Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• well known as a potent β-lactamase inhibitor [33][34]. It is produced by the filamentous bacterium Streptomyces clavuligerus, but in low yield. Various clavams 2–5 have been identified (Figure 2B), either through isolation as natural metabolites or obtained by synthetic methods [35][36][37][38][39][40

Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols

• Smaher E. Butt,
• Konrad Kepski,
• Jean-Marc Sotiropoulos and
• Wesley J. Moran

Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209

• many organocatalysts [3][4][5], natural products (e.g., the potent α-glucosidase inhibitor (−)-codonopsinol B) [6][7], and pharmaceutical drug molecules such as saxagliptin and ramipril (Figure 1) [8]. Accordingly, the development of methods to access substituted prolines and pyrrolidines is an

• important area of study as this ring system is prevalent in many useful molecules. Typical literature procedures include multistep derivations of proline itself, e.g., the destruction of the stereocenter and then its reinstallation by an enantioselective conjugate addition [9]. Other methods include the

• enantioselective conjugate addition to α,β-unsaturated pyroglutamic acid derivatives followed by deoxygenation [10], and the enantioselective organocatalytic reaction between 2-acylaminomalonates and α,β-unsaturated aldehydes [11][12]. The development of new synthetic methods using hypervalent iodine reagents has

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• interests, no methods have been described to synthesize both trifluoromethoxylated and phenylselenylated molecules. The introduction of a CF3O moiety into organic molecules remains poorly described in the literature, especially the direct trifluoromethoxylation [44][45][46]. Only few radical

• trifluoromethoxylations of (hetero)aromatics [47][48][49][50][51][52], enol carbonates [53] or silyl enol ethers and allyl silanes [54] have been reported. Most of the methods described have used the trifluoromethoxide anion (CF3O−) [45]. Many sources of the CF3O− anion have been described, but with certain drawbacks

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• sequence from the corresponding chiral 4,4,4-trifluoro-3-hydroxybutyrate at low temperature [27][28][29][30], and 2) t-BuO2Li-mediated transformation of the enoates like 1g at −78 °C [31][32] and, to the best of our knowledge, no report has appeared on the convenient methods applicable to the larger scale

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• serve as guidance for industrial production. Experimental Materials and methods Chemicals O-Methylisouronium sulfate (IO, 95%) was purchased from Shanghai Yien Chemical Technology Co., Ltd; fuming nitric acid (HNO3, 98.0%) was purchased from Sinopharm Chemical Reagent Co., Ltd.; sulfuric acid (H2SO4

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• , compounds 6–9 are products of alkylation of the nitrogen atom of the heterocycle. Thiones 6–9 were obtained in 40–79% yield (Scheme 1,b). The structures of synthesized compounds were confirmed by the spectral methods IR-, 1H NMR, 13C{1H} NMR spectroscopy (Figures S1–S18 in Supporting Information File 1

• fragment favors the pronounced antiradical activity. The use of ABTS radical cation to assess the antioxidant capacity of compounds is one of the widely used methods which is based on the transfer of an electron from the studied molecules to the acceptor [67]. The obtained IC50 values for synthesized

• -thiazolyl (34.0 ± 0.10 μM). Compound 1 was the least effective in this test (81.10 ± 1.86 μM) as in the case of the methods described above. We have previously shown that catechol thioethers can act as anti- or prooxidants on lipid peroxidation processes in vitro depending on a functional group or a

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• %) are nitrogen-containing organic compounds, with many featuring amino groups adjacent to a stereogenic centre. Some reports suggest that 75% of all FDA-approved compounds are alkaloids [2]. The industrial production of amines on a million-ton scale underscores the significance of methods for their

• ][18][19][20][21][22][23], none have focused specifically on organocatalytic approaches, which are particularly important for medicinal chemistry due to their greener credentials. Given the wide range of organocatalytic methods for synthesising homoallylic amines developed in the past decade, it is

• enantioselectivities (30–65% ee) and low to moderate yields (49–81%). However, despite the modest enantioselectivity, the proposed approach presents an appealing strategy towards chiral homoallylic amine scaffolds 150 that are difficult to achieve using other methods. Conclusion Summarising all the analysed approaches

