Search results
Search for "function" in Full Text gives 1112 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures
Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81
- photocyclization reaction sites of 5 were predicted by the orbital-weighted Fukui function in Multiwfn using Gaussian 09 [31][32] at the B3LYP/6-31G** [33] level of theory to verify the reaction-site selectivity of oxidative photocyclization further. Results showed that the conformations of 5a are varied, but the
- orbital-weighted Fukui function is not connected to conformation. In the orbital-weighted Fukui function, the larger the isosurface distribution, the higher the activity of reactions. Thus the 4 and 6-positions of benzene are the most likely sites for reaction (see Supporting Information File 1, Figure
Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity
Beilstein J. Org. Chem. 2022, 18, 722–731, doi:10.3762/bjoc.18.72
- , calculated mass of 31.9 kDa) (Figure 2) caught our attention due to its low sequence identity on the amino acid sequence level (coverage below 50%) with other characterized Ptases. To further explore the putative function of UbiA-297, we generated a phylogenetic tree using 444 Ptase sequences with already
- tyrosine (Tyr-56) residue, which likely fulfills a similar coordinative function. Furthermore, a conserved arginine residue (UbiA-297 R145) was detectable, which was located in the neighboring α-helix (R145) and in proximity to the binding motif, and was hypothesized to be involved in the coordination
- enzymatic activity. We then tested, if heterologously produced UbiA-297 homologs from A. machipongonensis PR1 and Z. uliginosa DSM 2061 (Figure 6D) perform similarly, and indeed observed farnesylation of 8-HQA for both enzymes, which indicated again towards a conserved function of UbiA-297 enzymes within
Structural basis for endoperoxide-forming oxygenases
Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71
- endoperoxidase, NvfI shares a low amino acid sequence similarity with FtmOx1 (only 17%) and a phylogenetic analysis indicated that it is located in a different clade from FtmOx1. Prior to the structure–function analysis of NvfI, four pathways were proposed for the formation of fumigatonoid A from asnovolin A
Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis
Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62
- advantages of utilizing self-assembly to construct discrete nanocages with predetermined geometry and function is the use of a one-pot reaction employing complementary organic linkers with inorganic metal ions. Although the one-pot synthesis of homoleptic metallacages has been thoroughly investigated over
Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid
Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59
- 2018a using the trapz function. The given values for τ do not account for the porosity of the packed bed. They are calculated via Equation 1 with V as the volume of the empty reactor and as the volumetric flow rate. Kinetics To investigate the influence of pressure on the selected reaction, a
- : 1.6 MPa at 2 mL/min, 54 MPa and 110 MPa at 1.8 mL/min, reactor volume: 0.21 mL, 10 mM potassium phosphate buffer 7.50, 1 mM ATP, 1 mM MgCl2, 55 mg particles loaded with epimerase. Measured reaction rate of the immobilized epimerase as a function of pyruvate and pressure. Dashed lines are fitted to a
Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold
Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55
- other hand, their specific geometry enables intriguing transformations with simultaneous involvement of the diazo function and the benzylidene fragment. DAS were first described in 2020 and were involved in a [2 + 1] cycloaddition to aldehydes to give oxiranes [1]. Later on, we developed a convenient
Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions
Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51
- Hao Guo Yu-Fei Ao De-Xian Wang Qi-Qiang Wang Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China University of Chinese Academy of Sciences, Beijing 100049, China
Amamistatins isolated from Nocardia altamirensis
Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40
- , H-35), and 7.83 ppm (dd, J = 7.9, 1.7 Hz, H-36). The upfield-shifted resonances of H-33 and H-35 suggested an electron-donating substituent at C-32 and the chemical shift of the latter (δC 158.1 ppm) supported the assignment of a hydroxy function in this position. From an analysis of the chemical
- next to the ε-amino group in the lysine moiety. The assumption of a hydroxylamine function is consistent with tandem MS data, which showed mass shifts of 16 Da in the corresponding region in comparison to compound 3. Compound 5 (0.7 mg) was obtained as a clear oil. Its molecular formula of C36H53N5O10
- function. Due to the similarity of both molecules, we propose that compound 6 possesses the same absolute configuration as pseudomonin A. The affinities of compound 1–6 for the coordination of ferric iron were evaluated with the CAS assay [9] and compared with EDTA [13]. While the half-maximal displacement
A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions
Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38
