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Search for "optimization" in Full Text gives 1148 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

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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  • . aReaction was done in DMF/AlCl3. bIsolation requires precipitation with 2-propanol. c2 days. Control experiments related to bulky substituted aldehydes. Optimization of the reaction conditions for the synthesis of 2a. Supporting Information Supporting Information File 28: Spectroscopic and analytical data
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Published 31 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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  • , provided the corresponding iodolactonization product in racemic form with a good yield (80% yield, 50:50 er) [36]. To improve the enantioselectivity in the asymmetric bromolactonization of 2a using NBP and catalyst (S)-1g, the optimization of reaction solvents was also performed. Based on our recent
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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

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  • the four-electron oxidation product 1,1-dimethoxynaphthalen-2(1H)-one (2). Best results were obtained with a carbon/platinum electrode pair, although stainless steel (SS) could also be used as cathode. The experiments were conducted with a 3:1 mixture of methanol/tetrahydrofuran (optimization not
  • process, there will always be some extra current passing the cell that does not contribute to the reaction. Our optimization of the current on 1-chrysenol (3b) is given in Table 2. The reaction mixtures were introduced via a 10 mL-injection loop into the stream that was flowing through the Flux cell at a
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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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  • for methyl malonyl-CoA and malonyl-CoA in the enzymatic conversions. After careful and systematic optimization of the reaction conditions, such as the stoichiometry of the PKS modules and pH, along with the application of a NADPH recycling system, JuvEIV/JuvEV-catalyzed enzymatic conversions of 77–79
  • classification, along with parallel discussions of the original biosynthetic pathways, helps organize the current state of the art and offers a comprehensive overview of how synthetic methodologies leverage the natural biosynthetic pathways. The development and optimization of chemo-enzymatic synthetic processes
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Published 23 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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  • proposed in the initial experiments is not a Lewis acid activator but just a chloride source. Further optimization studies improved the yield to 78% of 4b using a concentration of 0.20 M of the alcohol and 1.4 equiv of 1a (see Supporting Information File 1). Finally, all NHIs were tested under the
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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

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  • boronic monoester (18 → 19) followed by ring opening, in accordance to the hemiketal reactions. We decided to directly cleave dioxaborolane 20 after the reaction has stalled to facilitate separation. After a brief optimization of the reaction conditions (details are provided in Supporting Information File
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Published 19 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

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  • given SMILES string undergoes modifications to produce a list of SMILES for each deprotonated C–H bond. We generate min(1 + 3nrot, 20) conformers for each SMILES using RDKit (v.2022.09.4) [16][17], where (nrot) represents the number of rotatable bonds. Each conformer undergoes optimization in dimethyl
  • identify the lowest-energy conformer. We then conduct re-optimization in ORCA (v. 5.0.4) [22][23], using the dispersion D4-corrected DFT functional CAM-B3LYP [24][25], the Karlsruhe [26][27] triple-ζ basis set, def2-TZVPPD, and the conductor-like polarizable continuum model (CPCM) [28] as the implicit
  • methods are evaluated as single-point calculations or optimization and frequency calculations. For comprehensive details, refer to Supporting Information File 1, section “Benchmark study - computational methods”. Hereafter, we check the geometries for imaginary frequencies and use the total thermal energy
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Published 16 Jul 2024

Divergent role of PIDA and PIFA in the AlX3 (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

  • Kevin A. Juárez-Ornelas,
  • Manuel Solís-Hernández,
  • Pedro Navarro-Santos,
  • J. Oscar C. Jiménez-Halla and
  • César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

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  • protocol for the electrophilic bromination of arenes, mainly phenols [28][29]. Accordingly, the bromination reaction was initially explored by mixing PIFA and AlBr3, which gave an acceptable yield (84%). However, other iodine(III) reagents were tested as oxidants during the optimization process. Thus, when
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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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  • were degenerate (i.e., 10/11 and 14/15), reducing the number of distinct structures to 22. However, due to the considerable flexibility of the five-membered ring and the low barrier for pyramidal interconversion of the N–H moiety, some inputs converged to the same isomer post-geometry optimization
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Published 12 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

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  • the optimization studies mentioned above, the catalytic system I (15 mol %)/A5 (30 mol %) in CHCl3 (1 mL) at room temperature (30–32 °C) was selected as the optimum reaction conditions (Table 1, entry 12). Under identical optimized reaction conditions, the catalytic system II (15 mol %)/A5 (30 mol
  • measured by HPLC analysis using a stationary phase chiral column. Synthesis of 3aa on preparative scale. Proposed reaction mechanism. Optimization of reaction conditions.a Supporting Information Supporting Information File 2: Additional optimization studies, characterization data of compounds 3aa–na and
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Published 09 Jul 2024

