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Search for "reactivity" in Full Text gives 1556 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction
Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256
- studies, we employed benzaldehyde derivatives with various stereoelectronic decoration, excluding aliphatic ones due to their decreased reactivity resulting in failures to proceed [24][25][26][27]. Commercially available isocyanides utilized were cyclohexyl and tert-butyl isocyanide. Notably, an isolation
Enantioselective regiospecific addition of propargyltrichlorosilane to aldehydes catalyzed by biisoquinoline N,N’-dioxide
Beilstein J. Org. Chem. 2024, 20, 3069–3076, doi:10.3762/bjoc.20.255
- systematic catalyst structure–reactivity and selectivity relationship study. The observed catalyst structure–enantioselectivity relationship of the present allenylation reaction was found exactly opposite to that of the analogous allylation reaction. The method provided eleven α-allenic alcohols in 22–99
- ][15][16][17][18][19], the separation of which is by no means trivial [20] (Scheme 1). Nonetheless, substituents at the carbon atom indicated by γ (R2) of these reagents have been shown to bias the metallotropic rearrangement and/or the kinetic reactivity of the competing regioisomeric intermediates
- stable allenyltrichlorosilane that affords undesired homopropargylic alcohols [35][36] (Scheme 2b). Furthermore, Iseki [35] and Nakajima [36] evaluated only one chiral catalyst in their independent studies (i.e., no catalyst structure–reactivity and selectivity relationship study). In this context, we
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
- structure of a molecule defines its properties and reactivity, and therefore dictates how it interacts with other molecules. Microorganisms need to communicate with each other and the environment, secreting signals of friendship, disdain, and many other sentiments in between. Natural products are the
Advances in radical peroxidation with hydroperoxides
Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249
- , either by themselves or with the aid of metal complex catalysis, and to provide an insight into the reactivity of these species. The present work is divided into sections, according to the type of the substrate: C(sp3)–H substrates; aromatic systems; compounds with unsaturated C–C or C–Het bonds. The
- involving radical intermediates from hydroperoxides under redox conditions (Scheme 3). The reactivity of O-centered radicals is less predictable and more diverse depending on radical structure and substrate pattern than the chemistry of C-centered radicals [29][30]. Generally, peroxy radicals have a
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
- Poznań, Poland 10.3762/bjoc.20.247 Abstract The incorporation of fluorine atoms within the structure of organic compounds is known to exert a significant impact on their electronic properties, thereby modulating their reactivity in diverse chemical transformations. In the context of our investigation
- characteristic (Table 1, entry 7). A slightly higher reactivity was achieved when the BF3·(OEt2) was used instead of TiCl4 (Table 1, entry 8) [28]. The reactions were monitored by 19F NMR of the crude mixtures. The full conversion was reached by applying exclusively n-BuLi, but the formed product was not the
Structure and thermal stability of phosphorus-iodonium ylids
Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245
- synthetic organic chemistry, becoming indispensable tools in total synthesis, late-stage functionalisation and radiolabelling [1][2][3][4][5][6][7][8][9]. Due to their great mechanistic flexibility, including reactivity as oxidants, electrophiles, radical precursors and transmetalating agents, they often
- vital to gain a fundamental understanding of the structural factors affecting their stability and reactivity. Previous reports have suggested a link between structural factors and thermal stability of hypervalent iodine compounds [10][11][12][13][14][15][16]. Iodine(III) compounds are generally trigonal
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
- arylation; rearrangement reaction; Introduction The chemistry of hypervalent iodine compounds is well-established and they are prevalent as oxidants and electrophilic reagents in organic conversions [1][2][3]. They have gained significant attention due to their high reactivity and ability to carry out
- ]. They offer several advantages over traditional reagents, including low toxicity, high reactivity, and excellent selectivity [43] under simple reaction conditions. The distinctive reactivity of DIAS enables the smooth arylation of various carbon and heteroatom nucleophiles under gentle conditions, with