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

• attempted, in which the coupling of the probe–peptide conjugate with a suitable reporter tag may help to improve the detectability in an excess of probe-unmodified peptides [65][81][82]. The speed of acquisition of mass spectra of the current LC–MS/MS methods does not ultimately cover all unmodified and

• proteome and enrichment-based methods. There are several chemical proteomics linkers reported that improve ionization of the probe–peptide conjugates or release a reporter ion during fragmentation or both (Figure 7). The reporter ion is important as it may serve two purposes. First, it facilitates the

• fragmentation performance, the combination of HCD and ETD can be used in a single MS measurement. In such methods ETD is only triggered by probe-specific diagnostic ions released by the faster HCD fragmentation with the aim to fragment the same parent ion again with ETD to obtain a better fragmentation spectrum

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

• ][5]. The transient impact of kinetic energy, channeled into the reaction, facilitates overcoming the constraints inherent in equilibrium models. Thus, employing limited substrates could potentially yield diverse products through a simple alteration of conditions, compared to solvent-based methods [6

• conditions are provided by mechanochemistry methods in ball mills. The reaction performed in a mixer mill over 1 hour only led to 13% of sulfa-Michael adduct (see Supporting Information File 1) beside the expected enantioenriched product (69%, 78% ee). We assumed the energy impact generated in the mixer mill

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

• energies of relevant species either via force field or quantum chemical methods to assess the properties of a reaction such as activation energies or selectivity. Irrespective of the degree of automation, in silico calculations are often less time-sensitive than wet-lab experiments and can be used to

• reduce the number of required experiments. As such, these methods contribute to the acceleration of catalyst discovery, for example through high-throughput virtual screening. Predating these computational techniques is the desire to understand and explain experimental outcomes in organic chemistry with

• threshold 60%). Thus, the authors recommend that for developing a new reaction, their metric can be used to decide which catalyst should be tested first based on the expected success. This generality-based guiding principle of experimental design showcases a further possibility for data-driven methods to

gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• Organofluorine compounds have attracted great attention in various fields, such as organic materials and pharmaceuticals [1][2][3], because fluorinated compounds sometimes show specific properties [4]. So far, several methods have been developed for the synthesis of fluorinated compounds. Using nucleophilic

• fluorobenziodoxole, are also utilized as F+ equivalents to introduce fluorine atoms into organic molecules. In addition, various trifluoromethylation reagents have been developed so far [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Transition-metal-catalyzed fluorination and trifluoromethylation methods have

• blocks for further transformations. We have focused on the investigation of gem-difluorination of carbon–carbon triple bonds, because this procedure is one of the most simple but powerful and straightforward methods. In addition, there have been a few reports in the literature that seem to mainly rely on

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• focused on their synthesis in the past decades [23][24][25][26][27][28][29][30]. These methods for the synthesis of β-keto thioesters include the mercaptolysis of diketene (Scheme 1a, path 1) [23], 2,2,6-trimethyl-4H-1,3-dioxin-4-one (Scheme 1a, path 2) [24], acylated Meldrum’s acids (Scheme 1a, path 3

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• 3 mL of methoxycyclopentane was pipetted directly onto the reaction solution. Then, the vial was capped with a rubber stopper. The methoxycyclopentane acted similarly to the diethyl ether in previous separatory methods by extracting the product from the DES. After letting the methyoxycyclopentane

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• key fragment [17][18][19][20][21][22][23][24][25][26]. The aforementioned features have led to an extensive development of novel methods to access meta-substituted anilines which can be divided into two main strategies (Scheme 1A) [27]. The first strategy focuses on the decoration of the aromatic ring

• ) substituent in the meta-position [38][39][40][41][42][43]. For example, several methods based on the Michael condensation–oxidation sequence starting from α,β-unsaturated ketones have been described (Scheme 1B) [44][45][46][47][48][49][50]. Recently, several methods have been developed based on the

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• substituted derivatives Alternariol: Alternariol (AOH, 1, Figure 4) was first isolated in the early 1950ies from Alternaria tenuis (synonymous with A. alternata). Its structure was elucidated with chemical analysis methods [33][54] and later unambiguously confirmed by X-ray crystallographic analyses [55][56

• ][68] and syntheses of labeled alternariol [69][70]. Selected syntheses will be given in the chapter on total syntheses (vide infra). The ubiquity and easy availability of this toxin by microbiological and synthetic methods (5 g of the compound were once synthesized in the group of the author) allowed

