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

• -phenylporphyrin (4) Pre-dried 5,15-bis(4-methylphenyl)porphyrin, (100 mg, 0.2 mmol, 1 equiv) was dissolved in 37 mL dry THF. A solution of 0.7 mL PhLi (1.8 M in dibutyl ether, 1.28 mmol, 6.4 equiv) was added at 0 °C under stirring, resulting in a color change from purple to green/brown. Following the complete

• addition, the cold bath was removed and stirring was continued for an additional 45 min. Subsequently, pre-dried DDQ (291 mg, 1.28 mmol, 6.4 equiv) was added, resulting in a color change from green/brown to dark purple/brown. Stirring was continued for 1 h, and the solvent was removed under reduced

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

• Chiara Faverio Monica Fiorenza Boselli Patricia Camarero Gonzalez Alessandra Puglisi Maurizio Benaglia Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi, 19, I-20133, Milano, Italy 10.3762/bjoc.17.83 Abstract Deep eutectic solvents (DESs) have gained attention as green and

• whole research community concerned with the concept of a circular economy [3]. In this context, deep eutectic solvents (DESs) have attracted an increasing attention as green, safe, economically and environmentally sustainable alternative to the traditional organic solvents [4]. They are combinations of

• materials that can be used to form eutectic mixtures offers an incredibly high variety of combinations to generate new, safe and biodegradable DESs [5]. Another fundamental principle of green chemistry is the atom economy concept. In this context, ammonia borane (AB) is receiving increasing attention as

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• ; with 5% v/v DMSO) in the absence and presence of 5a (A), and 5d (B) at LDR = 0 (black), 0.05 (orange), 0.2 (blue), 0.5 (green), 1.0 (red). The arrows indicate the changes of CD and LD bands with increasing LDR. Synthesis of 10-O-arylated berberine derivatives 5a–e. Cu2+-catalyzed demethylation of

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• . reported a ″green″ glycosylation procedure by employing supercritical CO2 (scCO2) as a weakly Lewis acidic reaction medium [37]. The method was successfully applied for the synthesis of O-glycosides from disarmed glycosyl chlorides and bromides in the absence of additional promoter. Herein we disclose a

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

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• majority of the atoms of the starting materials. The ability of forming multiple bonds in one-pot via a multicomponent reaction provides a novel and sustainable method in drug discovery [4]. In the recent years, these reactions have emerged as a promising strategy following green chemistry principles such

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

• in line with the theme of green chemistry. This review discusses the synthetic reactions concerned with EDA complexes as well as the mechanisms that have been shown over the past five years. Keywords: EDA complex; electron acceptor; electron donor; radical; visible light; Review Introduction

• majority cases. Moreover, in line with the theme of green chemistry, light is the sole external energy source in EDA complex pathways. Except for the pioneering research on EDA complexes in the 20th century, there was not much progress in the follow-up. Until the past few years, EDA-complex photochemistry

• in good to excellent yield. The protocol conforms to the characteristics of green and environmental conservation, having a reaction time of only 1 hour, achieving the purpose of saving energy. In 2019, Liang and colleagues [24] reported a method for preparing perfluoroalkyl-s-triazine via visible

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• , 164 mg, 1.05 mmol) was added as a solid in a single portion. Ferrocenium hexafluorophosphate (4, 397 mg, 1.2 mmol) was added in small portions with vigorous stirring until a dark blue-green color of the reaction mixture persisted for 20 min. The reaction mixture was quenched by saturated NH4Cl

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• led to a better yield at 140 °C than in the acetonitrile/water mixture. Finally, we tested NMP as a green solvent that is also one of the safest choices for performing high-temperature MW-assisted syntheses (high boiling point, nonvolatile). Even though it brings difficulties towards product isolation

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

• this underdevelopment is that chemolysis of plastics is still challenging due to multiple critical factors: i) the achievement of selective depolymerisation is only possible by carefully controlled reaction conditions, ii) the related processes must be “green” and economically viable and, iii) tailored

