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Search for "methods" in Full Text gives 2393 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

  • Matteo Gasparetto,
  • Balázs Fődi and
  • Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

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  • ]. The success of this technology ultimately relies on the quality and diversity of the libraries. DEL synthesis must employ DNA-compatible reactions; hence it operates under a limited set of conditions [4][5]. DELs are typically produced via split-and-pool combinatorial chemistry methods. Using
  • range of less widely applicable strategies have been developed as well [17][18][19][20][21][22]. The above-mentioned methods focus on the synthesis of α-alkyl-amino acids. Moving to α-aryl-amino acids, the Clayden group published an excellent asymmetric α-arylation method to access quaternary amino
  • with the Negishi cross-coupling step in a continuous flow manner [41][42][43]. Continuous flow chemistry offers superior control over reaction parameters compared to traditional batch methods. This approach leads to reproducible reactions, improved safety features, and it can facilitate high-throughput
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Published 08 Aug 2024

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

  • Ze-Nan Hu,
  • Yan-Hui Wang,
  • Jia-Bing Wu,
  • Ze Chen,
  • Dou Hong and
  • Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

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  • Medicus (Figure 1) [9]. Therefore, in recent years, isoquinolinone derivatives have attracted considerable attention, and successful synthetic methods involving the isoquinolinone framework have been reported. A number of appealing methods for the synthesis of isoquinolinone scaffolds using transition
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Published 07 Aug 2024

Novel oxidative routes to N-arylpyridoindazolium salts

  • Oleg A. Levitskiy,
  • Yuri K. Grishin and
  • Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

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  • -arylpyridoindazolium salts S1–S3 was confirmed with HRMS and 1H, 13C and 19F NMR data; the complete assignment of the signals was performed using 2D NMR methods. The N–N bond formation was additionally confirmed via comparison of the 1H spectra for the salts and their diarylamine precursors. The absence of the signals
  • A1, similarly to the chemical oxidation. The radical cation of dihydrophenazine formed was isolated and studied using ESR and HRMS methods. The ESR spectrum (see Supporting Information File 1) was typical for this type of compounds: a characteristic quintet due to hyperfine splitting on two
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Published 07 Aug 2024

Electrochemical radical cation aza-Wacker cyclizations

  • Sota Adachi and
  • Yohei Okada

Beilstein J. Org. Chem. 2024, 20, 1900–1905, doi:10.3762/bjoc.20.165

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  • photochemical reactions under acidic conditions, which were proposed to proceed via radical cations [20]. Since electrochemical and photochemical aza-Wacker cyclizations can offer ring systems that are difficult to construct through state-of-the-art palladium-catalyzed methods, the mechanistic understanding of
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Published 05 Aug 2024

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles

  • Ivan Lyutin,
  • Vasilisa Krivovicheva,
  • Grigory Kantin and
  • Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164

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  • versatile methods for the preparation of structurally diverse β-lactam derivatives is of great importance and relevance. Continuing the investigation of the reactivity and synthetic potential of diazotetramic acids (1), we have recently shown that these diazo reagents can act as precursors of β-lactam
  • (SLC6A19) [10]. Hence, developing new synthetic methods to create structurally diverse 2-oxoazetidine-3-carboxylic acid derivatives is a highly valuable endeavour that could have a positive impact on future drug discovery. Most synthetic approaches to amides and esters of 2-oxoazetidine-3-carboxylic acids
  • reported in the literature are based on the construction of the β-lactam ring (Scheme 1). The main methods include the [2 + 2] cycloaddition of acyl ketenes, generated by various methods, with imines [11][12][13][14] and the Wolff rearrangement of γ-amino-α-diazo-β-ketoesters followed by intramolecular
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Published 05 Aug 2024

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

  • Cristina Martini,
  • Muhammad Idham Darussalam Mardjan and
  • Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

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  • achieved during the last five years, and classifies them into five categories: synthetic methods, building blocks, scaffolds, biological activities and physical properties. Keywords: Groebke–Blackburn–Bienaymé reaction; multicomponent reactions; heterocycles; imidazo[1,2-a]pyridines; isocyanides
  • future perspectives of this reaction. Review 1 Novel synthetic methods The previously mentioned review, published in 2019 [1], had already highlighted how wide the variety of methods were used to conduct the GBB reaction: as much as 46 different catalytic systems had been reported in the literature at
  • (41–67%). Multicomponent polymerizations are simple and efficient methods to construct a library of polymers with great structural complexity and diversity, including fused-heterocyclic polymers[64]. Tang et al. [65] reported the transition-metal-free multicomponent polymerization of dialdehydes 96a–c
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Published 01 Aug 2024

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

  • Ivana Weisheitelová,
  • Radek Cibulka,
  • Marek Sikorski and
  • Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

