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

• -containing mixture of diastereomeric alicyclic derivatives 59. The tetrahydropyrimidin-4(1H)-one-mercuri trifluoroacetate derivative 59 on successive treatment with NaBr and LiBH4 gives a mixture of tetrahydropyrimidin-4(1H)-one derivatives 60 in the diastereomeric ratio of 63:37 after separation by column

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

• fractions. The MeOH fraction was subjected to separation on a silica gel column (CHCl3/MeOH/H2O 6:1:0.1 → 1:1:0.1) to afford five fractions (BM1–BM5). Fraction BM3 (2.5 g) was fractionated over an RP-C18 silica gel column, eluting with gradient solvent system (25 → 100% aq. MeOH) to give nine subfractions

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• chromatography separation is not usually required. This outcome indicated that the transformation could be applicable for larger-scale syntheses of 3-monohalooxindoles products. In addition, the structure of all products 3 and 4 was unambiguously assigned by 1H and 13C NMR spectroscopy and HRMS. Especially the

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

• vigorously for one and a half hour until satisfactory phase separation was achieved. The aqueous layer was separated and subsequently extracted three times with ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulfate and evaporated. The residue was purified by flash

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

• thermoresponsive behavior of polymers is governed by oriented polymer–polymer interactions, such as hydrogen bonding or electrostatic interactions. As a function of temperature, these attractive interactions are formed and contribute to phase separation (T < UCST) or are increasingly destabilized and allow

• separation with an LCST or UCST and its dependence on brush parameters, such as local concentration, and thus on its influenceability. It has often been shown experimentally that the most pronounced conformational response of polymer brushes is achieved at moderate grafting densities [125]. Furthermore, the

• the chains on a surface and the intermolecular interaction that occurs, vertical phase separation is suppressed in systems such as polystyrene in cyclohexane, in contrast to free dissolved chains [128]. However, at vanishingly small concentrations, classical brushes always exhibit a behavior

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

• (7g, Scheme 11). However, dimetathesized product (±)-18c was not formed, and isolation of monometathesized products (±)-18a and (±)-18b (or a mixture thereof) in pure form failed despite repeated attempts of chromatographic separation. Finally, isoxazoline (±)-5 was subjected to CM with 4

• attempts of chromatographic separation. Finally, CM reactions between isoxazoline (±)-6 and 4-fluorostyrene (7h) were studied (Scheme 18 and Table 16). HG-2 catalyst provided monocoupled (±)-25a and dicoupled (±)-25c in a comparable amount. With G-2 catalyst, both products were formed in higher yield. G-3

• regioselectivity in all successful CM reactions. The ratio of monometathesized products in CM reactions of (±)-4 and (±)-5 also depended on the catalyst. Generally, HG-2 catalyst provided the highest regioselectivity. Unfortunately, separation of regioisomeric monometathesized compounds proved to be impossible in

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

• from the N-2 position to the N-1 atom by the indazole C-3 substituent (vide infra). While the corresponding N-1 and N-2 regioisomers arising from the N-alkylation of C-3 substituted indazoles 12–24 were generally amenable to separation using wet flash column chromatography, the corresponding N-1- and N

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

• to create an epimeric mixture of the dinucleotide phosphoramidate-linked derivatives with subsequent separation of the two stereoisomers. These were then incorporated into the desired ONs after O3’-desilylation and phosphitylation of the dimers [107]. The authors found that for each of the sequences

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• treated with (−)-menthoxyacetyl chloride, followed by separation of the diastereomers. The chiral auxiliary was then removed with LiOH and the resulting sultams 27-5 as single enantiomers were fluorinated with 15% F2/He in the presence of KF to produce optically pure N-fluorosultam reagents (R)- and (S

• of 28-2, which was accompanied by 45% of unreacted 28-1. Interestingly, pure (R)-isomer 28-1 was obtained in 20% yield from the unreacted 28-1. The diastereomer separation of 28-2 was achieved by column chromatography to separate the (R)- and (S)-isomers of 28-2 in 21 and 31% yields, respectively