• application in many fields [234][235], though they cannot be considered inherently “green” [236]. In a recent work, the DES combination zinc acetate and 1,3-dimethylurea (1:4) showed the highest catalytic activity among a series of transition metal acetates (Zn, Mn, Co, Ni, Cu), affording BHET with 82% yield

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

• solvent (DMF, MeCN, ethyl acetate, DMSO, solvent free) on the activity and selectivity of the nanocatalysts has been noted [27][41][42][43][44]. Furthermore, all the reported methodologies use either molecular oxygen together with an aldehyde as a co-reductant, or only a “green” peroxide (H2O2, TBHP) as

• (3 mL) was added and the reaction mixture was stirred at room temperature until it turned dark green (5–10 min), indicating the formation of the corresponding lithium arenide. Anhydrous cobalt(II) chloride was then added (130 mg, 1.0 mmol) and the resulting suspension was stirred until it turned

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• air/water interface (25 °C). Variation of surface pressure π as a function of time for 1 (blue), 2 (magenta), 3 (green), and 4 (black). Adsorption of perfluoroalkylated lipopeptides 1–3 and hydrocarbon analog 4 on DPPC monolayers spread at the air/water interface a) in the liquid expanded (LE) and b

• ) in the liquid condensed (LC) phases (25 °C). Variation of the surface pressure π as a function of time for a DPPC monolayer (red), and after injection of the lipopeptides in the aqueous sub-phase of a DPPC monolayer for F-lipopeptides: 1 (blue), 2 (magenta), 3 (green), and hydrocarbon analog 4 (black

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• intrinsically disordered proteins remains unclear. 6 Fluoroprolines in crystal structures of proteins Several high-resolution crystal structures have been reported for proteins containing fluoroprolines. In a study of enhanced green fluorescent protein from Aquorea victoria, fluoroprolines were incorporated at

• faster amide rotation kinetics, has been reported for fluoroproline containing cysteine-rich minicollagen domains [141], green fluorescent protein [117][142], ubiquitin [133], β2-microglobulin [136], thioredoxin A [119][143] and red fluorescent protein [137]. In addition, the effects of the fluoroproline

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• ) and MESP contour map (right) for the molecule of 8a. The calculated plots in n-hexane of a) HOMO, b) LUMO, c) electron density difference between the S1 and S0 states, and d) the S0→S1 CT. Green (blue) regions (for c and d) indicate an increase (decrease) in the electron density upon the electronic

• transition. The red arrow shows the charge transfer. The calculated plots in water of a) HOMO, b) LUMO, c) electron density difference between the S1 and S0 states, and d) the S0→S1 CT. Green (blue) regions (for c and d) indicate an increase (decrease) in the electron density upon electronic transition. The

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

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• ether from 0 to 50%) afforded the pure ferulates 1a, 1b, 3–9, and 12. 5-Bromo-4-chloro-3-indolyl 5-O-trans-feruloyl-α-ʟ-arabinofuranoside (1a, 107 mg, 0.19 mmol, 73%). Green-yellow foam. The NMR data (CD3OD) were consistent with those previously reported [15]. 4-Nitrophenyl 5-O-trans-feruloyl-α-ʟ

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

A sustainable strategy for the straightforward preparation of 2H-azirines and highly functionalized NH-aziridines from vinyl azides using a single solvent flow-batch approach

• Michael Andresini,
• Leonardo Degannaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20

• and potentially automatable method for the synthesis of interesting strained compounds. Keywords: aziridines; 2H-azirines; flow chemistry; green chemistry; organolithium compounds; Introduction Since their conception in the early 1990s, Green Chemistry Principles (GCP) have been applied with

• to access aziridines with great structural variability [21]. The reaction of azirines with Grignard and organolithium reagents has been poorly investigated, and only without using green and renewable solvents [22][23]. In turn, 2H-azirines can be smoothly obtained through intramolecular cyclization