- (Scheme 17) suggests that the reaction initiates with an SNAr at the ortho-carbon, forming a Meisenheimer complex I and a novel iodine(III) intermediate II. This type of reactivity is unprecedented, as past reactions between nucleophiles and diaryliodonium salts usually lead to a reduction of iodine(III
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
- for this reaction. By replacing cyclohexyl isocyanide with tert-butyl- and isopropyl isocyanide, the corresponding products were obtained with similar yields. To investigate the reactivity of other cyclic imines in this protocol, we performed the reaction of triazolobenzodiazepine with gem-diactivated
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
- organometallic Mannich couplings involving nonstabilized organometallics are uncommon and mostly limited to dialkylzinc reagents, likely due to their commercial availability, their significant reactivity, and their functional-group tolerance [7][8][9][10]. However, the molecular diversity accessible with these
- alkyl iodides [24]. It was indeed noticed that the reactivity of primary iodides in the multicomponent carbonyl alkylative amination (CAA) reaction was quite sluggish compared to the secondary counterparts. In addition, primary alkyl bromides were found to be almost inactive in the process. Therefore
Mechanochemical difluoromethylations of ketones
Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235
- absorption of mechanical energy and they are influenced by several factors, including the lack of solvation, changes in morphology and rheology of the reaction mixtures during the milling, and variations in concentration and dielectric environment. Consequently, an increased reactivity can be achieved
C–C Coupling in sterically demanding porphyrin environments
Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234
- porphyrins [34] and tetrabromoanthracenyl porphyrins [35]. In general, the halogen atom needed for the Suzuki coupling reaction resides on the porphyrin; however, Suzuki–Miyaura reactivity has also been shown to be reversed whereby the synthesis of borolanylporphyrins leads to a different approach to
- reactivity [36]. Borolanylporphyrins can be synthesized by Miyaura-borylation of the halogenated porphyrin [24][37]. There are also reported instances of borolanylporphyrins being synthesized under condensation conditions [36][38]. Despite the many synthetic advancements for the decoration of porphyrins
- the starting material porphyrin 13 being left unreacted. On switching the substrate from boronic acid to the boronic acid ester and opting for the weaker base Cs2CO3 instead of K3PO4, a significant difference in reactivity was observed with a 72% yield accomplished in the synthesis of porphyrin 29
Copper-catalyzed yne-allylic substitutions: concept and recent developments
Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232
- various nucleophilic reagents further hampers the reactivity of coumarins. Xu, Peng and Feng et al. [70] introduce a groundbreaking dual remote enantioselective copper-catalyzed yne-allylic substitution methodology tailored specifically for coumarins (Scheme 21). This innovative approach facilitates the
- yne-allylic cation intermediate, followed by an intramolecular cyclization. The disparity in reactivity could stem from the chelation between acyclic 1,3-dicarbonyl enolates and the copper catalyst, enhancing γ-position attack in an intramolecular manner. Conversely, Meldrum's acid's rigid cyclic
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
- , particularly given the increasing levels of CO2 in the atmosphere. However, challenges persist in understanding and optimising the reactivity of these systems. One significant obstacle is the tendency for CO2 to react preferentially with FLPs over H2. As such, the design of FLPs that prioritise the capture of
- (keff). The definition given by Williams will be used (Equation 3, [42]): The proton affinity (PA) [43] of the LB and the fluoride ion affinity (FIA) [44] of the LA of a given FLP are generally used to rationalise the FLP reactivity observed [45][46]. Thus, PA and FIA of the different scaffolds
- centres are indicative of the FLP’s reactivity [45][46]. Thus, substituents must be selected to ensure a broad spectrum of acidity and basicity of the LA and LB. Different methods for determining these properties have been described in the literature. Because of their easy computation, the proton affinity
A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis
Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214
- C–H hydroxylation process by combining continuous flow chemistry and electrochemistry (Scheme 8) [16]. The surface modification of electrodes can lead to improved reactivity and selectivity. In this regard, Li and coworkers developed electron-deficient W2C nanocrystal-based electrodes to enhance the
