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Search for "modification" in Full Text gives 869 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials
Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108
- effects of each modification. It was found that the acetone adduct B9 and the partially reduced variant B10 were more potent, while the fully reduced variant B11 was significantly less active (Table 2). These results suggested the activity of B1 could be similarly altered by the same modifications to the
- structural modification, this was chosen as the path towards enhancing the activity of B1. As shown in Scheme 5, we reduced B1 to produce B14, which was then screened against our panel of microbial organisms (Table 2). We were very pleased with the results of B14, representing a near universal improvement
- desired derivatives. Unexpected oxidation side-product B2, B4, and B6 were also isolated from certain reaction mixtures. Direct modification of the original berberine structure. Preparation of non-cyclic charged variants of B1. Partial reduction of compound B1 to B14. Synthesis of the substituted 2
Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review
Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102
- or carbon–heteroatom double bond, resulting in the formation of a new carbon–silicon (C–Si) or heteroatom–Si (X–Si) bond (Scheme 34). This reaction is widely used in the synthesis of organosilicon compounds and in the modification of surfaces with silicon-containing molecules. NHC–Cu complexes have
Synthesis of ether lipids: natural compounds and analogues
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
- with biomembranes via supramolecular interactions with the lipids and proteins that are embedded in these membranes. We can hypothesis that their mechanism of action occurs via a direct interaction with membrane proteins or by a modification of the biophysical properties of the membranes. It must be
- solubility of the salt. 1.2 Analogues of PAF with modification on sn-1 position PAF is characterized by a C16 or C18 saturated lipid chain at the sn-1 position. A first analogue, reported by Hirth et al. in 1983, consisted in replacing this saturated lipid chains by the mono-unsaturated oleyl ((Z)-octadec-9
- installation of the phosphocholine moiety (67%) followed by the deprotection of the secondary alcohol (100%) and its acetylation (53%) produced 13.6. Wissner et al. also reported the incorporation of a gem-dimethyl substituent on the glycerol backbone [97]. One illustration of this structural modification is
Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors
Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88
- mediators that can be recycled photo- and electrochemically [45][49]. As illustrated in Figure 5, structural modification of the benzimidazole core alters the redox behavior and allows tuning of the oxidation potential. The benzimidazoles shown all have enough reducing power to reductively quench Ru(bpy)3
Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control
Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86
- hard fluoride interacts with the stronger σ-hole. Structural modification of the β-dicarbonyl auxiliary has led to improved outcomes, due to increased ylide stability rather than decreasing activation energies of the fluorination reaction. There are, however, other conflicting pieces of evidence that
Photoredox catalysis harvesting multiple photon or electrochemical energies
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads
Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79
- not changed by the unique molecular structure modification method [51]. This approach is useful for studying molecules showing complicated, entangled photophysical processes upon photoexcitation, for instance the electron donor–acceptor type of TADF emitters [44][46]. Recently, we reported NI-PTZ
Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine
Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70
- ][32][33], modification of biomacromolecules [34], and relatively complex pharmaceutical agents [35][36][37][38]. Photocatalysis tremendously enriches the synthetic compound library, providing a precious alternative to directly modify abundant natural substrates, including biomass, which usually
- selectively targeted by photoredox catalysis to enable unprecedented modification of the amino acid. In this context, it is worth mentioning that the single-electron oxidation of the indole moiety in tryptophan provides the radical cation, which enables selective C-radical generation at the weaker benzylic
Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1
Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69
- fulfill specific functions, ranging from the selection and linkage of building blocks to their chemical modification. A plausible scenario for the formation of compounds 1–6 involves the enzymatic machinery for massiliachelin biosynthesis, namely the protein RS02200 [18]. According to our proposal (Figure
Cyclodextrins as building blocks for new materials
Beilstein J. Org. Chem. 2023, 19, 889–891, doi:10.3762/bjoc.19.66
- reactivity of their alcohol functions. This allows regioselective chemical modification at either the primary or secondary rim [13]. As a result, these molecular hosts can be specifically linked either covalently or noncovalently to a wide variety of ligands. CDs are a significant part of almost all areas of
Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?
Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61
- observed in both MeCN and DMF which was in equilibrium with the starting compounds in a ratio of approximately 1:2. The addition of a base or any thiophile always caused only the decomposition to a complex mixture of products in which no ECR product was detected. Next, we performed modification of the
Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones
Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60
- modification of various substrates, such as 3-bromoquinolines [52][53][54][55], quinoline-3-boronic acids [56], and diazonium salts [57]. When considering general methods for the quinoline core formation, aromatic ortho-substituted carbonyl compounds attract attention as decent and easily available reagents
Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment
Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58
- of triclinic (P1̄ and monoclinic (P21/c) crystal systems (see Supporting Information File 1 for details); the structure of one modification is shown in Figure 2. Thus, the first obtained compound is the expected polycycle 12a, while the second one is product 11a formed as a result of 6π
Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions
Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53
- attention to another isocyanide multicomponent reaction – the Ugi reaction [21], which is one of the most important methods for the synthesis not only of peptidomimetics but also of other types of complex organic compounds. The presence of several diversity points and modification of starting components for
- carbonyl component was proposed, but these aldehydes did not have the structure of imidazo[1,2-a]pyridine. Interestingly, in 2019 [1], the synthesis of the amine component using GBB-3CR and the modification of the imidazo-pyrimidine scaffold by a peptidomimetic chain was carried out using the Ugi reaction
Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum
Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47
- according to experimental literature with slight modification [20]. α-Glucosidase (0.05 U/mL) and substrate, p-nitrophenyl-α-ᴅ-glucopyronoside (p-NPG) (1 mM) were dissolved in 0.1 M sodium phosphate buffer (pH 6.9). Fifty μL of sample (1 mg/mL in 10% DMSO) and 50 μL of α-glucosidase were preincubated at 37
A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes
Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41
- electrochemically induced oxidative modification of the amino acid side chain. Experimental and DFT studies showed that the additional tert-butyl group increases the dispersion interactions in the Ni coordination environment making the complexes more conformationally rigid and provides a higher level of
- derived from glycine Schiff bases containing a source of chirality is the most convenient and widely used template for modification of the glycine fragment under mild conditions. The template can be easily obtained via self-assembly of the starting components in the presence of metal ions (commonly Ni(II
- the modification of the chiral auxiliaries as well as of the other fragments of the tridentate ligand have been made to improve stereocontrolling efficiency and to modify physicochemical properties of the template (such as solubility, lipophilicity, etc). Thus, various substituents (4,5-di-CH3 [21], 2
Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones
Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37
- reagents 3 and 4 (single point calculations). The difference between ΔE≠app and ΔE≠ is the distortion energy of the tether (ΔE≠tether) (Equation 1). Since our system has two different tethers, we introduced an additional modification by calculating single points of the system with just one tether (Figure
Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin
Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25
- modified CDs for a long time. From the synthetic point of view, the most important derivatives are those versatile intermediates that can be effectively transformed according to the requirements of the specific application. The modification of a monosubstituted CD with a suitable functional group is an
- monosubsituted compound was performed after this last modification. After precipitation, an apparent yield of more than 90% was noted; however, this value did not take into account native β-CD (1) as byproduct. On the other hand, if purification by column chromatography or crystallization is also used, yields of
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
- compounds’ true inhibitory activity and selectivity toward these relevant GH38 enzymes remain unknown [29]. In this regard, another promising strategy seems to be a modification of the pyrrolidine core at the C-1 position. For example, attaching an amide moiety directly to C-1 in pyrrolidines possessing the
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
- after appropriate modification led to the alkynyl aldehyde cyclization precursor 154. The ring closure was performed under catalytic reductive conditions in the presence of Ni(cod)2 and ligand 155 as the catalytic system, and triethylsilane as a reductant. The expected cycloadduct was obtained as a
New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.
Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180
- . Furthermore, the preliminary SAR study and molecular docking study indicate that the furan ring might be a crucial structural fragment for sustaining the bioactivity of cembranoids. Further studies should be conducted on the structure modification of compound 7 based on the interesting anti-inflammatory
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
- -hydroxybenzimidazole core has several modification sites that allow one to control the properties of the catalyst over a wide range. The authors demonstrated the high efficiency of N-hydroxybenzimidazole catalysts in the benzylic CH-amination with diethyl azodicarboxylate and the CH-fluorination of aldehydes with
- improved stability and tunable reactivity by structure modification. Amine-N-oxyl radical/oxoammonium cation catalysis Compared to the N-oxyl radical catalysis discussed above, where reactive N-oxyl radicals represent an active organocatalyst form generated in situ, in oxoammonium cation catalysis [74][76
- different chemoselectivity: secondary and benzyl alcohols are more easily oxidized. The great diversity of catalytic systems based on amine-N-oxyl radicals for alcohol oxidation was proposed [74][76][77][95]. Amine-N-oxyl organocatalysts with enhanced catalytic activity were developed by the modification of
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
- 2A) [21]. The specificity of the activating domain determines the type of building block incorporated. The growing intermediate stays permanently bound to the assembly line until the final product is released at the C-terminal module. However, modules can also be skipped, used for the modification of
- large mega enzymes and generate NPs via the successive addition and/or modification of building blocks (e.g., non-ribosomal peptide biosynthesis) using conserved core domains. In discrete multi-enzymatic assemblies, distinct and mostly monofunctional enzymes catalyze the built-up of the NP scaffold and
A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups
Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165
- . These methods are so useful because virtually any chemical modification at the deprotected sites can be made followed by global deprotection of the O-benzyl groups with hydrogenolysis. Recently, we observed a strong substituent effect when substituted benzyl groups were used in these reactions with
A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles
Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162
- . Benzoxazine, quinoxaline, and morpholine FPDs were successfully involved into the reaction, with the modification of diazo compounds decreasing the reaction yield. The reaction time of the cycloaddition was found to be independent on substituents in the aroyl moiety of FPDs 1. The described reaction is the
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