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  • significant topic. Surprisingly, there has been limited information on 5-deazaalloxazines (dAll) synthesis [20][21][22]. Most known methods employ the cyclization of 6-(arylamino)uracils with one-carbon reagents such as triethyl orthoformate, dimethylformamide dimethylacetal, carbon disulfide, N,N
  • -dimethyldichloromethyleniminium chloride and the Vilsmeier reagent, or condensations between o-aminobenzaldehydes and barbituric acid [20][21][23][24][25][26][27]. Neither of these methods allows for the introduction of an aryl substituent into C(5), which confers unique chemical and physical properties on 5-aryldeazaalloxazines
  • -type syntheses, MCRs have become helpful tools for more efficient preparation of chemical libraries with higher molecular diversity and complexity in fewer steps and less time [28][29]. Considering the limitations of existing methods, as well as the applications of 5-aryldeazaalloxazines 2, and in the
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Published 31 Jul 2024

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

  • Sabyasachi Chakraborty,
  • Eduardo Mayo Yanes and
  • Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

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  • PAS chemical space is with data-driven methods, which have proven in the last few years to be extremely successful at uncovering underlying structure–property relationships. To enable such exploration, we initiated the COMPAS Project (COMputational database of PASs), the first database dedicated to
  • PASs and their molecular properties. The first installment, COMPAS-1 [6], contains ~35k cata-condensed polybenzenoid hydrocarbons (cc-PBHs) and has already enabled various directions of investigation, including by training of both interpretable machine [7] and deep learning methods [8], which led to
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Published 31 Jul 2024

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

  • Moisés Alejandro Alejo Hernandez,
  • Katia Pamela Villavicencio Sánchez,
  • Rosendo Sánchez Morales,
  • Karla Georgina Hernández-Magro Gil,
  • David Silverio Moreno-Gutiérrez,
  • Eddie Guillermo Sanchez-Rueda,
  • Yanet Teresa-Cruz,
  • Brian Choi,
  • Armando Hernández Garcia,
  • Alba Romero-Rodríguez,
  • Oscar Juárez,
  • Siseth Martínez-Caballero,
  • Mario Figueroa and
  • Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

Graphical Abstract
  • are derived from bacterial natural products (NPs), which have proven to be a valuable source of antimicrobial agents. During the latter part of the 20th century, the discovery of NPs was hindered by the limitation of traditional methods, which often led to the rediscovery of previously identified NPs
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Published 30 Jul 2024

Chiral bifunctional sulfide-catalyzed enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids

  • Sao Sumida,
  • Ken Okuno,
  • Taiki Mori,
  • Yasuaki Furuya and
  • Seiji Shirakawa

Beilstein J. Org. Chem. 2024, 20, 1794–1799, doi:10.3762/bjoc.20.158

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  • ; enantioselectivity; halogenation; lactones; organocatalysis; Introduction Catalytic asymmetric halolactonizations of alkenoic acids are powerful methods for the preparation of important chiral lactones in enantioenriched forms [1][2][3][4][5][6][7][8][9][10][11]. A wide variety of chiral catalysts have been applied
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Published 30 Jul 2024

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

  • Hiwot M. Tiruye,
  • Solon Economopoulos and
  • Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

Graphical Abstract
  • (PAHs) by cytochrome P450 (CYP) and other metabolic enzymes [7][8]. Main metabolic pathways form quinone isomers of benzo[a]pyrene [8], naphthalene [9][10], and benzene [11]. Numerous methods for the oxidation of phenols or their derivatives to quinones have been described [12]. Oxidation with Fremy’s
  • blocked like in 2-naphthol (1a) [17]. Oxidation with iodoxybenzoic acid (IBX) [17] or stabilised IBX (SIBX) [18] form o-quinones selectively, even when the p-quinones are structurally feasible. However, all these methods constitute toxic hazards and/or produce stoichiometric amounts of waste products
  • making them less desirable for industrial scale [19]. Electrochemical synthesis methods have a huge potential and this field is currently undergoing a renaissance [20][21][22][23][24]. Replacing chemical oxidants with electric current reduces waste production and gives a sustainable and inherently safe
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Published 24 Jul 2024

Syntheses and medicinal chemistry of spiro heterocyclic steroids

  • Laura L. Romero-Hernández,
  • Ana Isabel Ahuja-Casarín,
  • Penélope Merino-Montiel,
  • Sara Montiel-Smith,
  • José Luis Vega-Báez and
  • Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

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Published 24 Jul 2024

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

  • Ryo Tanifuji and
  • Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

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  • Ryo Tanifuji Hiroki Oguri Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 10.3762/bjoc.20.151 Abstract A steadily increasing number of reports have been published on chemo-enzymatic synthesis methods that integrate
  • intermediates from stable and achiral compounds, is complementary to chemical methods and is concise. In addition, adjusting the reaction environment with co-solvents and controlling the selectivity of subsequent dimerization may provide an avenue for the future design and application of more sophisticated
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Published 23 Jul 2024