• cyclisation of 1-(1-azidovinyl)-4-methylbenzene (1a) in refluxing 2-MeTHF and cyclopentyl methyl ether (CPME) as green solvent candidates, and compared the results with the reaction conducted in toluene (Table 1). The reaction proceeded rapidly in CPME, while the use of 2-MeTHF resulted in longer reaction

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• the F4Az-based assemblies did not show fluorescence behaviour, the following discussion focuses on the assemblies NO2-C9∙∙∙F4St as representative example. The fluorescence of NO2-C9 appears yellow-green, while F4St is non-fluorescent. Upon formation of the halogen-bonded liquid crystal, green

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• -complementary [14] binding units (BU, blue) and a connecting linker unit (LU, green) to connect the BUs. In this case, the BUs are ureidopyrimidone units, which dimerize due to a fourfold hydrogen bond, thus allowing for strong supramolecular interactions [15]. Due to the flexibility of the LUs, the BUs can

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• , green, and was carried out in a facile operative environment without using any hazardous transition metal catalysts or any other coupling reagents. Different aromatic aldehydes and azaarenes were monitored, and the yields of the resulting products were moderate to excellent. We accomplished several

• azaarene derivatives under neat conditions through a highly atom-economical pathway. To evaluate the preparative potential of this process, gram-scale reactions were performed up to a 10 g scale. Keywords: aldehydes; azaarenes; benzylic addition; green chemistry; solvent-free conditions; Introduction

• reevaluated. Therefore, alternatives with environmentally benign reagents are much in focus. Correspondingly, considering the exemplar shift from conventional synthetic methodologies towards green chemistry, there have been some alternatives or replacements of toxic catalysts and hazardous solvents in

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

• temperatures, which requires the use of air-free techniques in the laboratory. Et3B in the pure form has limited commercial availability and is known to spontaneously react with oxygen to produce a green flame [36]. To avoid the pyrophoric properties of triethylborane, this reagent is mostly sold in low

Semiautomated glycoproteomics data analysis workflow for maximized glycopeptide identification and reliable quantification

• Steffen Lippold,
• Arnoud H. de Ru,
• Jan Nouta,
• Peter A. van Veelen,
• Magnus Palmblad,
• Manfred Wuhrer and
• Noortje de Haan

Beilstein J. Org. Chem. 2020, 16, 3038–3051, doi:10.3762/bjoc.16.253

• glycopeptide clusters detected by GlycopeptideGraphMS. Representative GlycopeptideGraphMS output for peptides of interest. Assigned compositions were identified using MS/MS data via Byonic (green) or manual assignment (blue) or by MS1 only (red, GlycopeptideGraphMS with additional accurate-mass and isotopic

• pattern check of the raw data). The assignment of the compositions is based on information from all replicates. Lines between compositions indicate the mass difference for Hex (yellow), HexNAc (blue), HexHexNAc (green), Fuc (red), and NeuAc (purple). * Indicates potential deconvolution errors and

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• practical application, due to the use of labile and expensive reagents. Moreover, the elimination of metal trace residues and wastes is of some concern particularly for products destined to pharmaceutical applications as it is imperative operating under ‘green’ conditions. As for the last issue, there is

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• -acetylphenylalaninate. Design of chiral calix[4]arene-based receptors for anions. X-ray structure of 4a: (a) Top view into the cavity. (b) Side view of the same cavity. X-ray structure of 7a: (a) Hydrogen bonding interactions (black) in a dimeric motif, chalcogen interactions are shown in green. (b) π–π interactions in

• the dimeric motif. X-ray structure of 7d, showing hydrogen bonds between the ureido units (green) and hydrogen bonding of acetone molecules (black). One alkyl group in each calixarene was removed for better clarity. 1H NMR titration of 7c with N-acetyl-ᴅ-phenylalaninate and N-acetyl-ʟ-phenylalaninate