Structure and thermal stability of phosphorus-iodonium ylids

• Andrew Greener,
• Stephen P. Argent,
• Coby J. Clarke and
• Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

• functionalities they can transfer. In this study, a fundamental understanding of the thermal stability of phosphorus-iodonium ylids is obtained through X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Insights into the structural factors affecting thermal stability

• and potential decomposition pathways will enable the future design and development of new reagents. Keywords: hypervalent iodine; reagent development; structural analysis; thermal stability; thermogravimetric analysis; Introduction Hypervalent iodine(III) reagents have experienced a renaissance in

• vital to gain a fundamental understanding of the structural factors affecting their stability and reactivity. Previous reports have suggested a link between structural factors and thermal stability of hypervalent iodine compounds [10][11][12][13][14][15][16]. Iodine(III) compounds are generally trigonal

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• capability to function as radical initiators. The use of diaryliodonium salts as efficient electrophilic arylating reagents in a wide range of organic transformations is due to their unique features such as solid-state nature, excellent stability, and the presence of a robust leaving group [39][40][41][42

• diaryliodonium salts. Recent advancements in this field have focused on the development of practically simple and scalable methods for the arylation of oxygen using diaryliodonium salts. By modifying the counter anions attached to the iodonium ion, the stability and reactivity of new symmetrical and

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• intermediate C which underwent extrusion of iodine and dipropyl disulfide to give intermediate D. Subsequent reaction with acetic anhydride, pyridine and KHF2 resulted in the replacement of the TMS by acetyl groups which was important for practical reasons (stability during chromatography). The reaction of 13

• -β-41a (55%) and E-β-41a (41%) are in accordance with the relative thermodynamic stability of the two geometric isomers. According to DFT calculations, the Z-isomer is slightly energetically favored by 14.88 kJ/mol. The configurations were determined by comparison of chemical shifts of our products

• represents a π-donor. Although nitrogen, as present in indirubins 17, is an even better donor than oxygen, the stability of the intramolecular hydrogen bond overrules this effect. Sulfur and selenium are very weak π-donors. It was not studied so far whether the E/Z ratio of indirubin derivatives can be

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• stability than boronic acids and other employed esters as the four methyl groups protect the boron center from attack of water [44][45], preventing protodeboronation from the hydrolysis route. However, protodeboronation can be complex when it comes to pKa considerations, for example, 3,5

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• reactants. Therefore, based on the previous studies on the oxidative 3-component Ugi–Joullié reaction [22][23][24] and our precedent experience [25][26][27], we speculated that cyclic imines could be good substrates for our reaction, thanks to their higher rigidity and stability. As depicted in Scheme 2b

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• differences in energy between the stationary points, the better the exploration of the catalytic space. To determine the set of scaffolds to be used for volcano plot analysis, the CO2–FLP adduct of each of the fourteen scaffolds was optimised (Figure 3). Based on the stability of the optimised adducts

• kcal·mol−1. Remarkably, among the most efficient catalysts within this group of FLPs those with a nitrogen LB stand out. This phenomenon could be attributed to the exceptional stability of the covalent adduct formed between phosphorus-based FLPs and CO2. The second group comprises compounds that undergo

Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study

• Stiliyana Pereva,
• Stefan Dobrev,
• Tsveta Sarafska,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221

• light on the mechanism of the γ-CD hydration and to address some unanswered questions: (i) what are the preferable locations for water molecules in the macrocyclic cavity (“hot spots”); (ii) what are the major factors contributing to the stability of the water cluster in the CD interior; (iii) what type

• of interactions (i.e., water–water and/or water–CD walls) contribute to the stability of the water assemble; (iv) how does the mechanism of the γ-CD hydration compare with those of its α-CD and β-CD counterparts. Keywords: cyclodextrin; DFT calculation; DSC/TG; hydration; thermodynamic

• hydrogen bonding, although generally not dominant, can influence the complex formation as well [5]. Cyclodextrins form inclusion complexes with polar and non-polar substances of various aggregate states. This incredible versatility, combined with the enhanced stability against oxidation, as well as

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• that the hierarchal molecular self-assembly of these materials into larger structures directly influences behaviours such as performance and stability. It is therefore imperative that these materials are characterised effectively over multiple length scales. Two effective methods of achieving this are