- undergoes hydrogen-atom transfer (HAT) leading to alkyl radical formation. The manganese-catalyzed azide radical transfer then delivers the product. Unactivated secondary and tertiary C–H bonds, as well as benzylic C–H bonds, were prone to azidation, with the reactivity order being: benzylic > tertiary
Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams
Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210
- in Scheme 2. Unfortunately, the substrates 8a,b displayed low reactivity due to their significantly higher oxidation potential compared to the excited photoredox catalysts (>2.5 V vs SCE) [49]. However, other derivatives exhibited a satisfactory product yield ranging from moderate to good. Substrate
Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols
Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209
- become increasingly popular in recent years probably due to their useful reactivity, ease of handling, and low toxicity [13]. In particular, hypervalent iodine compounds have been shown to be effective reagents and catalysts for a range of cyclization reactions [14]. In 2015, we reported the iodoarene
Phenylseleno trifluoromethoxylation of alkenes
Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207
- )benzene (DNTFB) [66][67]. This DDPyOCF3 solution has shown a good reactivity to obtain various fluorinated compounds and especially trifluoromethoxylated molecules [68][69][70][71]. As another chapter of this research program, we propose here an easy and complementary access to CF3O-substituted alkyl
Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles
Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206
- -to-handle reagent, NaOCl·5H2O. Because very little has been disclosed about the reactivity of such 2,3-epoxyesters, their epoxy ring opening by a variety of nucleophiles was carried out and we succeeded in clarifying these chemo- as well as regioselective processes proceeding via the SN2 mechanism to
- organometallic species [16][17][18][19]. At least in part, its high reactivity was considered to be due to the significantly lower-lying LUMO energy level by the attachment of electron-withdrawing trifluoromethyl (CF3) and ethoxycarbonyl groups [20]. As we previously pointed out [10][21], the effective
- like to describe in detail the results of the preparation of epoxyesters 2 with various Rf groups as well as their reactivity with diverse nucleophiles [39]. Results and Discussion Preparation of (E)-2,3-epoxypropanoates 2 with Rf groups at the 3 position Because the urea·H2O2 complex proved its
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- boroxine with dramatically increased reactivity towards C=N electrophiles. Because of the small steric size of the (BO2) group, the reaction is highly selective towards (E)-α-trifluoromethyl homoallylic amine 44, which otherwise is difficult to obtain in a regiospecific manner. It has to be noted though
- acid activation mode appears to be the most plausible. Interestingly, chiral phosphoric acids failed to catalyse this reaction, but the use of chiral sulphonimide 45 afforded 82–97% ee and 65–84% yield on a set of aromatic and aliphatic aldehydes. The low reactivity of the allyltrimethylsilane (46
- analogues, a novel tetrakis-triazole-based H-bond donor catalyst 111 was identified as most promising. Among different nucleophilic allylating reagents, 2-methallyltributyltin (107) emerged as optimal in terms of reactivity and enantioselectivity. It was speculated that the enantioinduction is realised via
Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers
Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199
- –protein conjugates are reacted via CuAAC with an azide tag. While the CuAAC has been employed in various studies and has had large impact on many biological discoveries, an unspecific reactivity was often reported [54][64]. Recently, we described this background-forming reaction, which is based on an
- alkyne probe from the CuAAC reaction mixture or by increasing the concentration of the reducing agent such as tris(2-carboxyethyl)phosphine (TCEP). The reversed chemical proteomics approach in which the azide probe and alkyne tag are used suffers from similar unspecific reactivity of the terminal alkyne
- of the probe is necessary to identify any unspecific bands stemming from side reactivity of the azide–protein conjugate. In case a photo-crosslinker is used, another control experiment needs to be included, in which the cells/lysate are treated with the probe but not UV-irradiated. The non-covalent
Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines
Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198
