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Search for "selectivity" in Full Text gives 1291 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives
Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24
- .19.24 Abstract A synthesis of 1,4-imino-ᴅ-lyxitols and their N-arylalkyl derivatives altered at C-5 is reported. Their inhibitory activity and selectivity toward four GH38 α-mannosidases (two Golgi types: GMIIb from Drosophila melanogaster and AMAN-2 from Caenorhabditis elegans, and two lysosomal types
- -deoxy-DIM was 3.5 times more potent toward AMAN-2 than DIM, their selectivity profiles were almost the same. N-Arylalkylation of 6-deoxy-DIM resulted only in a partial improvement as the selectivity was enhanced at the expense of potency. Structural and physicochemical properties of the corresponding
- . This explains why potent GMII inhibitors like swainsonine tend to lack significant selectivity. Therefore, the search for potent and selective GMII inhibitors is rather challenging. Over the last decades, almost all attempts at overcoming the selectivity challenge posed by swainsonine have not been
Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series
Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23
- following criteria: position/stage of the key cyclooctane ring formation in the synthesis plan, the selectivity, and the opportunity for late-stage functionalization. Review 1 Metathesis: ring-closing metathesis and related methods The metathesis reaction, first discovered by serendipity in the 1950s, has
An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies
Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19
- ) dimerization has some limitations, such as its controlling selectivity for intermolecular reactions in differently activated alkenes, and low reactivity. Han and co-workers [6] addressed the latter one by designing a substrate in which nucleophile functionality is also present in the Michael acceptor to
Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris
Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16
- synthesis by Taber that used dichromate as an oxidant [13] led to a less diastereoselective reaction furnishing the three ketones 9, 10, and 11 in a ratio of 36:2:5. The cis-conformation of the decalin backbone of 9 and 11 originates from the endo-selectivity of the Diels–Alder reaction and the boat
Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry
Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15
- aromatic Grignard reagents which do not bear ω-magnesium alkoxide functionalities: in that case, EtOMgX can be used as an external additive to enhance the cross-coupling selectivity, in line with the alkyl–alkenyl and aryl–alkenyl cross-coupling methods discussed earlier (Scheme 5) [32]. The beneficial
Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds
Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11
- [14], we had undertaken some preliminary investigations into the use of commercially available Diversinate™ reagents and showed the bicyclic nitrogen-rich core of Series 4 was amenable to this chemistry, with radical sulfinate substitution occurring with high-selectivity at C-8 and in respectable
Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation
Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2
- isolated in 34% yield indicating that steric effects play a role during the oxidation step. We further wanted to investigate different arenes, but due to the lack of selectivity of the primary benzyl acetates in the Friedel–Crafts step, we were limited to para-substituted arenes, which unfortunately all
Combining the best of both worlds: radical-based divergent total synthesis
Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1
- platforms [66], the group considered a system in which a photoexcited catalyst oxidatively cleaves a siloxycyclopropane with endo selectivity [67], leading to aryl–nickel capture and reductive elimination. Thus, when substrates 121 and 122 were photoirradiated with blue LED light at 45 °C in the presence of
- drastically the radical stability, nucleophilicity, and selectivity of 139 [73]. Furnishing of the common scaffold 130 can be carried out via an attack of intermediates of this type (e.g., 139) on Michael acceptors. Tosyl group deprotection of 130, followed by selenium anhydride oxidation and catalytic
- process, two major families of natural compounds are formed, namely the aporphine and the morphinandienone alkaloids. Mimicking the selectivity of the natural process in laboratory setups commonly proves tricky, producing an irreproducible yield of isomers for both classes. Recently, Felpin’s group
Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B
Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185
- IC50 0.96 µM) and 4.85 µM (amphotericin B IC50 4.87 µM), respectively. Furthermore, digyalipopeptide A (1) produced IC50 values of 10.07 µM (ampicillin IC50 0.18 µM) and 10.01 µM (ampicillin IC50 1.53 µM) for Staphylococcus aureus and Shigella sonnei, respectively. The selectivity and toxicity profile
- of compound 1 was investigated using normal cell lines, macrophages RAW 264.7. When tested against normal macrophages, compound 1 gave an IC50 value of 71.32 μM. Selectivity indices (SI) were obtained by calculating the ratio of the IC50 in RAW 264.7 to the IC50 in the respective microbe and
