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Search for "control" in Full Text gives 1540 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
pH-Controlled isomerization kinetics of ortho-disubstituted benzamidines: E/Z isomerism and axial chirality
Beilstein J. Org. Chem. 2025, 21, 1568–1576, doi:10.3762/bjoc.21.120
- barriers by protonation, providing a novel approach to control the kinetics of isomerization via pH adjustment. The results showed that protonation of the amidine moiety significantly suppresses both C–N bond rotation and C–N/C–C concerted rotation, demonstrating the potential of ortho-disubstituted
- triggered by protonation and deprotonation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. This class of molecules has the capacity to regulate three-dimensional structures and motions of molecules through simple acid–base stimuli. This provides a high degree of control over their
- of molecules that can precisely control the range of pH to which they can respond. Furthermore, it is also important to discover new molecular skeletons, as there is a lack of variation in the substructures that act as pH-responsive molecular switches. Previously, we reported that chalcogen
Facile synthesis of hydantoin/1,2,4-oxadiazoline spiro-compounds via 1,3-dipolar cycloaddition of nitrile oxides to 5-iminohydantoins
Beilstein J. Org. Chem. 2025, 21, 1552–1560, doi:10.3762/bjoc.21.118
- compounds in two-fold serial (50–100 μM) dilutions. Only DMSO + PBS (phosphate-buffered saline) was used as a control, since the studied compounds were soluble only in DMSO. Cell viability was measured using the standard MTT test [42]. Absorbance was measured at 540 nm using a Multiskan™ FC microplate
Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent CyreneTM under one-pot conditions
Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117
- -triazoles in a less toxic and recyclable medium could further control and reduce the environmental impacts of this synthetically very important transformation. Herein, we report a study on the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction in CyreneTM under mild conditions. Results and
General method for the synthesis of enaminones via photocatalysis
Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116
- while 3-iodochromone failed to provide the desired enaminone 9a (Table S7, Supporting Information File 1). Control experiments including the reaction in the absence of visible-light or photocatalyst, showed no product formation (Table 1, entries 16 and 17). Interestingly, the yield of 9a dropped to 30
Azobenzene protonation as a tool for temperature sensing
Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115
- different azo compounds [23][24][25]. More recent work has harnessed protonation to enable red-light switching [12][13][26] and to control the stability of the cis-isomer [27][28][29]. These studies have focused on how protonation affects isomerization, with less attention given on how external stimuli
- influence ion-pairing strength, offering a strategy to further control the protonation behavior and enhance the temperature-sensing performance. With improved understanding of azobenzene–acid interactions and good agreement between computations and experiments, a design-driven approach to temperature
Calcium waste as a catalyst in the transesterification for demanding esters: scalability perspective
Beilstein J. Org. Chem. 2025, 21, 1520–1527, doi:10.3762/bjoc.21.114
- linoleic acid (57.2%). Additional control experiments were performed with the original carbide slag (CS25) and commercial CaO, Ca(OH)2 and CaCO3 to confirm the main catalyst phase (CaO) as catalytically active species in the reaction and the results of the control experiments are summarized in Table 1
- . Reaction conditions: oil to alcohol molar ratio = 1:12, 1 wt % CS600, 65 °C, 2 h. Control experiments on the example of transesterification of soybean oil with methanol.a Supporting Information Supporting Information File 2: General information, experimental procedures, characterization data, and copies
Highly distinguishable isomeric states of a tripodal arylazopyrazole derivative on graphite through electron/hole-induced switching at ambient conditions
Beilstein J. Org. Chem. 2025, 21, 1496–1507, doi:10.3762/bjoc.21.112
- were subjected to control AFM experiments to check for any contamination or impurities on the surface. We also note that no traces of ethanol remained on the surface after pumping, as confirmed by AFM images. Instrumentation All AFM and STM measurements were performed using an Agilent 5500 in soft
Photoredox-catalyzed arylation of isonitriles by diaryliodonium salts towards benzamides
Beilstein J. Org. Chem. 2025, 21, 1480–1488, doi:10.3762/bjoc.21.110
- . Finally, control experiments without irradiation gave only traces of the benzamide 2aa showing no activation by the Ru complex at room temperature (Table 1, entry 24). An experiment conducted under an air atmosphere yielded only 9% of 2aa (Table 1, entry 25) indicating that the presence of atmospheric
- reactivity pattern in the current transformation, a reaction mechanism was proposed taking into the account the known data and control experiments (Scheme 4). Upon irradiation with blue light, the Ru(II) catalyst undergoes photoexcitation, followed by an oxidative single-electron transfer (SET) process with
- the iodonium salt, leading to the generation of an aryl radical, aryl iodide, and Ru(III). The formation of the aryl radical was corroborated through a trapping experiment utilizing TEMPO as a radical scavenger (Scheme 4 and Supporting Information File 1, 5. Control experiments, Figure S18). The
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- illustrating how subtle atomic substitutions can significantly influence the conformational stability of helical molecules (Table 19). These studies illustrate how precise heteroatom modulation enables fine control over CPL directionality and emission lifetimes, offering promising avenues for the development
N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B
Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103