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

• mixture was incubated for 1 h at 60 °C. For separation of polysaccharides, 180 µL 5 M NaCl and 80 µL 10% CTAB were added and the mixture incubated further for 10 min at 65 °C. To extract nucleic acids by phase separation, 860 µL chloroform/isoamyl alcohol (24:1) was added and incubated on ice for 30 min

• detector (interface temp, 270 °C; quadrupole temp, 150 °C; source temp, 230 °C; electron energy, 70 eV). Chromatographic separation was achieved with an initial oven temperature of 45 °C held for 2 min, which was then increased to 180 °C with a gradient of 6 °C min−1, and then further increased to 300 °C

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• determined by 1H NMR spectroscopy. Chromatographic separation was carried out on silica gel 60H (200–300 mesh) manufactured by Qingdao Haiyang Chemical Group Co. (China). High-resolution mass spectrometry (HRMS) was measured on a Thermo-DFS mass spectrometer. NMR spectra were recorded on a JEOL 600 NMR

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• % and exclusively β-selective [11]. Isomeric separation of this complex mixture was not completed at this stage and the material was next deprotected using hydrogenolysis to remove the benzyl groups. This furnished 20 in excellent yield (96%) as a 3:1 α/β mixture (δ 100.5 ppm [1JC1-H1 = 172 Hz, for the

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• or minimize the formation of diol 11 by performing the reduction step at temperatures lower than 15 °C but this significantly reduced the yield of the desired product, even with longer reaction times. Therefore, we had to be satisfied with separation of desired product 8 from unwanted 9 after the

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

• strands of the duplex with separation of one regular base pair from each other [54]. 1,5-Furanosyl double-headed nucleosides In this category, the nucleosides contain the first natural nucleobase at the C-1′ position and the second natural nucleobase/aromatic moiety/heterocyclic ring attached at the C-5

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

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

• scale-up equating to prolonged run times. As a result, alternative support formats have been investigated. In this context there has been a growing interest in the use of functionalised hollow fibres including their application as membranes for gas separation [110] (e.g., CO2 absorption [111]) as they

• mixture is biphasic, and a preliminary separation is carried out before entering the reactor coil. After discontinuous purification procedures, the product 82 was yielded in 98% purity (72% yield). The second step, instead, is an acid-catalysed cyclisation which employs the same tubular reactor at lower

• system with the steam being recycled back through the reactor. After phase separation, the obtained mixture was enriched to 85% of 83 (equating to a 73% isolated yield). Once the reaction conditions were optimised, the apparatus can merge with other flow systems to develop a parallel continuous multistep

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• , thus leading to an enhanced optical absorption, improved electron-hole separation and easy dispersion in polar solvents [32]. CN-K, which can be easily prepared by the direct KCl-induced structure remodeling of bulk g-C3N4 [33][34][35][36], showed great potentials for future industrial applications

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• , the same porphyrin overlap seen in Figure 2A is apparent (Figure 11A) with a separation of 3.359(2) Å between the porphyrin layers. This is coupled with a short contact between the bromine atoms and the meta-hydrogen of the phenyl ring tethering porphyrin molecules to the one above it (Figure 11B

• above with a separation of 3.255(5) Å (Supporting Information File 1, Figure S18). Interestingly, this structure features both arrangements previously seen with a close packing observed between both pyrrole (Supporting Information File 1, Figure S19A) and hexyl (Supporting Information File 1, Figure

• Information File 1, Figure S30) establish the packing pattern seen in Supporting Information File 1, Figure S23. As with compound 1, the stacking between the porphyrin layers is organized with the bromine atoms overlapping with each other at a separation of 3.306(3) Å among the porphyrin macrocycles. In

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• and 12 under these conditions produced the expected thioglycosides 18 and 19, respectively. Difluorinated derivative 13 decomposed on reaction with the PhSTMS/ZnI2 system. The separation of the anomers of products 14–19 was attempted because of the risk of thiophenyl migration in the subsequent C6