- catalysis with hydrogen bonding units has been essential for achieving high reactivity and enantioselectivities [21][22]. Additionally, the reactivity of the nucleophilic addition is influenced by substitutions near the electron-poor double bond. This approach requires 30 mol % of catalyst and a reaction
- enhancing the reactivity of a relatively inert acceptor does not necessarily lead to increased reaction rates, involves the use of more reactive nucleophiles. In this context, varying the stabilization energy of carboxylic acid derivatives by switching from oxoesters to thioesters is the significant
- reactivity by chiral quaternary ammonium salt in the asymmetric variant of the phase-transfer catalysis. Nevertheless, no product was formed despite several conditions being examined. Finally, an attempt to activate the electrophile was performed. We chose iminium salt catalysis particularly employing chiral
Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes
Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197
- catalysts or photochemical procedures have been developed to enable this transformation [7][8][9]. The reactivity of hypervalent iodine reagents can be enhanced via Lewis acid catalysis [10]. For example, PIDA becomes a stronger oxidant upon coordination of BF3·OEt2, enabling chemistry that was not
- described in some group-transfer schemes [23][24][25], and in particular, fluorinated alcohol solvents, such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), have been reported to enhance hypervalent iodine reactivity by providing a H-bonding solvent cluster that enhances the electrophilicity of the iodine
- recently developed a metal-free aziridination of unactivated olefins via the intermediacy of an N-pyridinium iminoiodinane (Scheme 1b) [34]. We rationalized the enhanced reactivity towards olefin aziridination as a result of charge-enhanced iodine-centered electrophilicity arising from the cationic N
Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis
Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196
- , equipping experimentalists with the knowledge necessary to follow the developments in the field. The rest of the review is divided into three parts: (1) ML for reactivity and selectivity prediction, (2) ML for the design of privileged organocatalysts and (3) ML for catalyst and reaction design. Ultimately
- , the authors developed a separate model to gain a sufficiently interpretable model, finding that some parameters remain important throughout the different subsets. This example demonstrates both the strength of careful data analysis and the intricacies of dealing with chemical reactivity data. The
- . With HTE platforms established and due to their importance to ML campaigns, the past few years have seen a trend in creating larger experimental chemical reactivity datasets, in particular for transition metal catalysis [47][48]. 2.2 Increasing data availability in ML for organocatalysis While, to the
Deuterated reagents in multicomponent reactions to afford deuterium-labeled products
Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195
- scope of reactivity and determination of deuterium retention using a combination of deuterated aldehydes, [D1]-, and/or [D2]-isocyanides. We began with the venerable Ugi 4-component reaction (Ugi-4CR), first reported by Ivar Ugi in 1959 [28]. The Ugi-4CR utilizes an amine, carbonyl, carboxylic acid, and
- the Passerini reaction [40][41][42][43] discovered 60 years prior to the Ugi reaction. It uses the reactivity of isocyanides, aldehydes, and carboxylic acids to yield α-acyloxy amides (Scheme 6). Six deuterated analogs are reported in good yield with no observation of deuterium scrambling. For the
Synthesis and reactivity of the di(9-anthryl)methyl radical
Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193
- , electrical properties, and reactivity. The generation of the DAntM radical was confirmed by its ESR spectrum, which showed two broad signals. The unpaired electron is primarily localized on the central sp2 carbon and slightly delocalized over the two anthryl moieties. Although the DAntM radical undergoes
- . Keywords: anthracene; cation; dimerization; radical; reactivity; Introduction Organic radicals have garnered significant attention in various research fields, including catalysis [1][2][3][4], chromophores [5][6][7][8], and as agents in dynamic nuclear polarization [9][10][11][12]. Recently, highly stable
- the field of radical chemistry. However, reducing the reactivity of radical species can mean losing one of their most attractive properties. Therefore, it is very important to explore aromatic hydrocarbon radicals that are sufficiently stable for handling, yet reactive under specific conditions
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