- 10.01, 18.71, and 10.01 µM, respectively. The laboratory standard itself produced IC50 of 1.53 µM for Shigella sonnei, Shigella flexneri 1.76 µM, and Staphylococcus aureus 0.18 µM, respectively (Table 3). The selectivity and toxicity profile of compound 1 was also investigated using normal cell lines
Total synthesis of grayanane natural products
Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181
- selectivity was achieved by chelation of the Sm(III) intermediate with hydroxy groups present on the structure. As the direct coupling with the A-ring precursor failed, a strategy to build this part was developed, starting with a sequence involving a protection of the alcohols as MOM ethers, lactone
- suitable starting material for the SmI2-promoted pinacol coupling, directed by the free hydroxy group, affording a complete selectivity in the formation of the 7-membered ring B. The synthesis of grayanotoxin III was then achieved by acetylation of the secondary alcohols, oxidative cleavage of the MOM
- , obtaining excellent selectivity in all cases. Alternatively, the same year, the authors published a vinyl radical cyclization occurring in presence of n-Bu3SnH, providing a stereoselective access to the bicyclo[3.2.1]octane unit corresponding to the CD rings [25]. Newhouse’s synthesis of principinol D In
Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field
Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179
- oxidative coupling processes (also known as cross-dehydrogenative coupling), as well as late-stage CH-functionalization. Oxidation processes are recognized as a challenge in fine organic synthesis technology [10][11] due to selectivity problems and frequent need for toxic transition metal salts and
- stoichiometric oxidants. The development of organic chemistry is strongly affected by rising “green” demands to synthetic methodologies, including reduction of waste formation, low trace-metal content in drug compounds, high energy-efficiency and selectivity of processes. In the last decade researchers proposed
- that hydrogen bonding is considered as one of the key factors determining the selectivity of catalyst-free sulfoxidations [68]. In such reactions, the selectivity of sulfide oxidation by oxone (sulfoxide/sulfone ratio) was controlled by the solvent nature (deeper oxidation was observed in water than in
Navigating and expanding the roadmap of natural product genome mining tools
Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178
- secondary metabolite biosynthetic enzymes are distant paralogs of enzymes involved in primary metabolism [63][71]. These NP biosynthetic enzymes are hypothesized to have undergone significant sequence and selectivity changes while still operating based on the same reaction mechanism (e.g., fatty acid
A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine
Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172
- alcohol. We build on a commercially available imidazopyridine derivative and conceived a protecting group strategy to enhance solubility and selectivity to orchestrate the installation of the exocyclic amino and hydroxy groups. Results and Discussion 1-Deazaguanine Previously described syntheses for 1
- -1-deazapurine [16], the key reactions are copper-catalyzed benzyl ether formation and site-specific nitration. The application of protecting groups was necessary for reasons of solubility and to improve selectivity. The obtained heterocycles may serve as core compound for further structural
Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy
Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169
- ring smoothly, leading to the exclusive formation of biaryl intermediate 11 in a yield of 82%. It is worth noting that the methoxy substitution in the substrate played a crucial role in controlling the selectivity of the cycloisomerization according to our previous study [15]. It was rationalized that
Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities
Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159
- reactions have the advantages of high atom economy, simple operation, clean and green, and have become a research hotspot [31][32][33][34][35]. Cyclometalated iridium complexes with good catalytic efficiency and selectivity are very effective catalysts in ADC reactions. Moreover, these catalysts are easy to
- secondary alcohols 2 that allowed for the efficient synthesis of a series of quinolines 3 (up to 95% yield and >99:1 selectivity) (Figure 2). A preliminary evaluation of the compounds’ potential antibacterial activity was also performed. Results and Discussion We started our research with the ADC reaction
- the other hand, when no catalyst was added to the reaction system under the above conditions, the reaction also proceeded, but the chemical selectivity and yield were significantly lower (Table 1, entry 7). In order to obtain optimal conditions, the bases, reaction medium, and temperature were also
Microelectrode arrays, electrosynthesis, and the optimization of signaling on an inert, stable surface
Beilstein J. Org. Chem. 2022, 18, 1488–1498, doi:10.3762/bjoc.18.156