- cell line are given below), after which the Alamar Blue cell viability reporter was added and the fluorescence recorded using an FLx 800 plate reader (BioTek) with excitation wavelength 535/540 nm and emission wavelength at 590/610 nm using Gen5 Reader Control 2.0 Software (BioTek). EC50 values were
High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters
Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102
- reactions were carried out at ambient pressure (control) and under HHP (up to 3.8 kbar) conditions. These representative reactions provided higher yields for the products and HHP enabled truly green processes that are catalyst- and solvent-free, to occur with high yields and producing only non-toxic by
- , thus the actual reaction mixture remains in a liquid state, making it ideal for HHP-assisted reactions. The first reaction in the optimization effort was the control experiment at atmospheric pressure. Under these conditions, no product formation was observed even after 10 h reaction time. However, 8
- parentheses. As shown in Table 4 and Scheme 4, the HHP reactions occurred at 50 °C with low to moderate yields, and with nearly quantitative yields at 80 °C. HHP reactions afforded the products in higher yields than those of the control experiments under the same conditions (time, temp. etc.) but only at 1
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- loadings were necessary for ortho-substituted phenyls. Control experiments and DFT calculations revealed that the oxetane ring is formed before the tetrahydrofuran in the domino process. In 2023, Shigehisa and co-workers published a new cycloisomerisation strategy for the construction of oxetane rings from
- after deprotonation of a suitably functionalised ether at the α-carbon. Therefore, a stabilising group must be incorporated to control regioselectivity of the deprotonation as well as to increase the acidity of the α-hydrogen. Mordini et al. showed that even weakly stabilising groups such as phenyl
- still runs smoothly, if the aryl is substituted for cyclohexyl. The proposed mechanism, supported by control experiments, deuterium exchange studies and energy calculations, consists of the following steps: conjugate addition of the carbene to the allenoate, regioselective addition of the resulting
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- ], medicine [3], sensing [4] and energy storage [5]. Typically, bulk graphene is obtained using a top-down approach, where graphite is exfoliated using chemical or mechanical methods [6][7]. However, this method does not provide precise control over the structure of graphene and graphenoid materials, which is
- crucial for fine-tuning their properties. An alternative is the bottom-up approach where various nanographenes are synthesized form smaller building blocks via classical organic synthesis. This strategy enables precise control over the structure and topology, leading to the development of a vast array of
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
- -substituents induced steric hindrance effects that led to lower yields. To gain further insight into the mechanism, several control experiments were performed. The results indicated that an iminoxyl radical is generated as the initiator of the reaction (Scheme 6). Initially, TBHP undergoes homolytic cleavage
- -3-phenylpropanenitrile (16ha), were successfully employed to construct the target polycycles. To verify the reaction mechanism, a series of control experiments were conducted. The complete inhibition of the reaction by radical scavengers such as TEMPO, BHT, and hydroquinone suggested a radical
- mechanism, control experiments were conducted. The addition of radical scavengers such as BHT and TEMPO significantly inhibited the reaction, confirming the involvement of a radical intermediate. Kinetic isotope effect (KIE) studies showed a KIE of 1.0, suggesting that C–H-bond cleavage was not the rate
Optimized synthesis of aroyl-S,N-ketene acetals by omission of solubilizing alcohol cosolvents
Beilstein J. Org. Chem. 2025, 21, 1201–1206, doi:10.3762/bjoc.21.97
- from in the process. For suppressing the formation of side products by self-condensation of S,N-ketene acetal intermediates the reaction temperature has to be kept as low as possible for assuring kinetic control. Therefore, in contrast to the standard protocol [5][6] (Scheme 2), reacting aroyl
- , kinetic control is warranted by conducting the condensation synthesis at room temperature for only short reaction times. Furthermore, 2-MeTHF was successfully implemented as a sustainable alternative to 1,4-dioxane. This modified protocol is clearly superior to the initial protocol (in 1,4-dioxane/ethanol
Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates
Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96
- isolated in 77% yield (1.3 g, 4.61 mmol). In order to propose the reaction mechanism, control experiments were conducted (Scheme 4). The reaction is completely inhibited by the addition of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) or BHT (Scheme 4, reaction 1). A BHT-adduct derived from a P-centered
- results and previous reports on copper(II) mediated oxyphosphorylation reactions [42][44][46][51][53], a plausible reaction mechanism is proposed (Scheme 5). The discovered transformation is unlikely to proceed via only a single route (see control experiments in Scheme 4), and the generation of phosphorus
- chromatography on silica gel. Recent approaches for the synthesis of β-ketophosphonates by the oxyphosphorylation of unsaturated compounds. The scope of the discovered copper(II)-mediated phosphorylation of enol acetates. Gram-scale synthesis of 3a. Control experiments. Proposed mechanism for copper(II) mediated
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- ]. Widespread use of 3D π-skeletons requires not only efficient construction of the skeletons but also functionalization with precise control of substitution numbers and positions. Along this line, fully π-fused [4.4.4]- and [3.3.3]propellanes [40][41][42][43] were able to be brominated and nitrated at six