• than 500 entries to this compound. It was first isolated together with alternariol from Alternaria tenuis (synonymous to A. alternata) [33][54]. Its correct structure was proposed, based on chemical methods, shortly after [42] and was later unambiguously confirmed by total synthesis [62] and finally by

Finding the most potent compounds using active learning on molecular pairs

• Zachary Fralish and
• Daniel Reker

Beilstein J. Org. Chem. 2024, 20, 2152–2162, doi:10.3762/bjoc.20.185

• . Methods Datasets Datasets were obtained from Landrum et al. [23] which utilized their simulated medicinal chemistry project data (SIMPD) algorithm to curate and split 99 ChEMBL [24] Ki datasets with consistent values for target id, assay organism, assay category, and BioAssay Ontology (BAO) format into

• , Table S3). Random Forest and AD-XGB exhibited no statistically significant difference from each other (p = 0.2, Supporting Information File 1, Table S3). The increased diversity in selection from the deep models, that was heightened for our paired approach, highlights how methods that allow for

• optimization. Discussion Coinciding with increased enthusiasm for machine learning methods to support drug discovery [30][31], expanded use of adaptable laboratory automation [16][32][33] will help support adaptive learning methods like active machine learning to become a cornerstone technology to guide

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization

• Kateryna V. Dil and
• Vitalii A. Palchykov

Beilstein J. Org. Chem. 2024, 20, 2143–2151, doi:10.3762/bjoc.20.184

• never been used as enolizable carbonyl component in this chemistry. To the best of our knowledge only one compound from the target group was published (2003) [13] before this work, however, without any spectral evidence (Figure 1). Considering our constant interest in the development of methods for the

• ][4][9] or even visible light-driven methods [25][26][27][28]. We started our study from the optimization of the reaction conditions using β-ketosulfone 1, benzaldehyde and thiourea as model reaction. According to the literature, the reaction has been shown to work best and most efficiently under

• ]. We hope that compound 2r and its analogues obtained in this work can be further deeply studied by in silico and in vitro methods to discover the compound most suitable for clinical trials. The structures of the synthesized compounds 2a–r were confirmed by spectral data. The 1H NMR spectra of the

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

• , providing a cost-effective alternative to traditional catalytic methods. The immobilisation of organocatalysts offers the potential to increase catalyst reusability and efficiency in organic reactions. This article reviews the key parameters that influence the effectiveness of immobilised organocatalysts

• methods, such as the application of immobilised organocatalysts [14][15] and heterogeneous organocatalysis [16][17][18], could be a potential driver for the introduction of, for example, enantioselective organocatalysis in the pharmaceutical industry [19]. Knowledge of the factors that influence catalyst

• ]. The role of the polymers as supports for catalysts is not merely passive. These supports significantly influence the reaction environment and catalytic efficiency [42]. Attachment methods, spacer lengths, and polymer nature profoundly impact the catalyst's performance and recyclability. Various

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

• understand the conditions for the generation of heteroatom radicals. In addition, from the perspective of recent green chemistry, the development of environmentally friendly synthetic methods is strongly demanded. In other words, a new synthetic method should have excellent atom economy, produce no waste, be

• aware of resource recycling, and promote the use of natural energy [16]. The following three methods are generally used to generate heteroatom radicals (E•) (Scheme 1). In method 1, E• is generated by hydrogen abstraction from E–H by cyanoisopropyl radicals generated by thermal decomposition of 2,2

• on molecular transformations by the reactions of heteroatom radicals with isocyanides using methods 1 and 2. Thus, in this perspective, we mainly focused on the use of method 1 and method 2 for the generation of heteroatom radicals and the reactivity of them with isocyanides. Among these three

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

• simulations and analyse the corresponding results. The presented computational toolbox represents a valuable resource for researchers studying protein–glycan interactions and incorporates advanced computational methods for building, visualising and predicting protein/glycan structures, modelling protein

• , especially in bacterial glycans, makes the structural and conformational analysis of glycans extremely difficult, posing a considerable challenge when employing conventional structural biology methods for glycan analysis [10][12]. Nevertheless, understanding the three-dimensional structure of glycans is

