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Search for "ligands" in Full Text gives 894 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Total synthesis of grayanane natural products
Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181
- to be tackled. A highly enantioselective synthesis is still desirable, as the only synthesis offering >90% ee relies on the combination of chiral ligands and chiral auxiliary. Moreover, to date only 6 natural products from the grayanane family were synthesized, out of the more than 160 compounds
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
- ) itself failed to catalyze the cycloisomerization (Table 1, entry 1). Evaluation of a number of silver salts illustrated that silver hexafluoroantimonate (AgSbF6) was the optimal additive to activate the gold catalyst (Table 1, entries 2, 3, and 7). Screening of the other ligands of Au(I) catalysts
New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling
Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161
- the same region occupied by crystallographic ligands in their complex with IMPDH. The results obtained in this study suggest that compound 8 might be a new anti-RSV candidate. Keywords: antiviral; betulinic acid; bioisosterism; respiratory syncytial virus; triterpene; ursolic acid; Introduction
- relied on a comparison of compound 8 with crystallographic ligands of IMPDH, on the basis that it would represent a secure interpretation of the site interactions similarity with inhibitors, thus, suggesting that this compound acts by the same mechanism. Therein, flexible docking for compound 8 to the
- IMPDH protein from Mycobacterium tuberculosis (PDB code 4ZQP) was performed. After 10 docking runs, a top-ranked solution was identified and definitively located at the same region occupied by IMP and inhibitor MAD1, ligands of the crystallographic structure in complex with IMPDH. As can be seen in
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
- accompanied by 27% yield of 1,2-dihydroquinoline 4aa (Table 1, entry 1). Then, several other cyclometalated iridium complexes were studied. The catalysts TC-2 and TC-4 containing electron-donating ligands provided quinoline 3aa in higher chemoselectivity and yield (Table 1, entries 2 and 4). On the contrary
- , the catalysts TC-3 and TC-5 containing electron-withdrawing ligands offered lower chemoselectivity and yield (Table 1, entries 3 and 5). Further catalyst screening revealed that TC-6 (6-methoxy) is the best catalyst for the ADC reaction affording the product in a yield of 95% (Table 1, entry 6). On
Comparison of crystal structure and DFT calculations of triferrocenyl trithiophosphite’s conformance
Beilstein J. Org. Chem. 2022, 18, 1499–1504, doi:10.3762/bjoc.18.157
- ensembles from ferrocene-containing ligands and metal ions or clusters. This makes it possible to realize an almost infinite number of multiferrocene compounds and to select leading compounds for the successful creation of molecular electronic devices. It should be noted that with the exception of tertiary
- [7]. It is important to know the conformational capabilities of such ligands for construction of such complexes [8][9][10][11]. However, to date, XRD data on phosphorus derivatives containing a ferrocenyl substituent at the sulfur atom are presented only in oxidized and sulfurized forms
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
- relative binding constants for multiple ligands for a receptor can potentially be determined in the same experiment. However, there are applications of microelectrode arrays that require stable, tunable, and chemically inert surfaces on the electrodes. The use of those surfaces dictate the use of indirect
- amplification and how the problem could be remedied. Amplifications of surface-based signals are typically caused by the presence of multiple ligands for the receptor above any given electrode. If the protein dissociates from one ligand and then rapidly binds another on the surface of the electrode, then it
- never leaves the surface. The surface does not recover its original conductivity and the experiment shows a binding constant that is greater than either of the individual interactions. Alternatively, the surface-bound substrate could lead to avidity events where more than one of the ligands binds to the
Supramolecular approaches to mediate chemical reactivity
Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152
- in the field of the supramolecular catalysis on the use of discrete heteroleptic metallo-supramolecular complexes as catalysts. The idea of breaking/reducing symmetry has inspired many researchers to study heteroleptic metallo-complexes made up of various ligands. The authors emphasized the
Oxa-Michael-initiated cascade reactions of levoglucosenone
Beilstein J. Org. Chem. 2022, 18, 1457–1462, doi:10.3762/bjoc.18.151
