Search results
Search for "reactions" in Full Text gives 3157 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy
Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254
- molecular system. Herein, we present the synthesis of mono-, bis-, and tris-norbornadiene derivatives with alkynylbenzene and alkynylnaphthalene core units, along with studies of their photochemical properties. The target compounds were synthesized by Sonogashira–Hagihara coupling reactions of 2
- promising approach towards storage of solar energy is represented by the molecular solar thermal (MOST) energy storage systems, which have the ability to convert and store (sun)light energy in reversible photochemical reactions. Specifically, this approach is based on photoactive compounds that are
- spectra were observed. In the case of compounds 1j and 1n, the endpoint of the photoreaction could not be identified, as a steady decrease of the whole absorption spectra during irradiation indicated secondary decomposition reactions. We previously reported triplet energy transfer between 3[Ru(phen)3](PF6
Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond
Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253
- product biosynthesis, along with all the information an organism needs, are encoded in its genome. Genetic information is transcribed and translated into proteins that carry out chemical reactions that sustain life, which include both primary metabolism and the biosynthesis of natural products. Direct
- corresponding nucleic acid sequence. Proteinaceous enzymes then go on to catalyze biosynthetic reactions that put together small molecule building blocks (BB) to generate natural products with extremely diverse chemical structures. Because the intricacy of this process is not fully understood, scientists still
Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures
Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252
- molecule must be sufficiently long to penetrate the CD cavity and be available for the end-capping reactions, (3) the inclusion complex must dissolve appropriately, (4) the solvent must not decompose the inclusion complex (water or other polar organic solvents, such as dimethylformamide (DMF) and dimethyl
- substitution/addition reactions became the standard for end-capping reactions, although a transition metal–catalyzed cross-coupling reaction has also been used to synthesize CD-based rotaxane. Typically, water-soluble components are prepared, after which the Suzuki coupling reaction in water is used to
- synthesis, Harada and co-workers reported the end-capping reaction based on nucleophilic substitution by the amino groups on axle ends (Scheme 2) [43]. Similarly, other highly efficient reactions have been performed as end-capping reactions to produce polyrotaxane [13][14][15]. In addition to the simple
Advances in radical peroxidation with hydroperoxides
Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249
- . Keywords: C–H functionalization; oxidation; peroxidation; radical reactions; TBHP; Introduction Organic peroxides are used in many different areas of human activities. The traditional and most developed field is the use of peroxides as initiators in the polymerization process for the production of a wide
- development of efficient synthetic approaches to implement organic peroxide functionality in various substrates is a timely task. From the synthetic point of view, organic peroxides are one of the best sources of oxygen atoms for a variety of oxygenation reactions [6]. Hydroperoxides (especially TBHP), acyl
- mainly include: nucleophilic addition or nucleophilic substitution with H2O2 or ROOH [17][18], autoxidation with O2, pericyclic reactions of unsaturated bonds with O3 or O2, and metal-catalyzed peroxidation (Isayama–Mukaiyama hydrosilylperoxidation [19][20], for example) [21][22][23]. As the topic is
Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins
Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248
- –CH2–(CF2)n–COOCH3) with triflate as leaving group in terminal position are easily accessible and versatile building blocks for attaching long chain acids (pKa 0–1) to substrates in Williamson ether-type reactions. Keywords: acid-functionalized porphyrin; electron-rich porphyrin; nickel porphyrin
- ]. Beyond their essential biological roles, porphyrins and their derivatives are employed in a number of applications, acting as catalysts in numerous reactions, including oxidation, reduction, and cycloaddition [6][7][8][9][10]. Particularly when electron-rich porphyrins act as reducing agents, e.g. in
