Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• protons of –N–CH2-CH2–Ph. A singlet peak at δ 1.86 is attributed to methyl protons on the imidazole ring. The 19F NMR spectrum of 1H-1,2,3-triazole compound 5c showed a singlet at δ −113.61 corresponding to one fluorine atom of the phenyl ring. The high-resolution mass spectrometric data at 317.1141 (M

• aromatic protons of the phenyl ring. A singlet signal at δ 7.95 is for the 1H-imidazole proton. Two doublet signals at δ 4.73 and δ 4.71 are assigned to the four methylene protons of –N–CH2-CH2–Ph. A singlet peak at δ 2.48 is due to the methyl protons on the imidazole ring. The high-resolution mass

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

• washed with tap water, the cells were stained with 0.4% SRB solution and incubated for 30 min at room temperature. These cells were washed to remove the unbound dye and subsequently solubilized with 10 mM unbuffered Tris base solution (pH 10.5). The absorbance was measured spectrophotometrically at 520

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• ((4-carboxybutyl)triphenylphosphonium bromide), which was chosen as a target agent for the herein conducted studies, and covalently coupled to PPM-NP and MPM-NP particles. The reaction was conducted in aqueous medium, using 5 equiv excess of TPP-COOH to RAFT-end group. The pH was first adjusted to 5.2

• mmol, 5 equiv to RAFT end group) and N-hydroxysuccinimide (NHS) (0.025 mg, 0.00022 mmol, 5 equiv to RAFT end group) were added (stock solutions were made in Milli-Q water and 25 µL of stock solution were added accordingly). The pH was corrected to 5.2 using 0.1 M NaOH or 0.1 M HCl solution. The

• solution was stirred for 45 min and the pH was adjusted to 8.3 and the solution was stirred for 3 days at room temperature. The particles were purified by dialysis in Milli-Q water with frequent solvent change (regenerated cellulose membranes, MW cut-off 6000–8000 g mol−1) and analysed via DLS experiments

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• chromosome known as Philadelphia (Ph). Ph is the result of the reciprocal chromosomal conversion between the proto-oncogene Abl1 of chromosome 9 and the BCR gene on chromosome 22 [3][4]. Research activity on compounds able to act as protein tyrosine kinase inhibitors (TKIs), which has intensified since the

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• used in pH-sensitive fluorescent materials [10] and laser technologies [11][12][13][14]. Moreover, xanthenes are present in some natural sources, such as santalin pigments found in many varieties of plants [15][16]. There have been many studies on the synthesis of xanthene derivatives to date because

• synthesized by Grignard reaction of 1a–l and aryl(or alkyl)magnesium bromides. Then 3a–l were prepared by oxidation of 2a–l using PCC. The final alkene compounds 4a–l were obtained by Wittig reaction using Me(Ph)3PBr, t-BuOK, and NaH. All substrates were purified by crystallization or column chromatography

• , K2CO3, DMF, reflux, 2 h, 91%; (ii) PhMgBr, dry THF, 0 °C, 2 h, 86%; (iii) PCC, CH2Cl2, rt, 2 h, 80%; (iv) Me(Ph)3PBr, t-BuOK, NaH, dry THF, rt, 3 h, 85%. Plausible reaction mechanism for the cyclization reaction of alkene 4a. Screening of catalysts for intramolecular FCA of 1a.a Exploration of solvents

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• .) 0.2%, NaCl 0.2%, CaCO3 0.1%, and agar 1.5% in distilled water of pH 7.0) was inoculated into a 500 mL K-1 flask containing 100 mL of the V-22 seed medium (soluble starch 1%, glucose 0.5%, NZ-case 0.3%, yeast extract 0.2%, tryptone (Difco Laboratories) 0.5%, K2HPO4 0.1%, MgSO4·7H2O 0.05%, and CaCO3 0.3

• % in distilled water of pH 7.0). The flask was shaken on a rotary shaker (200 rpm) at 30 °C for 4 days. For the production of nomimicins B (1) and C (2), the seed culture (3 mL) was transferred into 20 500 mL K-1 flasks, each containing 100 mL of the A16 production medium (glucose 2%, Pharmamedia

• (Traders Protein) 1%, CaCO3 0.5%, and Diaion® HP-20 (Mitsubishi Chemical Corporation) 1% in distilled water of pH 7.0). The inoculated flasks were placed on a rotary shaker (200 rpm) at 30 °C for 7 days. For the production of nomimicin D (3), the seed culture (3 mL) was transferred into 20 500 mL K-1 flasks

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

• ideal chemical components for the generation of smart devices. Depending on the polymer structure, including backbone and functional groups [10], their properties can be reversibly influenced by external chemical (e.g., pH value [11][12], ionic strength [13], polarity of solvent [14]), biological (e.g