- tetraketones 11 promoted by base (Scheme 2) [25]. The equivalent reaction has not been reported for dihydrolevoglucosenone (Cyrene™) 12, and it was thought that the chiral 1,5-diketone products could be used to construct catalysts or ligands. The aldol/Michael cascade using conditions for the aldol reaction
Dissecting Mechanochemistry III
Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150
- the use of halogenated compounds and include the mechanochemical preparation of isocyanides [10], formylated and acetylated amines [11], and the mechanosynthesis of unsymmetrical salens ligands for preparing metal–salen catalysts [12]. This illustrates the broad applicability of mechanochemical
1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes
Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148
- hydrazone groups. The use of N-TAAD derivatives as potential ligands and receptors was showcased through forming boron chelates and host–guest complexes with water and simple alcohols. Keywords: azaadamantanes; cyclotrimerization; hydrazones; inclusion complexes; molecular recognition; Introduction
- Tripodal molecules are widely used as chelating ligands for transition metal catalysis [1][2][3], sensors for ions and small molecules [4][5], reagents for surface grafting [6], building blocks for the construction of supramolecular structures [7], polycyclic cage molecules [8], and porous materials [9
- 1b) [21][22][23]. In particular, N,N,N-trihydroxy-TAAD derivatives (3O-TAADs) were shown to be chelating ligands for boron [24]. The application of TAAD-boronate complexes was demonstrated by the preparation of conjugates of boronic acids with biomolecules [25][26], COF-like materials [25], and
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
- metals have been explored to optimize the catalytic properties of chiral metal–salens, such as Cr [7], Co [8], Fe [9], Ti [10], Al [11], Y [12], and Mn [13] and investigated with numerous nucleophiles to afford chiral molecules. In addition to the variation of metals, salen ligands have also been studied
Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes
Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139
- objects of growing interest in the fields of coordination chemistry [3][4][5] and asymmetric catalysis [6][7]. Due to the sp2-hybridization of the phosphorus atom, phosphaferrocenes are commonly regarded as phosphorus ligands with weaker σ-donor character than classical tertiary phosphines and stronger π
- -acceptor properties closer to phosphites P(OR)3 [8][9]. Since the P atom in phosphaferrocenes retains an electron lone pair, phosphaferrocenes have been used as P-donor ligands [10][11][12] as well as nucleophilic catalysts [13][14]. Recently, the pentaphosphaferrocene Cp*Fe(η5-P5) has been used as a
- replaced with phosphacyclopentadienyl ligands. Related diphosphacyclobutadiene complexes Fe(η4-P2C2R2)2 were oxidized much more cathodically (negative by 1.7–2.0 V) [46][47], which indicated a significant contribution of the phosphacyclopentadienyl ligands to the iron atomic orbitals. Of course the
B–N/B–H Transborylation: borane-catalysed nitrile hydroboration
Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138
- ]. Traditionally, the reduction of nitriles to primary amines relied on stoichiometric hydride reagents [4]. Current catalytic methods for nitrile reduction, hydrogenation [5][6] or hydroboration [7][8], generally rely on metal catalysts, designer ligands, forcing reaction conditions (such as elevated temperatures
Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups
Beilstein J. Org. Chem. 2022, 18, 1322–1331, doi:10.3762/bjoc.18.137
- option to modulate, inhibit, or stabilize protein–protein interactions (PPI) is the use of specific supramolecular ligands [7][8]. One well-known example of efficient protein binders is the so-called guanidiniocarbonyl-pyrrole (GCP) developed 20 years ago by Schmuck et al. [9]. These compounds are known
- an ideal candidate to be used for protein recognition. In a previous study, GCP containing polycationic ligands for 14-3-3 proteins had a significant effect on PPIs [12][13]. Furthermore, a simple GCP derivative, GCP-Lys-OMe, was identified as the first binder for the specific binding area of the 14
- overcome this issue is to use fluorescence emission as a read-out tool, such as an emission “on” or “off” behavior [15]. Selective and sensitive fluorescent ligands have been proven to be essential tools for the study of biological systems by biosensing and imaging [16]. There is an increasing demand for
Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants
Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135
- system as well as a cysteine thiolate ligand from the protein backbone (Figure 1B). The generally accepted catalytic cycle for hydroxylations is shown in Figure 1C. In the resting state A, the central ferric ion is coordinated by six ligands, four from the porphyrin ring system, one cysteine thiolate