- array because it is the nature of those molecules that defines the biological interactions that can be studied [10][11]. As discussed below, such efforts need to not only control the selectivity of the reactions for specific, predetermined sites on the array, but also control the surface concentration
- complex molecule, the synthesis of a complex, two-dimensional addressable surface requires a new type of selectivity – "site-selectivity". The use of electrosynthesis is essential for obtaining this selectivity. With the substrate on the surface of the array, a hydroquinone/quinone redox couple was then
Supramolecular approaches to mediate chemical reactivity
Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152
- substrate(s) and potentially the transition state is essential in supramolecular catalysis. Supramolecular catalysis finds inspiration in natural enzymes, which show catalytic features such as substrates and products selectivity, efficiency, geometric control, and acceleration of chemical reactivity [1]. If
- catalysts were designed that showed substrate selectivity, turnover, regioselectivity, and stereoselectivity [5][6][7][8][9][10][11][12][13][14]. Supramolecular architectures with an internal cavity are potential candidates to work as supramolecular catalysts [5][6][7][8][9][10][11][12][13][14]. The first
- whose geometry, in low-polarity solvents, is controlled by the 1,2,3-alternate conformation of the calix[6]arene skeleton. These catalysts can tune the selectivity of the catalytic cycloisomerization of 1,6-enynes in response to the relative orientation of the coordinated gold(I) atom with respect to
Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides
Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147
- -aryloxy alcohols were thereafter synthesized through the KR of epichlorohydrin with different phenols using chiral Co–salen catalyst 2f (Table 3). meta-Substituted methylphenol showed less reactivity and selectivity (Table 3, entry 2), while tert-butyl monosubstitution at the para-position on the phenol
On drug discovery against infectious diseases and academic medicinal chemistry contributions
Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141
- chances of being identified in the course of screenings. In 2004, the Molecular Library Initiative sponsored by the NIH also tried to address such issues and provide probes to determine the function and therapeutic potential of all the human genes. Aside from considerations on the selectivity and drug
Polymer and small molecule mechanochemistry: closer than ever
Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128
- that are different from those found in solution. Computational studies have been a key to understand the role of mechanical force in such reactions and to explain the changes in selectivity under force [42][43][44]. For example, experimental results have demonstrated that ball milling in a planetary
From amines to (form)amides: a simple and successful mechanochemical approach
Beilstein J. Org. Chem. 2022, 18, 1210–1216, doi:10.3762/bjoc.18.126
- . Under these experimental conditions, we did not detect the formation of the sulfonamide derivative, preserving complete selectivity towards the target formamide (Table 2, entry 4). Remarkably, the results remain unchanged regarding yields and purity by shortening the reaction time (Table 2, entry 5
Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates
Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124
- (BINAP)-assisted hydrogenation with H2 pressure up to 50 bar was also found to be ineffective. By changing the metal complex to Rh(COD)2BF4, we successfully realized the saturation of the double bond. Chiral ligands (R)-BINAP (L1) and (R,R)-phenyl-BPE (L4) gave unsatisfactory selectivity (Table 2
Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones
Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118
- proposed based on computational results and the main product is formed favorably following the PES via the lowest ΔG# pathway in both the gas-phase and an ethanol solvent model. DFT calculations showed that kinetic selectivity is more significant than thermodynamic selectivity for forming main products
- IS5, in good agreement with the experimental results. Besides, the kinetic selectivity is more significant than the thermodynamic one for forming the main product 10ab with a rate constant ≈ 103–106 times higher (from the first step to the final step) in ethanol solvent (also in chloroform, DMSO) as
Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor
Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115
- complexated catalyst (Ni@poly-czbpy). Based on previous batch optimizations we aimed for a ligand/metal ratio of 2:1 to ensure no unligated nickel is present as it negatively impacts the selectivity. By recirculating a solution of NiCl2∙glyme (4.3 mM) through the reactor for three hours (flow rate: 0.5 mL/min
A Streptomyces P450 enzyme dimerizes isoflavones from plants
Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113
- reactions (Figure S1, Supporting Information File 1). Due to the high reaction selectivity that the enzyme active site offers, these enzymes provide biocatalytic means for the biaryl linkage formation, and recent enzyme engineering efforts also demonstrated selective and efficient production of unnatural
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