive host–guest interaction for drug delivery

• Man-Ping Li,
• Nan Yang and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2022, 18, 539–548, doi:10.3762/bjoc.18.56

• derivative with an extended cavity that can associate with anticancer drugs through host–guest interactions. The resulting host–guest complexes can be considered as camouflaged anticancer drugs that may exhibit low or no cytotoxicity in normal cellular environment. Furthermore, it is hoped that the release

• competitive guest to control the release of MV and DOX. The structures of the target molecule TBTQ-CB6 and its precursors were characterized by NMR spectroscopy and mass spectrometry. The host–guest chemistry of TBTQ-CB6MV, TBTQ-CB6DOX and TBTQ-CB6SM was investigated by NMR spectroscopy and fluorescence

• should give SM a competitive binding advantage to TBTQ-CB6 and, therefore, enable the release of MV and DOX from TBTQ-CB6MV and TBTQ-CB6DOX complexes. Competitive replacement of MV from the TBTQ-CB6MV complex by SM. 1H NMR titrations [20] were performed to characterize the competitive binding process of

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• formation of phenoxyhydroxyketone 4 proceeds via 1,3-dioxolan-2-one 6 generated from bromopropargylic alcohol 1 and Cs2CO3. Then, Br-substitution/hydration of 6 and the release of CO2 give product 4 (Scheme 7). Apparently, diphenoxyketone 5 results from decarboxylative conversion of 1,3-dioxolan-2-one 7

Trichloroacetic acid fueled practical amine purifications

• Aleena Thomas,
• Baptiste Gasch,
• Enzo Olivieri and
• Adrien Quintard

Beilstein J. Org. Chem. 2022, 18, 225–231, doi:10.3762/bjoc.18.26

• formation of protonated amines which evolve spontaneously over time back again to the neutral amine upon release of CO2 from the initial acid. Among the potential acids available for such processes, trichloroacetic acid (TCA) has been used to fuel different supramolecular switches [6][7][8][9][10]. This

• equilibrium supramolecular machinery through a temporary protonation returning to the initial state upon time [3][4][5]. While conceptually interesting, in terms of laboratory practicability, it would be desirable to have a faster release of the free amine. For this purpose, a small amount of volatile base

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• ) and PGE2 in alveolar macrophages. Then, oximes 46a,b and 48b were obtained by condensation of 45a,b and 47b with hydroxylamine, respectively. Biological results indicated that 47b significantly attenuated the release of inflammatory mediators (NO, TNF-α, and MMP-9) in a concentration-dependent manner

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• ) provide entry into similar photo-uncaging chemistries for amide release. Figure 1C shows an example of this concept applied to a peptide substrate. Reaction of the peptide i with an alkenylboronic acid reagent iv in the presence of a copper(II) salt in water provides access to the backbone N–H

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• produce the pyrrolidinyl methyl radical 10 which may add to the iron center to form the Fe(III) complex 11. Reductive elimination would give rise to the final product, and transmetallation with a Grignard reagent regenerates the active Fe species. Alternatively, release of the aryl radical via ipso-attack

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• (CPE) was investigated using single-crystal X-ray diffraction spectroscopy, isothermal titration calorimetry (ITC) and UV–vis, NMR and IR spectroscopy. The effects of Q[8] on the stability, in vitro release performance and antibacterial activity of CPE were also studied. The results showed that CPE and

• Q[8] formed a 1:1 inclusion complex (CPE@Q[8]) with an inclusion constant of 5.474 × 105 L/mol. The intervention of Q[8] did not affect the stability of CPE, but obviously reduced the release rate of CPE in artificial gastric and intestinal juice; Q[8] has a slow-release effect on CPE. The

• inhibitory activity of CPE against E. coli. Keywords: antibacterial activity; chloramphenicol; cucurbit[8]uril; host–guest interaction; in vitro cumulative release; stability; Introduction Chloramphenicol (CPE, Figure 1A) is a broad-spectrum antibiotic resulting from the metabolism of chorismic acid in

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

• ), as functional groups on the polymer chains can have weak acidic characteristics if they release protons, or weak basic characteristics if they accept protons, in response to changes in pH. This can come about from even small variations in solution pH, depending on the degree of ionisation and pKa

• great range of pH changes are faced when a foreign material travels through the human system. For example, for an orally administered drug-delivery device to release therapeutic agents in the colon, it must withstand a range of conditions as it passes through the body, including pH 6.2–7.3 in the mouth