Ferrocenoyl-adenines: substituent effects on regioselective acylation
Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133
- applied to quantify the fraction of the defined sphere around a reaction center [46]. It was introduced for ligands on metals [47], but may be adapted to estimate the steric hindrance of substituents in different chemical environments (see Supporting Information File 1 for more details). As expected
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
Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives
Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121
- , alanine, serine and cysteine derivatives are formed as an antibonding combination of the Ni dx²-y² orbital with the group orbitals of the ligands; the π* orbital of the imine and the π orbital of the phenylene fragments are also partially involved. Reduction occurs at similar potential values and is
A Streptomyces P450 enzyme dimerizes isoflavones from plants
Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113
- challenging and often requires prefunctionalization of the substrate monomers, costly metal ligands, or tedious protection–deprotection steps [6][7][8][9]. With the advance of biosynthetic studies on natural products, a number of enzyme classes that are responsible for the dimer formation have been identified
Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof
Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111
- diversity of metal complexes incorporating 1,2,3-triazoles as ligands have been reported [16][17][18]. Triazole ligands with N-heterocycles such as Pyta (4-(2-pyridyl)-1,2,3-triazole) and related structures were employed to obtain novel metal complexes as catalysts [19][20] and imaging probes [21], as well
- confirmed via single crystal X-ray crystallography. Several other byproducts, such as the bistriazolo product were isolated (see Supporting Information File 1). The obtained triazoloquinoxaline and TIQ products are promising ligands for complexation with different metals. The formation of organometallic
- complexes is a well-established method to obtain interesting materials for catalysis [31][32][33] and optoelectronics [34][35], as well as for biological applications [36][37]. Therefore, the obtained triazole and TIQ products were employed to act as ligands in rhenium tricarbonyl complexes. These are
Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones
Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110
- '-dimethylethanolamine (DMEA) and trans-1,2-diaminocyclohexane (DACH) were evaluated as ligands (Table 1, entries 18 and 19). However, the yield was lower compared to that obtained with 1,10-phenanthroline (phen). Control experiments were performed without catalyst (Table 1, entry 20), base (Table 1, entry 21), or
Electrochemical formal homocoupling of sec-alcohols
Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108
- ]. Such scaffolds are widely utilized as versatile building blocks in the synthesis of biologically active compounds [3][4][5][6][7], chiral auxiliaries [8][9], and chiral ligands [10][11][12][13]. Traditional pinacol coupling reactions are performed with a stoichiometric or even excess amount of low
First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell
Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98
- as ligands in organometallic catalysts [9] and as versatile organocatalysts [10] in a very wide range of organic reactions such as classical benzoin condensation, transesterification, acylation, Knoevenagel reaction, Claisen condensation etc. The electrochemical generation of carbenes from ILs avoids
Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides
Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90
- )aminoalkanoic acids 86 (Scheme 15) [35][36]. This is a convenient way to synthesize γ-phosphonolactams 85. They further extended their method to synthesize cyclic O,O- and O,S-bidentate ligands with a P–N–P backbone. The substitution reaction of 3-bromopropylamine hydrogen bromide (87) and chloroethoxyphosphine
Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry
Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86
- various phosphine ligands [62] for this reaction (Table 1, entries 1–8). Interestingly, we found that tri-tert-butylphosphonium tetrafluoroborate (t-Bu3P·HBF4) provided the borylation product 3a in excellent yield (92%, Table 1, entry 1), with a small amount of the protonation product 4a (5%, entry 1
- 3). Reactions with DPEphos and XPhos, which are the optimal ligands for neat liquid conditions reported by Nechaev [15], also yielded only poor results (Table 1, entries 4 and 5). Other monophosphine ligands, such as SPhos, PCy3, and PAd3, did not improve the yield of 3a (Table 1, entries 6–8). The
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