- ][59][60]. This scheme also enables control of the number of formyl groups by starting materials and reagents. Brominated [4.3.3]propellane was reacted with n-BuLi or iPrMgCl·LiCl to generate an organometal species, which was quenched with N,N-dimethylformamide (DMF) as an electrophile (Table S201 in
- same protocol was successfully applicable to pristine π-fused [3.3.3]propellane [3.3.3], giving [3.3.3]_CHO selectively in 67% yield (Table 1, entry 3). In electrophilic aromatic substitutions, multifold reactions are possible, and the number of substitution is sometimes difficult to control by tuning
Synthetic approach to borrelidin fragments: focus on key intermediates
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- ]. Their method was based on the concept of “catalytic total synthesis”, wherein all stereocenters were installed under the control of catalysts. Minnaard and Madduri proposed the synthesis of the C1–C11 fragment from unsaturated thioester 92 through iterative, previously developed asymmetric 1,4-addition
Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines
Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74
- reduction with LiAlH₄, which led to a further decrease in the degree of unsaturation of the pyrazolodiazepine core, while the more sterically hindered exocyclic amide moiety remained intact. However, both reactions were accompanied by partial epimerization, and careful kinetic control was therefore required
Recent advances in controllable/divergent synthesis
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- review systematically examines, how these multidimensional control elements (including ligands, metal catalysts, solvents, time, temperature, acids/bases, and subtle modifications of substrates) synergize to achieve predictable product diversification. In addition, mechanistic insights are discussed
- control The precise regulation of product selectivity represents a fundamental challenge in transition-metal-catalyzed organic transformations, with significant implications for complex molecule synthesis. In this context, ligand-modulated divergent catalysis has emerged as a paradigm-shifting strategy
- , thereby offering unprecedented control over chemo-, regio-, and stereoselectivity parameters in catalytic manifolds. In 2015, the Jiang group developed a palladium-catalyzed regioselective three-component C1 insertion reaction (Scheme 1) [19]. In this reaction, an o-iodoaniline 1, phenylacetylene, and
Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes
Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71
- not result in the formation of the dimerization product and complex mixtures of products were observed in these cases. To gather insight into the reaction mechanism, several control experiments were performed (Scheme 3). We first observed that the reaction does not take place in the absence of B2pin2
- addition to a second molecule of 1. Given the negative results observed for other crotonate derivatives (Scheme 3c), coordination between the Li cation and the two chlorine atoms via proposed transition state D may be crucial not only for diastereoselective control but also for the viability of this step
- functionalized cyclopropane scaffolds depending on the nature of the carboxylic acid derivative. Chemodivergent reactivity observed in copper-catalyzed borylative couplings of allylic gem-dichlorides. Cu-Bpin-mediated dimerization of 4,4-dichoro-2-butenoic acid derivatives. Control experiments. Proposed
Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters
Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69
- , and control reactions support sensitization, enabling an intramolecular [2 + 2] cycloaddition to be realized accessing 3D bicyclic fragments containing a boron handle. Keywords: boron; catalysis; [2 + 2] cycloaddition; energy transfer; photochemistry; Introduction The strategic use of a photon to
- identify a suitable catalyst and boron residue, while control reactions and mechanistic studies support the proposed sensitization. The platform enables direct access to mono- and vicinal cyclobutylboronic esters that could be effectively derivatized to demonstrate their potential in synthesis. Results and
- solvent had a profound effect on reactivity with more Lewis-basic solvents suppressing reactivity (Table 1, entries 4 and 5 vs entries 6 and 7), indicating p-orbital availability plays a prominent role [56][57]. A control reaction (Table 1, entry 8), in combination with UV–vis absorption studies (see
Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation
Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68
- that a tripodal hexaurea receptor L (Figure 1b) could selectively and reversibly extract sulfate and phosphate anions from water into organic phase (under pH control) [30][31][32][33]. Single crystal structures of the receptor–K2SO4 complex in the presence of 18-crown-6 clearly displayed ion-dipole
Chitosan-supported CuI-catalyzed cascade reaction of 2-halobenzoic acids and amidines for the synthesis of quinazolinones
Beilstein J. Org. Chem. 2025, 21, 839–844, doi:10.3762/bjoc.21.67
- 96% isolated yield (Table 1, entry 12). Control experiments indicated poor results when no catalyst was used, with the corresponding product obtained only in 31% yield (Table 1, entry 13). When CuI or chitosan alone was used as a catalyst, the reaction occurred but with less efficiency (Table 1
Substituent effects in N-acetylated phenylazopyrazole photoswitches
Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66
- are molecules reversibly changing their optical and chemical properties upon irradiation. These features offer easy, precise, and reversible control over the system they are embedded in and make them attractive modulators for diverse applications. In the last decades, many classes of photoswitches
- -art technologies ranging from energy-storage materials [6][7] to pharmacology [8][9][10][11], materials chemistry [12][13], control of peptides structure [14][15] or proteins [16], as antibacterial agents [17][18], smart coating [19], or multivalent photoresponsive systems [20][21], to name only a few
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