- electrocatalytic hydrogen evolution reactions, a proton source is needed [11]. In this context, trifluoroacetic acid is very frequently chosen as the proton source, because it is a strong acid but just not strong enough to destroy (demetallate) the Ni porphyrin [10]. Covalent attachment of acids facilitates proton
gem-Difluorovinyl and trifluorovinyl Michael acceptors in the synthesis of α,β-unsaturated fluorinated and nonfluorinated amides
Beilstein J. Org. Chem. 2024, 20, 2946–2953, doi:10.3762/bjoc.20.247
- blocks [26]. Despite the known instability of trifluoromethylated carbanions [27], their catalytic application has yielded valuable products [28][29][30]. gem-Difluoroalkenes and trifluoroalkenes are excellent acceptors in the Michael addition reactions. There are also known examples of the use of gem
- -difluoroalkenes and trifluoroalkenes in reactions with Grignard reagents [13][31]. Although, similar compounds are reported to be unstable molecules that are prone to decomposition under reaction conditions [32][33]. The goal of this work was the formation of gem-difluoro- and trifluorovinyl Michael acceptors by
- synthesis, e.g., via pericyclic reactions or nucleophilic additions. Results and Discussion We commenced our research by screening the nature of the base to generate carbanion at alpha position. We chose 2,3,3,3-tetrafluoro-N-heptylpropanamide, obtained according to the procedure developed earlier in our
Structure and thermal stability of phosphorus-iodonium ylids
Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245
- will stimulate the design and synthesis of new hypervalent iodine compounds, expanding the functionalisation reactions currently available through these useful reagents in organic synthesis. Structure and stability of hypervalent iodine compounds. Phosphorus-iodonium ylids investigated in this study
Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts
Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243
- concentrate on various arylation reactions involving carbon and other heteroatoms, encompassing rearrangement reactions in the absence of any metal catalyst, and summarize advancements made in the last five years. Keywords: arylation reaction; diaryliodonium salts; electrophilic arylation reagent; metal-free
- five to seven-membered cyclic compounds [47]. Arylation reactions using diaryliodonium salts can occur through four distinct mechanisms. First, the arylation can occur under metal-free conditions, involving the formation of a three-membered ring transition state through ligand coupling, leading to the
- upon binding of the enolate molecule to iodine either through a carbon–iodine or an oxygen–iodine bond. Both intermediates, I and II, are in rapid equilibrium with each other and further undergo two different types of reactions: [1,2]-ligand coupling and [2,3]-rearrangement (Scheme 2). Either of these
C–H Trifluoromethylthiolation of aldehyde hydrazones
Beilstein J. Org. Chem. 2024, 20, 2883–2890, doi:10.3762/bjoc.20.242
- reaction conditions, electron-enriched hydrazones provided the expected products in high yields (2a, 3a, 4a). Note, that in the case of the N-tosylhydrazone, further optimization reactions were required (for more details, see Supporting Information File 1), and reducing the temperature for the halogenation
- , alkenes) and halogens allowing an array of post-functionalization reactions. Finally, the trifluoromethylthiolation of molecules derived from compounds of interest was achieved to illustrate the synthetic utility of the method. Hence, the desired products 2v–x were efficiently isolated. To get more
- ), NBS (0.33 mmol, 1.1 equiv) in CH3CN (0.4 M), 20 °C, 10 min; then, AgSCF3 (0.6 mmol, 2.0 equiv), 2 h, under argon. a0.15 mmol reaction scale. bProduct 2v was isolated with an inseparable impurity. Mechanistic investigations and post-functionalization reactions. a19F NMR yields using α,α,α
Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions
Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241
- great attention in biomedical applications, clinical diagnostics, and conjugate materials. Keywords: cyclic imines; dibenzothiazepine; dibenzoxazepine; isocyanides; multicomponent reactions; pyrrole; triazolobenzodiazepine; Introduction Pyrroles and their derivatives are important N-heterocyclic
- /benzoxazepine/benzothiazepine is very important. Due to the wide applications of pyrrole-fused heterocycles, very diverse approaches have been developed for their synthesis [28][29][30][31][32]. In recent years, multicomponent reactions (MCRs) have emerged as one of the most efficient and powerful methods to