• . Furthermore, a response to pH can be utilised to release the therapeutic agent at a site of specific acidity, thus ensuring targeted delivery. Poly(acrylic acid)-based cryogels have been investigated as a pH oscillator in oscillatory bromate-sulphite-ferrocyanide reactions as potential soft materials for

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• release of a nitrogen molecule to form the desired product 46. In 2018, Ding and co-workers reported the synthesis of 2-tetrazolyl-substituted 3-acylpyrroles 53 via sequential Ugi-azide/Ag-catalyzed oxidative cycloisomerization reactions in good yield (Scheme 20) [64]. Firstly, The Ugi-azide reaction

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• neuroprotection activity by measuring the secretion of NGF from C6 cells into the medium (Table 4). Compounds 8 and 16 stimulated NGF release, exhibiting stimulation levels of 134.2 ± 8.1% and 134.6 ± 5.9%, respectively. Although compounds 3 and 8 have similar structures without or with a methoxy group at C-5

• the MTT assay. Measurement of NGF secretion and cell viability assays. C6 glioma cells (Korean Cell Line Bank, Seoul, Republic of Korea) were used to measure the release of nerve growth factor (NGF) into the culture medium. The C6 cells were seeded onto 24-well plates at a density of 1 × 105 cells

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• investigate the transferability of this concept to our system, the light source was changed to blue LEDs. This change seemed to increase reactivity, observed by significantly more vigorous nitrogen release, resulting in shortening of the reaction time to 2 h. The reaction yield on the other hand was slightly

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

• class-I riboswitch [1]. This riboswitch acts as a ribozyme by using 7-aminomethyl-O6-methyl-7-deazaguanine (m6preQ1) as methyl group donor; it catalyzes self-methylation of a specific cytidine in the aptamer binding pocket, yielding N3-methyl cytidine (m3C) under release of 7-aminomethyl-7-deazaguanine

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

• (III) species 4-IX, which undergoes reductive elimination to release the desired product 10a. Concurrently, Molander and co-workers also reported a related nickel-catalyzed arylation of α-heteroatom-substituted or benzylic C(sp3)‒H bonds by aryl bromides 3 at room temperature using an iridium

• the excited photocatalyst to the 5-IV complex resulted in excited 5-V. Subsequently, the homolysis of the Ni–Br bond in 5-V followed by a HAT process results in species 5-VI. The nickel–alkyl–aryl complex 5-VI undergoes reductive elimination to release the desired product 10a and regenerates the

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

• . If this condition is fulfilled, solvation of the polymer takes place. First, cohesive forces between the solvent molecules and the polymer chains must be overcome. At the same time, polymer chains come into contact with solvent molecules, which leads to the release of solvation energies or adhesion

• , the developed GA-polyHMPA initially exhibits UCST responsiveness, but can subsequently be slowly biodegraded to a fully water-soluble polymer (polyHMPA) via hydrolysis. Initial in vivo studies of a sustained release of either a hydrophilic model protein or a hydrophobic dye entrapped within the

• (AAm) and the hydrophobic AN block [51][52][94]. Since the phase transition temperature of the copolymer can be adjusted over a wide temperature range via the ratio of the two monomers, it is frequently used for the development of novel drug release systems [272][273][274][275][276]. Due to the

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• . Polymerization of an acrylate-based monomer causes the release of heat from each polymerizing double bond (−83.6 kJ/mol) [19]. This allows an exothermic reaction in different systems based on the reactivity but also due to the heater behavior of the NIR dye, i.e., a high light-to-heat (photothermal) conversion

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

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

• , which via a gold catalysis can be triggered to release the drug on specific sites of the target cell in a controlled manner (Scheme 15A) [123]. A proposed catalytic cycle based on kinetic isotopic effect and kinetics data is illustrated in Scheme 15D. At the beginning of the reaction, intermediate III

Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

• Christin Walther,
• Pamela Baumann,
• Katrin Luck,
• Beate Rothe,
• Peter H. W. Biedermann,
• Jonathan Gershenzon,
• Tobias G. Köllner and
• Sybille B. Unsicker

Beilstein J. Org. Chem. 2021, 17, 1698–1711, doi:10.3762/bjoc.17.118

• volatiles known from the literature to mediate plant–insect interactions. Of the 13 endophytes studied, 11 of them release volatiles previously reported from black poplar foliage (Table 2) [57][58][59]. These compounds include the alcohols 3-methyl-1-butanol (6) and 2-phenylethanol (3) and the