• the underlying thermodynamic mixing theory. However, although the influence of certain molecular parameters such as chain length, concentration, pH or low molecular weight additives are discussed, the thermoresponsive behavior of polymers is exclusively considered as free polymer chains in solution

• observed by, e.g., zeta potential measurements. Two scaling regimes can be defined as limiting cases using the specific localization of the counterions that results from additionally added salt: the salted brush and osmotic brush [136][137][138]. These additional counterions, in addition to pH changes

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• incompatible with either base-sensitive or acid-sensitive substituents, as the desired SMAHOs are isolated after acidification to pH ≤ 2. It was thus impossible to prepare reagents bearing a phthalimide, an ester or an acetal group. This limitation is overcome by the other possibilities afforded by this

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

• , 11 of them were never synthesized before. Markedly, noncharged structures, negatively charged cyanine bearing Na+ as counter cation, and positively charged cyanines bearing (B(Ph)4−) or (I−) as counter anions were examined as promising NIR light photoinitiating systems. Excellent photoinitiating

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• isoxazoline ring shields the vinyl group at C-4 from reacting with the bulky catalyst molecules (Figure 4). For the smaller Me or Et groups, this effect is relatively weak (only some reactions of (±)-5 with 7c and 7e were completely regioselective). The large Ph group, however, provided complete

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

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

• seems to favor N-1 regioisomer formation in the order t-Bu > Ph > Me > H, for both conditions A and B (Table 2, entries 1–4). Furthermore, having a sterically demanding t-Bu group at the indazole C-3 position (14) gave the N-1 substituted regioisomer 29 exclusively under both conditions A and B

• regioisomeric N-1/N-2 distribution indicated that steric bulk likely plays a significant role in determining N-1 regioselectivity. For example, the ratio of N-1/N-2 increases in the order of increasing steric bulk at the indazole C-3 position (H < Me < Ph < t-Bu). However, when the former protocol (conditions A

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

• have been used as additives in these reactions and are suggested to act as ligands, assist proton transfer and promote the formation of oligovanadates by decreasing the pH value of the solution. The mechanisms of some vanadium-mediated oxidation reactions of alkanes have been studied, most of them

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• incorporated into TFOs all induced excellent triplex stability at pH 7.0 [94] (Table 6). To circumvent the laborious work related to the monomers described above, post-ON conjugation via click-chemistry was utilized to attach two different spermidine analogues, carrying either two (56) or three (57) positive

• ’-aminoalkylated-LNA monomers [94]. The triplex stability of the monomers was determined, and the spermidine variant carrying three cationic charges (57) had the highest triplex stabilizing effect [95]. Interestingly, at biologically relevant pH (7.0), two incorporations of the nor-spermidine variant (53) [94

• - (monomer 71) and N-methyl-2-(dimethylamino)ethyl (monomer 72) phosphoramidate linkages [106]. How these N-alkylated phosphoramidate-linked ONs interacted with the complementary DNA was highly dependent on the ionic strength and the pH of the relevant medium. An inverse effect between hybridization

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

• the GT concentration at sub-lethal levels via redox cycling and S-methylation of active disulfides in GT, respectively [117][118]. Furthermore, in terms of exogenous factors, not only GT itself but several other biotic and abiotic factors, including neutrophilic granulocytes, media composition, pH

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

• species tested in our study (Table 2). However, the differences in the literature may arise from the use of different strains, volatile collection methods or variation in age, growth medium and environmental conditions, such as moisture, pH, temperature, and nutrient levels, or co-cultivation [27][41][67

• diameter) growing on PDA. The mycelium was flash frozen in liquid nitrogen and ground using plastic pestles in 1.5 mL Eppendorf tubes. After homogenization of the mycelium, 500 µL extraction buffer (100 mM Tris HCl, pH 8; 10 mM EDTA, pH 8; 2% w/v SDS) and 100 µL proteinase K (Sigma) were added and the

• rpm (10 min), dried, and finally dissolved in 50 µL Milli-Q water (pH 6). DNA concentration and purity were determined with a NanoDrop 2000c spectrophotometer (Peqlab Biotechnology AG, Erlangen, Germany). The primer pair ITS1F and ITS4 (Supporting Information File 1, Table S2) was used to amplify the

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

• [1]. Even with the additional lysine, the solubility of PNA decreases as the polymer length increases. PNA solubility in the HEPES buffer at pH 7.3 and 37 °C is estimated to be in the 0.1–0.5 mM range [12][13]. The hydrophobic nature and lack of electrostatic repulsion of the PNA backbone favors