• deoxyfluorination, which would likely occur with the β-anomers of 14–19 [41]. The complete separation of the α-anomer by conventional silica gel column chromatography was possible for thioglycosides 14, 16, 17, and 19, while the products 15 and 18 were obtainable as enriched α-anomers (α/β ≥ 3.3:1). Cleavage of the

Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• reaction was cooled to room temperature, and the product was isolated, either by adding 4 mL of water, which dissolves the DES, and extracting the nitroalkane with AcOEt, or by direct separation of the organic residue from the eutectic mixture (see below for recycling experiments and Supporting Information

• extraction of the product and its separation from the eutectic mixture. However, when the recycling protocol was studied, in order to reuse the DES, at the end of the reaction, water was not added, and the product was extracted by simply adding ethyl acetate and separating the upper, organic phase. The DES

• the use of any organic solvent, the reduction of 3h was performed with a 1 M substrate concentration and afforded, in DES B, nitroalkane 4h in 74% yield, which was isolated as pure compound by a simple liquid–liquid biphase separation from the eutectic mixture (see details and pictures in Supporting

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• using a Histopaque®-1077 (Millipore Sigma, MA) density separation to collect the buffy coat. Thereafter, the buffy coat was subject to a Percoll® (Cytiva, MA) density separation to enrich for the monocyte population in the buffy coat. Monocytes were counted and stored in Cyrostor-C5 (BioLife Solutions

Synthesis of bis(aryloxy)fluoromethanes using a heterodihalocarbene strategy

• Carl Recsei and
• Yaniv Barda

Beilstein J. Org. Chem. 2021, 17, 813–818, doi:10.3762/bjoc.17.70

• undesired isomer were produced, recovery of unreacted 6 was simple and the quantity of 8 (<5%) was reduced compared to all previous attempts. Chromatographic separation permitted the removal of 8 and the isolation of a pure sample of compound 4. Synthesis of compound 1 Having produced the key intermediate 4

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• scaling up the preparation of two pincer-type thioamides, we have successfully developed a convenient process with ethylene glycol to replace ethanol during the workup, including a traditional phase separation, extraction, and recrystallization. The newly developed chromatography-free procedure did not

• separation by careful column chromatography is necessary because of both the similar polarity and the stoichiometric amount of the formed compound A. With regard to this, the use of LR was always limited to small-scale preparations [6][8]. Other than the exploration of potential surrogates of LR for the

• , we herein reported an efficient work-up procedure of applying LR by utilizing ethylene glycol to decompose the compound A (Figure 2). With a combination of some usual operations, such as, phase separation, extraction and crystallization, the desired thioamide products were efficiently obtained in

DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies

• Yongdong Su,
• Maitsetseg Bayarjargal,
• Tracy K. Hale and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2021, 17, 749–761, doi:10.3762/bjoc.17.65

• creates a chiral center at the phosphorus atom resulting in a mixture of 2n diastereomers, where n is the number of modified phosphate groups. The reverse-phase (RP) HPLC purification occasionally results in the separation of individual diastereomers (usually for ONs with a single modification), which

• , the separation of ONs with varying numbers of modifications was not ideal as there were only marginal changes in the retention time in RP-HPLC. Therefore, ion-exchange (IE) HPLC was used for purifying these ONs. The substitution of each phosphate with N+ modification, resulted in a shorter retention

β-Lactamase inhibition profile of new amidine-substituted diazabicyclooctanes

• Zafar Iqbal,
• Lijuan Zhai,
• Yuanyu Gao,
• Dong Tang,
• Xueqin Ma,
• Jinbo Ji,
• Jian Sun,
• Jingwen Ji,
• Yuanbai Liu,
• Rui Jiang,
• Yangxiu Mu,
• Lili He,
• Haikang Yang and
• Zhixiang Yang

Beilstein J. Org. Chem. 2021, 17, 711–718, doi:10.3762/bjoc.17.60

• CH2Cl2. The low yield of this reaction was due to the formation of two isomeric products as revealed by TLC and subsequent analysis by analytical LC–MS. The NMR spectra of both isomers, after chromatographic separation, showed different chemical shifts for the protons at C2 position of the DBO ring