Tetrabutylammonium iodide-catalyzed oxidative α-azidation of β-ketocarbonyl compounds using sodium azide

  • Christopher Mairhofer,
  • David Naderer and
  • Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1510–1517, doi:10.3762/bjoc.20.135

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  • mechanistic scenario. Application scope. Proof-of-concept for the analogous oxidative α-nitration. Optimization of the α-azidation of β-ketoester 1aa. Control experiments using different hypervalent iodine speciesa. Supporting Information Supporting Information File 24: Full experimental and analytical
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Published 05 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

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  • be less-suited for our azlactone protocol, as exemplified for derivative C1 (Table 1, entry 9). Accordingly, we carried out our final optimization using Maruoka’s catalyst B2 (Table 1, entries 10–14). By testing different bases and lower temperatures as well as lower catalyst loadings we identified
  • ammonium salt-catalyzed β-selective addition of compounds 2 to allenoates 3 (B), and the herein investigated β-selective addition of azlactones 1 to allenoates 3 (C). Application scope (conditions as detailed in Table 1, entry 13). Azlactone opening reactions. Optimization of the addition of azlactone 1a
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Published 04 Jul 2024

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

  • Yukang Wang,
  • Yan Yao and
  • Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

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  • plate as the cathode, was electrolyzed with a cell potential of 2.3 V (corresponding to an initial anodic potential of 0.10 V versus the ferrocenium ion/ferrocene redox couple) under the irradiation of 400 nm light-emitting diodes (LEDs). Through systematic optimization, we found that the use of readily
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Published 03 Jul 2024

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

  • Lu Li,
  • Na Li,
  • Xiao-Tian Mo,
  • Ming-Wei Yuan,
  • Lin Jiang and
  • Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

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  • delivered synchronously. Substrate scope of primary amines 3. Conditions: reactions conducted with 2 (0.2 mmol) and 3b–y (2.0 mmol) were stirred in DME (2 mL) at 60 °C; isolated yields. Gram-scale reaction and successive one-pot synthesis. Synthetic manipulation. Optimization studies.a Supporting
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Published 02 Jul 2024

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

  • Ziya Dağalan,
  • Muhammed Hanifi Çelikoğlu,
  • Saffet Çelik,
  • Ramazan Koçak and
  • Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

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  • used as nucleophiles. First, optimization experiments were carried out for fluoroalkoxy reactions with benzonorbornadiene (1a, Table 1). As a result of experiments conducted in six different solvents at room temperature with 1.0 equivalent of selectflor and 1.0 equivalent of methanol, it was observed
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Published 01 Jul 2024

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl2 and NH4SCN/KSeCN

  • Jialiang Wu,
  • Haofeng Shi,
  • Xuemin Li,
  • Jiaxin He,
  • Chen Zhang,
  • Fengxia Sun and
  • Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

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  • 3a and their derivatization. Plausible reaction mechanism. Optimization of oxidative thiocyanation of pyrazole.a Supporting Information Supporting Information File 28: Synthetic details and compound characterization data. Funding We acknowledge the National Key Research and Development Program of
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Published 28 Jun 2024

Challenge N- versus O-six-membered annulation: FeCl3-catalyzed synthesis of heterocyclic N,O-aminals

  • Giacomo Mari,
  • Lucia De Crescentini,
  • Gianfranco Favi,
  • Fabio Mantellini,
  • Diego Olivieri and
  • Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

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  • of a high water amount results in catalyst deactivation. Based on these results and what was observed in the optimization tests (Table 1, entry 6), we extended the reaction time but used ACN as solvent, which possesses a higher water content with respect to DCM (experiment C, Scheme 5). Gratifyingly
  • formation of N,O-aminals 5 and hemiaminals 6. Control mechanistic experiments. Optimization conditions for the Lewis acid-catalyzed intramolecular cyclization of 4a. Supporting Information Supporting Information File 16: General experimental information, synthetic procedures, analytical data and NMR
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Published 26 Jun 2024

Hypervalent iodine-catalyzed amide and alkene coupling enabled by lithium salt activation

  • Akanksha Chhikara,
  • Fan Wu,
  • Navdeep Kaur,
  • Prabagar Baskaran,
  • Alex M. Nguyen,
  • Zhichang Yin,
  • Anthony H. Pham and
  • Wei Li

Beilstein J. Org. Chem. 2024, 20, 1405–1411, doi:10.3762/bjoc.20.122

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  • cycle for the hypervalent iodine-catalyzed amide and alkene coupling. Hypervalent iodine-catalyzed olefin difunctionalizations background. Amide and alkene reaction optimization studies. Supporting Information Supporting Information File 14: Spectral characterization of the products and kinetic studies
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Published 24 Jun 2024