- sixty hydrogen bonds between six units of 1 and eight water molecules (Scheme 1). A very recent publication investigated different possible assemblies that are present in solution as function of the water content [22]. The pseudo-spherical host structure is highly dynamic, with a large cavity of about
- presence of electron-rich aromatic surfaces. In a recent publication, Reek [22] further investigated the self-assembly properties of 1 as function of the content of water in chloroform-d demonstrating that the symmetrical hexameric capsule 16·(H2O)8 comprising 8 water molecules (capsule A) is present only
Site-selective reactions mediated by molecular containers
Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35
- function of molecular containers to override natural reactivity and produce unusual site-selective products. Intriguingly, upon irradiation, a site- and stereoselective [2 + 2]-photoaddition between 2 and 7 took place smoothly, giving rise to the syn isomer of the 5,6-adduct 9. In a following work, the
Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates
Beilstein J. Org. Chem. 2022, 18, 217–224, doi:10.3762/bjoc.18.25
- nitroso aldol reactions as a practical tool for the selective introduction of amino or hydroxy moieties at the α-position of a carbonyl function [27][28][29][30]. The last two decades have witnessed an upsurge of interest in the development of organocatalyzed nitroso aldol reactions in addition to the
Diametric calix[6]arene-based phosphine gold(I) cavitands
Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21
- polarity solvents, of a novel class of diametric phosphine gold(I) cavitands characterized by a 1,2,3-alternate geometry. Preliminary catalytic studies were performed on a model cycloisomerization of 1,6-enynes as a function of the relative orientation of the bonded gold(I) nuclei with respect to the
- cycloisomerization of 1,6-enynes as a function of the relative orientation of the bonded gold(I) nuclei with respect to the macrocycle. Further studies are currently under progress to outline the role of the macrocycle and to verify if a possible re-orientation of the gold(I) nuclei towards the center of the
Synthesis and late stage modifications of Cyl derivatives
Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19
- digest and metabolic processes [3]. Furthermore, cyclization generally helps to fix the active conformation of a peptide needed to interact with the respective cellular target. Incorporation of non-proteinogenic and unusual amino acids often is related to their biological function. For example, trapoxin
Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions
Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14
- in the literature, which generally involve four components. These include one primary amine, two multiple bonds, and one aldehyde function [27]. However, one advantage of our study is that we only used three components since the cinnamaldehyde derivatives 3 played the role of two components at the
- to the more stable aldehyde form C. In the second step, the nitrogen atom of the enamine function attacks the aldehyde carbon atom of the cinnamaldehyde unit in 3, and one water molecule is eliminated to give the desired product. Both steps are accelerated by the presence of the catalyst. In support
Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides
Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13
- on reactions believed to involve a direct interaction with the substrate, or with a species (such as a cation) directly formed from the substrate. Sulfonyl chlorides were included in several early considerations of the reaction rates, for processes involving organic substrates, as a function of
Peptide stapling by late-stage Suzuki–Miyaura cross-coupling
Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1
- part in the destruction complex for β-catenin labelling in the canonical Wnt signalling. Loss-of-function mutations in this pathway lead to a dysregulated signal transduction causing cancer [75][76]. All-hydrocarbon stapled peptides comprising amino acids 467 to 481 of the axin CBD had been studied in
A photochemical C=C cleavage process: toward access to backbone N-formyl peptides
Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202
- Haopei Wang Zachary T. Ball Department of Chemistry, Rice University, Houston TX, USA 10.3762/bjoc.17.202 Abstract Photo-responsive modifications and photo-uncaging concepts are useful for spatiotemporal control of peptides structure and function. While side chain photo-responsive modifications
- calculated from crude 1H NMR using residual CD3OD peaks as internal standard. (a) Photocleavage of compound 6 under acidic conditions. Yields determined by 1H NMR using residual CD3OD as an internal standard. (b–d) Selectivity of photocleavage of alkenyl amide 1 as a function of pH. Product percentage of N
Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases
Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191
- imines, Schiff bases have the general organic function -C=N- [2], and are known to have a wide range of biological activities, including antioxidant [3], antitubercular [4], antibacterial [5], antimicrobial [6], and antifungal properties [7], in addition to their role as chemosensors [8] (Figure 1