A fiber-optic spectroscopic setup for isomerization quantum yield determination

  • Anouk Volker,
  • Jorn D. Steen and
  • Stefano Crespi

Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150

Graphical Abstract
  • εtrans/εcis is the highest, results in the formation of >95% cis-azobenzene [17]. The quantum yields (Φ) of isomerization of this process have been determined using different irradiation wavelengths, solvents, and methods [18][19][20][21][22][23][24]. One of the most interesting properties of azobenzene
  • of each isomer, as illustrated by Equation 1. The value for c at the PSS can be found using other spectroscopic methods, such as NMR spectroscopy [17] or the TEM (for Thulstrup, Eggers, and Michl) method [34][35]. With a known value for c, the spectrum of the second component can be found by a simple
  • kinetic model describing the components and the non-negativity constraint on the absorbance, can help to guide the decomposition of the data into chemically meaningful concentration traces and species-associated spectra (SAS) [38]. Global and target analysis is one of the methods employed in recent
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Published 22 Jul 2024

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ3-iodanes

  • Thomas J. Kuczmera,
  • Pim Puylaert and
  • Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

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  • easily overoxidized to carboxylic acids. Over the past decades a variety of methods have been developed, utilizing toxic heavy metals such as pyridinium dichromate (PDC) [3][4][5] or manganese dioxide (Figure 1) [6][7]. Molecular oxygen [8] and peroxides [9][10] can also be used as inexpensive terminal
  • oxidants in combination with transition-metal catalysts. Metal-free methods employ chlorodimethylsulfonium compounds as the reactive species and have gained great popularity under the name Swern oxidation or the Corey–Kim oxidation [11]. Hypervalent iodine compounds have also been studied and are well
  • optimized conditions, revealing the tetrazole-substituted iodane 1a to be the best oxidant for this reaction (Table 2). The two suitable methods (A: HCl in EtOAc; B: TBACl in MeCN) were then applied to a variety of activated alcohols. The best option is shown in Figure 5. Model substrate 4a could be
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Published 19 Jul 2024

Ring opening of photogenerated azetidinols as a strategy for the synthesis of aminodioxolanes

  • Henning Maag,
  • Daniel J. Lemcke and
  • Johannes M. Wahl

Beilstein J. Org. Chem. 2024, 20, 1671–1676, doi:10.3762/bjoc.20.148

Graphical Abstract
  • strain; Introduction Identifying efficient methods for the preparation of densely functionalized molecules is one of the central goals of modern organic chemistry. In this context, application of strained molecules has garnered increasing attention due to their intrinsic reactivity [1][2]. However
  • , accessing strained molecules continues to pose a synthetic challenge because many reported methods require harsh conditions for the preparation. An attractive alternative to traditional synthesis can be found in photochemical methods, bypassing energetic constraints by the utilization of photon energy. Thus
  • by Norrish–Yang cyclization, which employs easily accessible α-aminoacetophenones as starting materials [11][12][13][14][15]. Furthermore, ring-opening reactions of azetidines have been recently achieved using sulfur and oxygen nucleophiles [16][17][18][19][20][21][22][23][24][25]. However, methods
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Published 19 Jul 2024

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

  • Maria-Paula Schröder,
  • Isabel P.-M. Pfeiffer and
  • Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

Graphical Abstract
  • [34]. In reductive amination, the substrate is usually an aldehyde or amine. After the formation of the iminium ion, it is reduced with the appropriate reagent to form the N-methylated amino acid. Different methods have been established using for example benzaldehyde as a protection group, sodium
  • cyanoborohydride as a mild reducing agent, and paraformaldehyde as a methylating agent [36]. Methanol can be used as the methylating reagent in other methods. Here, a palladium on carbon (Pd/C) catalyst processes the dehydrogenation of the alcohol to form the corresponding aldehyde. The subsequently formed imine
  • -methylation concurrently to peptide synthesis is also possible. Commonly used methods for SPPS of N-methylated peptides involve activating the amino group with 2-nitrobenzenesulfonamide and methylating agents, such as dimethyl sulphate [40][41][42]. Directly methylating peptides is challenging. Multiple amide
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Published 18 Jul 2024

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

  • Fátima C. Teixeira,
  • António P. S. Teixeira and
  • C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