- achieve this goal [7][33]. Among them, isocyanide-based multicomponent reactions (I-MCRs) are one of the well-known strategies in this field due to their operational simplicity, one-pot, convergent properties and atom economy, high efficiency, and high levels of chemical selectivity [34][35][36]. In
N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity
Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240
- of n-propyl mercaptane with subsequent addition of acetic anhydride, pyridine and KHF2 afforded indigo-N-rhamnoside 5c as a 2:1 mixture of α/β-anomers. The relatively low yield is a result of side reactions and decomposition, due to the rather unstable nature of the product. The reaction of 5c with
- corresponding acetyl-protected N-glycosyl anilines with oxalyl chloride was not possible. The failure of this reaction can be explained by electronic deactivation of the aromatic ring and steric hindrance which resulted in competing Claisen-type side-reactions of the acetyl groups. However, reactions of
Multicomponent synthesis of α-branched amines using organozinc reagents generated from alkyl bromides
Beilstein J. Org. Chem. 2024, 20, 2834–2839, doi:10.3762/bjoc.20.239
- amines. Interestingly, whereas previously reported work describing the preparation and reaction of organozinc iodides in acetonitrile showed higher reactivity of secondary organozinc reagents over primary ones, reactions in THF in the presence of LiCl led to opposite results, with higher reactivity of
- bromides in order to explore their consecutive use in multicomponent Mannich reactions (Table 1). While our experience in the development of multicomponent reactions involving organozinc compounds prompted us to initially consider acetonitrile as probably the most adapted solvent for the whole process [26
Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates
Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238
- ] because of their easily modifiable dipeptide frameworks. Several methods exist for accessing PCPAs, such as the amination of 1-halo-1-alkynes [16][17], tandem reactions of α-imino esters with nucleophiles and electrophiles [18], and the nucleophilic addition of an acetylide to α-carbonylated N-acylimines
Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines
Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236
- spectroscopy, HPLC–HRESIMS) of the products of the investigated reactions unambiguously confirms the processes proceeding along routes A1 and B1 with the formation of N-aryl(alkyl)-7-oxo-5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidin-5-carboxamides 4a–i and N-aryl-2-(7-oxo-5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidin
Mechanochemical difluoromethylations of ketones
Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235
- efficiently converted to the target products under solvent-free conditions. The reactions proceed at room temperature and are complete within 90 minutes, demonstrating both efficiency and experimental simplicity. Keywords: ball milling; difluorocarbene; difluoromethylations; difluoromethyl enol ether
- ; mechanochemistry; Introduction In recent years, mechanochemical organic synthesis has been advanced significantly, prompting organic chemists to reconsider the necessity of solvents in their reactions [1][2][3][4][5][6][7][8][9][10][11]. Eliminating hazardous solvents substantially reduces the ecological
- footprint of organic reactions [12][13]. Beyond environmental benefits and enhanced human safety, mechanochemical reactions often feature shorter reaction times, eliminate the need for external heating, and offer alternative product selectivity [3][14]. In general, such reactions are characterized by the
C–C Coupling in sterically demanding porphyrin environments
Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234
- , Germany 10.3762/bjoc.20.234 Abstract Unlike their planar counterparts, classic synthetic protocols for C–C bond forming reactions on nonplanar porphyrins are underdeveloped. The development of C–C bond forming reactions on nonplanar porphyrins is critical in advancing this field of study for more complex
- ][25], Negishi [26], and Kumada [27] coupling reactions, as well as modern iridium and rhodium-based coupling techniques [28], are just some examples of the C–C bond formations that have been implemented to achieve complex substitution patterns and functional arrangements on porphyrins. Of these named
- coupling reactions, Suzuki–Miyaura couplings are known to be a robust tool when functionalizing porphyrins [29][30]. Many complex porphyrinoid architectures have been synthesized in this manner, from functional porphyrin arrays [31][32][33] to sterically challenging meso-substituted aryl bis-pocket
Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction
Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233
- ]. As a diastereoselective synthesis, reductive coupling reactions of commercially available 4-bromo-3,3,4,4-tetrafluoro-1-butene and glyceraldehyde 10a, its imine derivative 11, or Garner's aldehyde 10b have been reported [23][24]. Although the diastereoselectivities were low in some cases, the
- diastereomers 12 and 13 are often easily separable, and each diastereomer of optically active alcohols or amines can be obtained with an excellent optical purity (reactions 3 and 4 in Scheme 1). To the best of our knowledge, these are the only four works for the preparation of optically active substances having
- fluoroalkylated amines 15 with high optical purity could be easily prepared through [1,3]-proton shift reactions of optically active imines 14 which in turn were readily synthesized by condensation of various perfluoroalkyl ketones with optically active (R)-1-phenylethylamine (Scheme 2a) [25][26][27][28][29][30
Copper-catalyzed yne-allylic substitutions: concept and recent developments
Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232
- expand the scope of transition metal-catalyzed substitution reactions. Since its discovery in 2022, copper-catalyzed yne-allylic substitution has undergone rapid development and significant progress has been made using the key copper vinyl allenylidene intermediates. This review summarizes the
- terminal alkyne is the active species in the reactions. In this regard, merging the unique feature of Cu-catalyzed propargylic substitution with allylic substitution is a feasible solution to the challenge, which will represent a new sort of substitution reaction. From 2022, the Cu-catalyzed yne-allylic
- catalytic center; finally, the selectivity affording E-enyne and Z-enyne product is also an issue to be addressed, and possible side reactions need to be suppressed (Scheme 2). In this review, we summarize the recent development of copper-catalyzed yne-allylic substitutions. It is worth noting that when we
Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light
Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230
- : isocyanide; multicomponent reactions; one-pot reaction; oxidation; spiroindolenine; Ugi reaction; visible light; Introduction Diversity-oriented synthesis (DOS) is a successful approach to biologically active scaffolds directed to create an enormous exploratory space in pharmaceutical hit discovery [1][2
- spiro-heterocyclic indolenines from readily available starting materials under mild conditions and in a diversity-oriented fashion remains desirable. In this contest, oxidative isocyanide-based multicomponent reactions (oxidative IMCRs) can be considered as a convenient tool [15]. Actually, the use of
- efficient methods for the synthesis of heterocycles by multicomponent processes and domino reactions [16][17][18][19][20], here we disclosed the oxidative one-pot four-step synthesis of 2-amino-3,3’-spiroindolenines using readily available tertiary amines, electron-rich anilines and isocyanides as starting
Young investigators in natural products chemistry, biosynthesis, and enzymology
Beilstein J. Org. Chem. 2024, 20, 2720–2721, doi:10.3762/bjoc.20.229
- . Their privileged structures have led organic and bioorganic chemists to develop methods to construct them. Our fundamental knowledge in enzymology is continually expanded by enzymes involved in natural products biosynthesis, as their production requires evolved enzymes to perform chemical reactions
- clusters, and enzymes, development of chemical probes, biocatalysis and chemoenzymatic total synthesis, enzymatic mechanisms, and computational investigations of chemical structures and reactions. All of the major classes of natural products are represented here: nonribosomal peptides, ribosomally
Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones
Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228
- and Suzuki–Miyaura cross-coupling reactions followed by Brønsted acid-mediated cycloisomerisation. The developed methodology tolerates various functional groups and leads to moderate up to quantitative yields of the final products. The impact of different functional groups on the optical properties
- reactions (Figure 1). Polycondensed heterocycles containing a uracil moiety have also been studied in recent years. For example, compound A exhibits antitumor and antimicrobial properties (Figure 2) [66][67]. Compounds A and B are used as starting materials for the synthesis of polyaromatic derivatives of