• Rozners and co-workers showed that PNAs as short as hexamers formed strong and sequence specific triplexes at pH 5.5 [27]. Later studies using nucleobase-modified PNA (vide infra) confirmed that PNA had >10-fold higher affinity for dsRNA than for the same sequence of dsDNA [28][29][30][31]. While parallel

• -bonding (Figure 6) [94]. A significant bottleneck for triple helix formation is the requirement for cytosine protonation to form the natural C+•G–C triplet. Because of the low pKa of cytosine (≈4.5), formation of the C+•G–C triplet is unfavorable at physiological pH, which severely destabilizes the

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• reaction between 54 and 55 was performed in anhydrous methanol under an argon atmosphere to construct 56. The study on the in vitro drug release showed enhanced drug release at an acidic pH value in comparison to a neutral pH value. Importantly, the amount of DOX required for MCF-7 cells was decreased

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• solid; mp 196–197 °C; 1H NMR (CDCl3, 600 MHz) δ 7.56–7.62 (m, 5H, Ph), 7.79, 7.84 (2 t, J = 7.5 Hz, 1H each, C6H4), 8.17, 8.30 (2 d, J = 7.7 Hz, 1H each, C6H4); 13C NMR (CDCl3, 151 MHz) δ 119.9 (q, 1JC,F = 270.4 Hz, CF3), 120.8 (i-C), 125.7 (2CH), 127.3, 127.5 (CH each), 129.0 (2CH), 130.3 (CH), 132.9

Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings

• Ivan P. Mosiagin,
• Olesya A. Tomashenko,
• Dar’ya V. Spiridonova,
• Mikhail S. Novikov,
• Sergey P. Tunik and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105

• substituents (H, Me, MeO, Ph, 4-MeOC6H4) at the pyridine moiety of 16, with the exception of electron-withdrawing groups (CN, Bz). The reaction of 1H-pyrido[2,1-a]pyrrolo[3,2-c]isoquinolin-4-ium bromides 17a,c–h with KOH at room temperature gave quantitatively bases 18a–h. The structure of 17a was confirmed by

• XRD-analysis (Figure 3). It was found that both salt 17a and base 18a can be isomerized into isomer 19 under heating in the presence of AlCl3 via migration of the 3-Ph-group into the position 2 (Scheme 6). Compounds 18a, 19 can be quantitatively N-alkylated by MeI at room temperature and by BnBr at 40

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• assay in 96-well microtiter plates with YM6.3 media (10 g/L malt extract, 4 g/L glucose, 4 g/L yeast extract, pH 6.3) for filamentous fungi and yeasts, and with BD DifcoTM Mueller Hinton Broth for bacteria. The antimicrobial assays were performed as previously described [13]. Cytotoxicity assay The

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• acetate, pH 4.5) using a kitchen blender. The obtained homogeneous extract was filtered through a cheesecloth to remove solid material. Then the homogenate was mixed with a half-volume of chloroform and centrifuged at 15,000 rpm for 15 min using a JA-14 rotor (Beckman Coulter, USA). After that, the

• sodium acetate, 8 mM magnesium acetate, pH 4.5). The solution was ultracentrifuged through a sucrose gradient at 30,000 rpm for 2 hours, at 4 °C. The virus was recovered from the blue band, and the sucrose was removed by ultracentrifugation. The pellets were resuspended in virus suspension buffer (50 mM

• sodium acetate, 8 mM magnesium acetate, pH 4.5). All the procedure was done at 4 °C. The virus’s concentration and purity were determined by UV–vis spectrophotometry, and the virus aliquots were kept at −80 °C. The protein purification was performed according to a previously described protocol [40

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• geometric isomer was subjected to the reaction with isopropylmagnesium chloride [23][24][25][26]. Alkyne 4e, having a 13C-labeled carbon atom at the 2-position of the propy-1-ynyl group, was exclusively formed in both cases (Scheme 6b and c) [27]. These results demonstrated that the C–Ph bond was cleaved

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• overall interpretation is that the condition variety did not drastically affect ESR results of each sample. HGCM-PEGMEMA has the highest ESR in every condition that is in good agreement with the nonionic and highly flexible structure of PEG that can resist electrolytes and pH stimuli. On the other hand

• , PAAM and PAA depicted significantly decreased ESR results, which are confirming the subsequent network formation by occupying the pores. The gap between the ESR results in each network could be considered as their patching efficiency. HGCM-PAAM performed a slight decrease from low pH to high pH value

• due to amine groups' protonation on the polymer backbone via electrostatic attraction, and it responded to monovalent electrolyte with a higher ESR. With the increased pH, HGCM-PAA eventuated with enhanced ESR results arising from the dissociation of carboxylic acid groups. Swelling in saltwater

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