• attached to the molecules themselves or is interacting with them. Introducing fluorescent dyes to self-assembling systems affects their chemical and mechanical stability as the hydrophobic features can destabilise the self-assembled network [18]. This reliance on fluorescence labels or dyes leading to a

• crystallise and disrupt the network, or change the stability and solubility of any charged structures present. All of these issues could result in statistics which are not representative of the structures in situ [31]. To overcome this, cryogenic techniques are widely used to allow the investigation of a

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• fragments and hydrogen bonds leads to the alteration in chemical behavior. Based on the aforementioned stability of tetronic acids 4 toward action of MeOH we supposed that various derivatives at the hydroxyethylidene group can be synthesized. For example, interaction of compound 4a with hydrazine in

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• , indicating that the activated gold complex is the catalytically active species. Furthermore, stability measurements (1H and 19F NMR) of 1:1 mixtures of the gold complex and the XB donors were performed in order to investigate the stability of the cationic iodonium structures towards the gold complex [28

• ]. For all catalyst systems, decomposition of the −BArF24 anion was observed via 1H and 19F NMR spectroscopy, which is known to happen in the presence of activated gold complexes [29]. The stability of the DAI cations was checked with 1H NMR: the characteristic doublets belonging to the respective

• iodonium structures 1+, 2+, 3+, and 7+ were found to be constant (see Supporting Information File 1). The signals of the iodoxinium cation 4+ were overlapping with signals of the anion. However, the stability of 4+ (as well as of 2+) could be confirmed by 19F NMR measurements: no decomposition of the

Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system

• Yuri A. Sidunets,
• Valeriya G. Melekhina and
• Leonid L. Fershtat

Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200

• recorded for compound 1f – 36.9%. Therefore, the synthesized triazinones 1 exhibit a wide range of NO-releasing properties and could be considered as potential drug candidates. Additionally, thermal stability of the obtained triazinones 1 and 7 was evaluated by differential scanning calorimetry. The

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• (IEDDA), and recently, azomethine imine (AMIs)–isonitrile ligation [37][55][56][57][58][59][60]. The kinetics, chemoselectivity, stability, and steric demand of the bioorthogonal tag attached on the probe are decisive factors during the selection procedure [61][62]. The most commonly used strategy is

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• stability of thioester groups in aqueous environments, we also decided to apply conditions conducive to hydrophobic amplification [37], which unfortunately also did not yield the intended effect. Another approach is to generate and stabilize the active nucleophile form as an anion thus increasing its

• guanidine motif in AA-3 compared to simple AA-1. Alterations in the thiol structure within thiomalonates significantly impact their stability and reactivity, thereby influencing both reaction efficiency and stereochemical outcome, as demonstrated in the case of catalysis employing bifunctional hydrogen bond

• for phenyl bis-thiomalonate 3. The reaction in toluene required 24 hours to yield an enantiomerically enriched product (92% ee) with a 69% yield. However, achieving such a degree of over-reaction was associated with prolonged reaction times, which may affect the stability of both the substrate and its

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• with the stability of the relevant iminoiodinane reagent, with higher yields attributed to more electron-rich sulfonamide substitution such as 2a. Relatively electron-deficient iminoiodinanes are less efficient but are also more prone to decomposition (see Supporting Information File 1, Figure S2 for

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

Deuterated reagents in multicomponent reactions to afford deuterium-labeled products

• Kevin Schofield,
• Shayna Maddern,
• Yueteng Zhang,
• Grace E. Mastin,
• Rachel Knight,
• Wei Wang,
• James Galligan and
• Christopher Hulme

Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195

• analyses of microsomal stability confirm prolongation of t1/2 of the new deuterated analogs. We also report the first preparation of [D2]-isonitriles from [D3]-formamides via a modified Leuckart–Wallach reaction and their use in an MCR to afford products with [D2]-benzylic positions and likely

• significantly enhanced metabolic stability, a key parameter for property-based design efforts. Keywords: deuterated aldehydes; deuterated formamides; deuterated isocyanides; DHPs; kinetic isotope effect; Leuckart–Wallach; microsomal stability; multicomponent reactions; Introduction Multicomponent reactions

• [D3]-formamide. The ability to deuterate at benzylic positions is particularly relevant as benzylic C–H bonds are common in biologically relevant chemotypes and moreover appear in approximately 25% of the top selling 200 pharmaceuticals [23]. Benzyl cation stability is a driver of metabolism at these