• focused in the last decades on the development of new techniques and technologies for the systematic analysis of complex glycans and the study of their interactions with proteins. A multidisciplinary approach, spanning from wet laboratory experiments and biophysical techniques to bioinformatics methods is

Cage-like microstructures via sequential Ugi reactions in aqueous emulsions

• Rita S. Alqubelat,
• Yaroslava A. Menzorova and
• Maxim A. Mironov

Beilstein J. Org. Chem. 2024, 20, 2078–2083, doi:10.3762/bjoc.20.179

• Colloidosomes are microcapsules built on the basis of colloidal particles [1]. In the past 20 years, many methods have been proposed for the synthesis based on different particle types (inorganic, polymer, and composite) [2][3][4] and shape [5] (spheres, discs, and fibers). A distinctive feature of

• obtain colloidosomes covered with fissures of a controlled size [10]. A simpler method recently proposed involves the self-assembly of starch granules on the surface of emulsion droplets. However, this approach did not allow the pore size to be controlled [14]. Thus, the currently available methods for

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

• numerous other applications. The search for new and efficient syntheses of these heterocycles is therefore highly relevant. The modular concept of multicomponent reactions (MCR) has paved a broad alley to heteroaromatics. The advantages over traditional methods are the broader scope and increased

• intermediates undergo cyclization following a Michael addition to yield the corresponding pyrano[2,3-c]pyrazoles 63 (Scheme 20) [91]. Safaei-Ghomi et al. succeeded in isolating the intermediately formed pyrazole 64 [92]. Since pyrano[2,3-c]pyrazoles are fused heterocycles of interest, catalytic methods for

• ) cycloadditions with alkenes or alkynes to form pyrazoles, also in the sense of MCR. Furthermore, while not strictly classified as pericyclic reactions, hydrazones are also recognized as CN2 building blocks in pyrazole synthesis [169]. 1,3-Dipoles as key intermediates Various methods have been developed for the

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• appealing opportunities to take advantage of the versatility of this reagent. Such an approach can either ameliorate the previous methods in a more sustainable and efficient fashion or provide a mean for the discovery of new reactivity. Herein, this review aims to give an overview of the state of the art in

• FDA-approved drugs in the United States contain at least one azacycle [33]. Therefore, the development of gentle and efficient methods for accessing these heterocycles is an ongoing pursuit for synthetic chemists. As mentioned above, with their two nitrogen atoms, hydrazones constitute unique synthons

• electrochemical approach constitutes an advantageous alternative to previous methods, which required the preparation of difficult-to-handle hydrazonoyl halides for the synthesis of 1-aryl-5-amino-1,2,4-triazoles from cyanamide [56][57]. Pyrazolines are highly important heterocyclic motifs in pharmaceutical and

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• claimed to be a potential monomer for the preparation of new fluoropolymers [43][44]. Despite the fact that HFO-1132 has been known for a long time, there are no publications that summarize the chemistry of the compound. With this in mind, the main methods for the preparation of (E/Z)-1,2-difluoroethylene

• synthesis of 1,2-difluoroethylene based on perfluoropropyl vinyl ether as starting material can be found (Scheme 7). Consequently, two methods to prepare 1,2-difluoroethylene in the laboratory have been described to date. Even though at least five approaches to HFO-1132 can be found in patent literature, it

• the methods for the preparation of HFO-1132 as well as reactions demonstrating the chemical behavior of this compound. From the reactions not included in this Review article, mechanistic studies on 1,2-difluoroethylene ozonolysis [77][103][104][105][106][107][108] and studies on the stability of

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• , Parr and Yang developed a now widely used index of nucleophilicity from robust electron population methods such as NBO analyses, referred to as the Fukui index (f-) [44]. The larger the Fukui index, the greater the nucleophilicity, and is thus inversely proportional to the partial charge. Our

• yields from the same carbon sources through reagent control. Experimental General methods All materials were obtained from commercial suppliers and used without further purification unless otherwise noted. Anhydrous solvents were obtained from Sigma-Aldrich and used directly. Reactions involving air- or

• : Characterization of all compounds (1H NMR, 13C NMR, LC–MS, IR), and crystallographic methods and data for products P1 and P2. Supporting Information File 23: DFT methods, relative energy comparisons, TS imaginary frequencies, and XYZ coordinates. Supporting Information File 24: GoodVibes outputs. Acknowledgements