Graphical Abstract
  • observed for Nafion doped membrane with compound TP2, with a 1.0 wt % loading, with 84 mS·cm−1. Experimental Materials and methods Cyanuric chloride (1) and diethyl (4-aminophenyl)methylphosphonate (17) are commercially available (Sigma-Aldrich, Alfa Aesar). Other acquired reagents and deuterated solvents
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Published 17 Jul 2024

pKalculator: A pKa predictor for C–H bonds

  • Rasmus M. Borup,
  • Nicolai Ree and
  • Jan H. Jensen

Beilstein J. Org. Chem. 2024, 20, 1614–1622, doi:10.3762/bjoc.20.144

Graphical Abstract
  • bond to create new connections has attracted increasing interest [1]. While past methods allowed for C–H transformations in simple molecules, recent synthetic protocols [2] enable selective C–H activation and diversification in larger molecules. This has, for example, attracted the pharmaceutical
  • quantum chemistry (QM)-based workflow for the automatic computation of C–H pKa values in DMSO. The computed C–H pKa values are then used to generate training data for an ML model using LightGBM [6]. The QM-based workflow and the ML model are freely available under the MIT license. Methods Datasets We
  • solvation models. CAM-B3LYP is chosen as the optimal functional based on a benchmark study that evaluates the accuracy of different levels of theory, ranging from semiempirical methods (xTB) [21] over composite electronic structure methods (r2SCAN-3c) [29] to DFT methods (CAM-B3LYP) [24][25]. All these
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Published 16 Jul 2024

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

  • Evgen V. Govor,
  • Vasyl Naumchyk,
  • Ihor Nestorak,
  • Dmytro S. Radchenko,
  • Dmytro Dudenko,
  • Yurii S. Moroz,
  • Olexiy D. Kachkovsky and
  • Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

Graphical Abstract
  • compared for 24 library members that we attempted to obtain by both methods (Figure 2). These preliminary experiments also allowed establishing the following limitations of the method and excluding the corresponding reactants from further studies (Figure 3): α-aminoazoles of varied electronic nature (e.g
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Published 16 Jul 2024

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

  • Ka-Lung Hung,
  • Leong-Hung Cheung,
  • Yikun Ren,
  • Ming-Hin Chau,
  • Yan-Yi Lam,
  • Takashi Kajitani and
  • Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

Graphical Abstract
  • DAn stock solutions [61] and the fabrication of macroscopic scaffolds followed the standard methods outlined above. An aqueous solution of DAn (5.0 wt %) was manually added to a calcium chloride solution (150 mM) in a bioinert surface dish to fabricate the macroscopic scaffold. After removal of the
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Published 15 Jul 2024

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

  • Ana Flávia Candida Silva,
  • Francisco A. Martins and
  • Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

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  • pyrrolidinium salt [11] with the CCSD/DGTZVP geometry of the pyrrolidinium cation (with an exclusively axial C–F bond) and the energy of 3-fluoropyrrolidine conformations. Various combinations of DFT methods (B3LYP-D3BJ, ωB97XD, and PBEPBE) and basis sets (DGTZVP and 6-311++G**) were evaluated. The selection of
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Published 12 Jul 2024

Benzylic C(sp3)–H fluorination

  • Alexander P. Atkins,
  • Alice C. Dean and
  • Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

Graphical Abstract
  • , over recent years much attention has been focused on C(sp3)–H fluorination, and several methods that are selective for benzylic C–H bonds have been reported. These protocols operate via several distinct mechanistic pathways and involve a variety of fluorine sources with distinct reactivity profiles
  • incorporate fluorine into compounds of interest, with regio and site selectivity pre-determined by the nature of the functionalised carbon. However, the development of C(sp3)–H fluorination methods represents a more sustainable and versatile approach, as there is no requirement to pre-functionalise the
  • authors displayed the stability of the secondary benzyl fluoride 9 to various SNAr conditions. While these methods demonstrate excellent application of palladium catalysts to perform benzylic fluorinations, the need to install a directing group can limit substrate scope. Therefore, methods that can
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Published 10 Jul 2024

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

  • Pooja Goyal,
  • Akhil K. Dubey,
  • Raghunath Chowdhury and
  • Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

Graphical Abstract
  • , and the desired product 3ch was obtained in 87% yield and 90% ee. In general, enantiomers of a bioactive molecule have different biological activities. Therefore, there is a huge demand to develop methods to access both enantiomers of a chiral compound. We turned our attention to the synthesis of
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Published 09 Jul 2024

Towards an asymmetric β-selective addition of azlactones to allenoates

  • Behzad Nasiri,
  • Ghaffar Pasdar,
  • Paul Zebrowski,
  • Katharina Röser,
  • David Naderer and
  • Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

Graphical Abstract
  • synthesis approaches. Our group has a longstanding focus on the development of asymmetric organocatalytic methods to access non-natural chiral α- and β-AA [14][15][16][17][18][19]. Hereby we are especially interested in utilizing simple (prochiral) starting materials and carry out stereoselective α
  • in a straightforward manner. Conclusion The development of novel catalytic methods for the asymmetric synthesis of non-natural amino acid derivatives is a contemporary task and we herein introduce an organocatalytic protocol for the β-selective addition of various azlactones 1 to allenoates 3. Upon
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Published 04 Jul 2024
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