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• . Previously, we reported aromatic hydrocarbon radicals with 9-anthryl (Ant) units at the spin-center carbon, exhibiting high stability (Figure 1a) [16][17][18][19][20][21]. Although bulky phenyl substitutions at the spin-center carbon can also provide high stability [13][14][15], the introduction of an Ant

• state yields the monomer radical [16][17][18]. Therefore, aromatic hydrocarbon radicals with Ant units possess both stability and reactivity depending on the conditions, giving them high potential for use as reactive catalysts [22][23] and stimuli-responsive sensors [24][25]. To further investigate this

• from the basic skeleton of the highly reactive diphenylmethyl radical [26][27][28]. This spin delocalization is similar to that of the galvinoxyl radical, which shows high stability in air [29]. Thus, the DAntM radical would be a stable radical with a reactive site. Additionally, utilizing the reactive

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• alcohols, polyols, polyions or polymers, has a positive effect on protein stability and the soluble fraction expressed with CFPS [17]. The variable composition of CFPS systems with a high number of ingredients and possible reaction conditions [13] thus opens a large parameter space. In addition, non

• the impact of the polymer itself is greater than that of the increased viscosity. A positive effect on the stability and activity of the model enzyme β-ᴅ-glucuronidase by the addition of carboxymethylcellulose has already been reported [49]. However, the effects and states of molecular crowding in the

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• ), which are readily accessible by the oxidative acetylenic coupling of a 1,2-diethynylbenzene derivative (Figure 1) [18]. The chemical stability of DBAs depends on the electronic character of the substituents. Electron-donating alkyloxy groups are known to enhance the stability of DBAs. On the other hand

• , DBAs substituted with electron-withdrawing groups have been little studied [19], and their chemical stability and physical properties are not well understood. In this paper, a new DBA substituted with ester groups was synthesized, and the double azide addition was comprehensively investigated. Finally

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• of a variety of biologically important anions due to the presence of two pyrrolic NH hydrogen bond donors [38][39][40][41][42][43]. Notably, in the past few decades, the chemistry of DPMs have attested to be imperative in the existing chemical research because of their easy syntheses, good stability

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• immobilization strategies, including covalent bonding and encapsulation, cater to different polymer types. Soluble polymers enhance diffusion, while insoluble ones ensure stability and high loading capacities [42]. Silica is also widely applied due to its ease of functionalisation and thermal stability [43]. The

• 39% ee for a pore size of 11.3 nm [64]. Catalyst supports must meet certain criteria, including being chemically inert, and the supported catalyst should exhibit high stability across various reaction conditions while also being easily recyclable [8][64]. When the solid support is not inert, it can

• reactions in a less protic and less polar solvent. Attaching catalysts to solid supports also offers the potential for enhancing catalyst stability. Boyer and co-workers reported the use of silica nanoparticle-supported eosin Y 21 as a photocatalyst in reversible addition fragmentation chain transfer (RAFT

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• -withdrawing group improves the stability of the product 4 (R = p-O2N-C6H4, E = PhSe) and also because phase separation is caused by the product precipitation from the reaction solution. On the other hand, the addition reaction of (PhTe)2 to isocyanides does not proceed at all [30]. This is because the

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

• field of computational chemistry and biochemistry: 1. AMBER [56]: AMBER (https://ambermd.org/) is the acronym for "Assisted Model Building with Energy Refinement", and it is an open-source software widely employed for molecular modelling and simulation. It is known for its stability, user-friendly

• scoring function based on the AMBER force field to evaluate the stability of the complex. DOCK is particularly useful for GAGs due to its ability to accurately model conformational flexibility and enhance sampling, allowing for more precise predictions of ligand–receptor interactions. 7. ATTRACT [138]: It

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• their synthesis have been extensively reviewed [93]. When hydrazones undergo cyclization with β-ketoesters or ketones, the stability of the enol form of the carbonyl compounds plays a crucial role in the reaction. Recognizing this, a series of multicomponent reactions has been developed to synthesize

• consecutive three-component approach in a polymer analogous fashion with diynes 105, terephthaloyl chloride (106), and hydrazines to synthesize high molecular weight pyrazole-based polymers 107 (Scheme 38) [132]. The materials 107 fluoresce in THF solutions, form thin films, and possess high thermal stability