- attributed to a greater electronic conjugation provided by the imine function present in the molecules of the series 3. Photostability and singlet oxygen quantum yield (ΦΔ) assays In order to be efficient for applications in photobiology, organic dyes must be stable when subjected to light irradiation for
- long periods of time. Thus, the photostability parameter is an important characteristic considering that photogenerated singlet oxygen (1O2) can react with a dye molecule, promoting its degradation [32]. Based on the changes in the UV–vis absorption spectra as a function of time, the Schiff base
Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes
Beilstein J. Org. Chem. 2021, 17, 2773–2780, doi:10.3762/bjoc.17.187
- [3,4-d][1,2,3]triazines and their derivatives, for example, were reported to function as anticancer compounds [28][29][32], herbicides [19][20][21], antimicrobials [18], and pest control agents [35]. Several possibilities have been reported to gain the scaffold of pyrazolo[3,4-d][1,2,3]triazines
GlycoBioinformatics
Beilstein J. Org. Chem. 2021, 17, 2726–2728, doi:10.3762/bjoc.17.184
- for current global health challenges and to understand just about every biological process. Molecular dynamic modeling to understand how glycans interact with biomolecules visualizes and allows the development of hypotheses regarding the function of glycans to be tested at a molecular level. The
The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids
Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183
- (treatment with excess methyllithium) to give the corresponding alkaloids with free N–H function. This dual use of the ethoxycarbonyl group shortens the synthetic routes to hydroxylated 1-benzyltetrahydroisoquinolines significantly. Not surprisingly, these ten alkaloids did not show noteworthy effects on
- ]. This prompted us to investigate the generality of this approach (dual function of the ethoxycarbonyl residue as activating group for the Pictet–Spengler reaction and as protective group for phenolic groups). This effort ended up with short and effective total syntheses of ten racemic 1-benzyl-1,2,3,4
Synthetic strategies toward 1,3-oxathiolane nucleoside analogues
Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182
- -based lactol. This is a necessary requirement to produce the desired stereochemistry in the product. It was extensively reported that the β-selectivity could be due to the formation of an oxonium ion, which is stabilized through anchimeric assistance of the ʟ-menthyl ester function. The method requires
- stereoselective N-glycosylation. We hypothesize that because of the Lewis acid character, ZrCl4 could most likely form a precomplex with the sulfur atom of the oxathiolane ring, as in IV. The presence of the chiral ʟ-menthyl ester auxiliary function assists the complexation with ZrCl4 in a specific orientation
N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts
Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176
- itself, in which the carboxylic function acts as an ancillary hydrogen-bond donor for the direction of one of the reagents [9]. Amines serve as basic units and nucleophilic components capable of carbonyl compounds activation via enamine or iminium ion formation [10][11]. In particular, pyrrolidine became
α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions
Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172
- -moderate yields but with ≥74% ee, while the α-amino ketone products 15 could be obtained in nearly quantitative yields and variable ee, from 53% to 98% [6]. A fifth example of an enantioselective α-ketol rearrangement provides a twist by demonstrating the ability to function on substrates protected as
- use of silica gel and montmorillonite K 10 as catalysts is that they function under neutral conditions, permitting the use of acid-sensitive groups, such as silyl ethers. For example, 101 was converted to 102 in 70% and 96% yield, respectively, with silica gel and montmorillonite K 10, but with
Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing
Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171
- specific pH while using materials compatible with the colon. Also, assessing swelling as a function of NaCl concentration began to explore osmotic interactions of hydrogels, adding to the consideration of environmental conditions and providing data in a region often overlooked in these types of studies. A
- polyamidoamine (PAMAM) dendrimers have been shown to be effective for minimally invasive drug delivery [83]. The reinforced cryogels main function was to provide scaffolding for cell growth and also incorporated the anti-inflammatory corticosteroid drug betamethasone sodium phosphate (BSP) for delivery when
- shows promise to solving these problems and enhancing skin substitutes [7]. An optimal bio-scaffold would have to be biocompatible, biodegradable, have a high pore connectivity and swelling ratio as its function is to promote cell growth and act as a nucleus for cell migration. Moreover, ideally it
Other Beilstein-Institut Open Science Activities