- of palladium-catalysed Sonogashira–Hagihara and Suzuki–Miyaura cross-coupling reactions (Scheme 1). The final cyclisation step is accomplished by an acid-mediated cycloisomerisation. The synthesis of starting materials 4 was carried out by our previously reported protocol [65]. While compounds 4a–f
5th International Symposium on Synthesis and Catalysis (ISySyCat2023)
Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227
- ) derivatives, which possess recognized pharmacological properties [12]. They used sequential reactions catalyzed by palladium and copper. The process involves an initial amination, which can be carried out via either the Buchwald–Hartwig or the Chan–Lam reaction, followed by a palladium-catalyzed
- carbene (NHC) framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts, which demonstrated strong catalytic activity in gold-catalyzed alkyne hydration and arylative cyclization reactions [14]. The synthesis of this new carbene involved the use of a novel nitrenoid reagent that was
- successfully synthesized on a gram scale through a three-step reaction sequence. The process began with 2,6-diisopropylphenylamine, which underwent alkylation, formylation, and substitution reactions. The carbene synthesis was then achieved via a two-step process involving ynamide annulation, followed by
Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers
Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226
- fluoroenynes via Suzuki–Miyaura and Sonogashira cross-coupling reactions using novel multihalogenated fluorovinyl ethers, which are easily prepared from the reaction between phenols and 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane). These reactions make use of the unique structure of multihalogenated
- fluorovinyl ethers, which contains a reactive bromine atom, to afford a series of fluoroalkenes and fluoroenynes in moderate to high yields. Keywords: fluoroalkenes; fluoroenynes; multihalogenated vinyl ethers; Suzuki–Miyaura cross-coupling reactions; Sonogashira cross-coupling reactions; Introduction
- blocks. When using them as nucleophilic reagents [15][16][17][18][19][20], the reaction between anion species, such as fluorine-containing Horner–Wadsworth–Emmons reagents, and carbonyl compounds led to E-selective olefination (Scheme 1A) [15]. On the other hand, some reactions with electrophilic
Computational design for enantioselective CO2 capture: asymmetric frustrated Lewis pairs in epoxide transformations
Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224
- . These limitations suggest that a more viable approach to employing FLPs as catalysts for CO2-related reactions could involve their use in CO2 activation [7][18][19]. In particular, the capture of CO2 by FLPs enhances the electrophilicity of the CO2 carbon atom and the nucleophilicity of one of the CO2
- free energy correction at double-zeta. The kinetics of some reactions were calculated, applying the transition state theory [40]. Within this theory, the rate constant of an elementary reaction with the free energy barrier ΔG‡ is given by Equation 1, where k is the rate constant in s−1, kB is the
- favourable process. During the study, it will be observed that several transition states (TSs) can lead to the same product. As there is no possible interconversion between the reactant states, the different reactions will be considered independent, and it will be necessary to use an effective rate constant
Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones
Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223
- long time to complete. Hence, it was established that only those solvents which can produce hydroperoxides in situ were suitable for the reaction. Therefore, we chose Cs2CO3 as the base of choice, and performed the further reactions using 1.0 equiv of Cs2CO3 in THF at 50 °C in an open atmosphere
- NMR spectrum was consistent with the generation of tetrahydrofuran-2-hydroperoxide in THF, and was similar to the NMR reported earlier [25]. Further, the reaction of 3ba was scaled up to demonstrate the synthetic utility of our protocol. The reactions involving hydroperoxides are known to be difficult
- to scale-up due to their violent reactions at elevated temperatures. Our protocol involved mild conditions, and to our expectations, a gram-scale conversion of 3ba to 4ba proceeded smoothly without appreciable loss in the reaction yield (Scheme 3). The reduced reaction time and a lower reaction
Other Beilstein-Institut Open Science Activities