Synthesis of substituted triazole–pyrazole hybrids using triazenylpyrazole precursors

  • Simone Gräßle,
  • Laura Holzhauer,
  • Nicolai Wippert,
  • Olaf Fuhr,
  • Martin Nieger,
  • Nicole Jung and
  • Stefan Bräse

Beilstein J. Org. Chem. 2024, 20, 1396–1404, doi:10.3762/bjoc.20.121

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  • 50 °C. This optimization allowed for the isolation of the corresponding azides 19a–v in yields of 51% to quantitative (Scheme 2), usually with durations of 3–16 h. Longer reaction times were necessary for some CN-substituted triazene derivatives (19o, 19q, 19s, 19v), especially in combination with
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Published 20 Jun 2024

Synthetic applications of the Cannizzaro reaction

  • Bhaskar Chatterjee,
  • Dhananjoy Mondal and
  • Smritilekha Bera

Beilstein J. Org. Chem. 2024, 20, 1376–1395, doi:10.3762/bjoc.20.120

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  • . where they applied a FeCl3-based chiral catalyst with an N,N′-dioxide ligand [74]. The optimization of the reaction conditions revealed the L–RaPr2–FeCl3 complex being superior and delivering good to excellent results, thus witnessing a broad substrate scope taking different glyoxal monohydrates 1 and
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Published 19 Jun 2024

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

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

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

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  • hydrate a. Synthesis of products 6. Reaction conditions: 1 (0.5 mmol), hydrazine hydrate (1.5 mmol, 0.08 g), EtOH (5 ml). Proposed reaction mechanism for the formation of products 6. Synthesis of methylated product 7. Optimization of the reaction conditionsa. Supporting Information Supporting Information
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Published 11 Jun 2024

Transition-metal-catalyst-free electroreductive alkene hydroarylation with aryl halides under visible-light irradiation

  • Kosuke Yamamoto,
  • Kazuhisa Arita,
  • Masami Kuriyama and
  • Osamu Onomura

Beilstein J. Org. Chem. 2024, 20, 1327–1333, doi:10.3762/bjoc.20.116

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  • this transformation, iodobenzene was successfully converted to the corresponding product 3ka under slightly modified reaction conditions (see Table S1 in Supporting Information File 1 for optimization details). Under the modified conditions, aryl iodides with various electron-donating groups including
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Published 10 Jun 2024
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  • maleamic acid precursors. Optimization of IMDAF cycloaddition using different solvents.a Synthesized tricyclic epoxyisoindole-7-carboxylic acidsa. Supporting Information Supporting Information File 88: Tables S1 and S2, Cartesian coordinates of the optimized structures and copies of NMR spectra.
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Published 06 Jun 2024

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

  • Guoqing Cheng and
  • Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

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  • complexation, a significant red-shift of the dipyrrin band to 465 nm was observed due to the metal coordination with the dipyrrin moieties in 4b. To compare the structures of 1a and 1b, they are calculated through geometry optimization with the density functional theory (DFT) method. The alkyl chains at the
  • and their complexes with interlocking structures, respectively, after the geometry optimization with the GFN2-xTB method. The 45 different kinds of SWNTs with length of ≥3.0 nm and diameter range of 0.7–1.2 nm are chosen for the calculation (Table S1, Supporting Information File 1). The relationship
  • (Figure 5b). Computational methods The geometry optimization and frequency analysis of Cu-nanobrackets 1a and 1b were performed at (U)ωB97X-D/6-31+G(d,p)-SDD(Cu) [30][31][32][33] level using the Gaussian 16 program [34], with calculating the pre-resonance Raman activities at 488 nm excitation wavelength
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Published 05 Jun 2024

Phenotellurazine redox catalysts: elements of design for radical cross-dehydrogenative coupling reactions

  • Alina Paffen,
  • Christopher Cremer and
  • Frederic W. Patureau

Beilstein J. Org. Chem. 2024, 20, 1292–1297, doi:10.3762/bjoc.20.112

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  • 2,8-dimethoxy substitution (PTeZ15) allowed to significantly increase catalytic activity (3aa, 68% after 3 h), still at 1 mol % loading. Encouraged by this trend, which seemed to indicate that the more π-electron-donating substituents increase catalytic activity, we continued structural optimization
  • . Our future research efforts in the area of Te(II) catalysis will likely focus on milder coupling reactions on the one hand, and/or on novel more robust and more active ligand designs on the other. In particular, more investigations will likely be needed regarding the optimization of the possible Te
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Published 04 Jun 2024
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