Search results
Search for "ligand" in Full Text gives 967 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer
Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98
- )phosphine ligand (PN3P) (Mn3) and studied N-methylation reactions in the presence of t-BuOK (20 mol %) at 120 °C for 24 h in toluene [36]. This catalytic system tolerated various functional groups, including nitro, ester, amide, and ketones and gave moderate to good yields (42–98%) of the mono-N-methylated
- condenses with hydrazine followed by reduction and condensation with another aldehyde to afford the N-substituted hydrazones (Scheme 8). Balaraman and co-workers established a phosphine-free manganese catalyst generated in situ from a manganese precursor and a ligand for the N-alkylation of anilines with
- ). However, N-methylation of anilines with methanol required 100 °C to yield the selective N-methylated products. The same year, Hultzsch et al. designed PN3-pincer ligand-supported Mn(I) complexes for the alkylation of amines with primary and secondary alcohols [42]. Most interestingly, a low catalyst
Novel analogues of a nonnucleoside SARS-CoV-2 RdRp inhibitor as potential antivirotics
Beilstein J. Org. Chem. 2024, 20, 1029–1036, doi:10.3762/bjoc.20.91
- of HeE1-2Tyr (1), it must be considered that the synthesized ligands were significantly smaller in size. Normalization of the obtained results using the binding efficiency index (BEI) [32] suggest that both ligand types, 3a–c and 4a,b, bind more efficiently to the SARS-CoV-2 RdRp when compared to 1
Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions
Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90
- . This method allows for the hybridization of complex bioactive and fluorescent-labeled carboxylic acids with diaryliodonium(III) salts. Keywords: auxiliary ligand; diaryliodonium(III) salts; hybridization; hypervalent iodine; organocarboxylates; Introduction Hypervalent iodine compounds are an
- -arylation using aryl(2,4,6-trimethoxyphenyl)iodonium(III) acetates [13]. In this process, the acetate ligand acted as a base to activate the phenol group and positioned it in proximity to accomplish the smooth SNAr reaction. The synthesis of diaryliodonium(III) salts with various counterions, such as
- reported [18][19] (Scheme 1). The importance of the trimethoxyphenyl (TMP) group as an auxiliary (dummy) ligand on the iodonium salt has prompted researchers to synthesize aryl(TMP)iodonium(III) trifluoroacetates via oxidation of iodoarene with m-chloroperbenzoic acid (mCPBA) in the presence of
Carbonylative synthesis and functionalization of indoles
Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87
- protocol the use of a Lewis base such as SnCl2 was not required and the reaction took place under milder conditions using Pd(OAc)2 as catalyst and PPh3 as ligand. The reaction was performed at 70 °C for 15–48 hours, under 4 bar of CO in a DMF/MeOH 2:1 mixture giving the indole derivatives without obvious
- second case the reactions were catalyzed by 6 mol % of Pd(OAc)2 and carried out under 4 bar of CO. The fused indoles were obtained when adding 24 mol % of dppp (1,3-bis(diphenylphosphino)propane) at 120 °C for 70 hours in DMF. Instead, in the other case, PPh3 was used as ligand at 70 °C for 17–46 hours
- as ligand, because it was already known that catalysts derived from palladium(II) salts and bidentate nitrogen ligands were highly reactive systems for the reduction of o-nitrostyrenes [28][29][30]. The catalytic system Pd(OAc)2/1,10-phen worked better than Söderberg´s one (Pd(OAc)2/PPh3) under mild
Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles
Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84
- herein an enantioselective palladium-catalyzed Heck–Matsuda reaction for the desymmetrization of N-protected 2,5-dihydro-1H-pyrroles with aryldiazonium salts, using the chiral N,N-ligand (S)-PyraBox. This strategy has allowed straightforward access to a diversity of 4-aryl-γ-lactams via Heck arylation
- -lactam ring is a privileged scaffold widely present in drugs and natural products [12][13][14], as shown in Scheme 1. Herein, we report the effective desymmetrization strategy of N-protected 2,5-dihydro-1H-pyrroles using aryldiazonium salts and the chiral N,N-ligand (S)-PyraBox (Scheme 2). The obtained
- the palladium source in combination with the pyrazinebisoxazoline ligand, (S)-PyraBox (L1), zinc carbonate as base, and methanol as solvent at 40 °C. These initial conditions furnished 2-methoxypyrrolidines arylated at the 4-position, compound 3, as Heck products as illustrated in Scheme 3. The
Monitoring carbohydrate 3D structure quality with the Privateer database
Beilstein J. Org. Chem. 2024, 20, 931–939, doi:10.3762/bjoc.20.83
- validation report is the beginning of the carbohydrate information, listed as ‘glycans’ in the JSON format. Within this ‘glycan’ scope, information is segmented into glycan types, that is, ‘n-glycan’, ‘o-glycan’, ‘s-glycan’, ‘c-glycan’, and 'ligand'. Each of these glycan types contains an array of individual
One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline
Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81
- both gave cyclized product 6a in 70% yield (Table 1, entries 3 and 4). An increase of the reaction time to 12 h did not improve the yield (Table 1, entry 5). The reaction was further evaluated in the absence of ligand which afforded the product in 35% yield (Table 1, entry 6). Screening of ligands, e.g
Synthesis and properties of 6-alkynyl-5-aryluracils
Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80
- low yield of the first approach. Replacing the catalyst and increasing the temperature or the amount of boronic acid proved to be unsuccessful. With entry 6 (Table 1) it was shown that similar yields could be obtained by removing the ligand and using higher amounts of catalyst. Therefore, no
- additional ligand was used in the next attempts. Additionally, it was observed that by replacing the less polar solvent by a mixture of a more polar solvent and water in a 5:1 ratio, yields could be significantly improved. Therefore, sodium hydroxide was used as the water-soluble base, which also proved to
(Bio)isosteres of ortho- and meta-substituted benzenes
Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78
- benzenes that have more than one substituent; for example, the ortho-, meta-, or para- relative substitution of a disubstituted benzene should ideally be replicated in the saturated bioisostere to ensure ligand–protein binding is conserved through the bioisosteric swap. Bioisosteres of para-substituted
Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria
Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75
- (Scheme 1) [20][21]. Vs NnlA contains a Per-Arnt-Sim (PAS) domain – protein domains that often bind heme and function as gas or redox sensors [20]. Indeed, Vs NnlA was shown to contain a heme cofactor [21]. Mutagenesis of a predicted histidine ligand to this heme resulted in loss of the heme and the
- [32]. We sought to identify the heme binding site, but AlphaFold does not model this. However, this AlphaFold model was predicted to bind a heme cofactor by the consensus modeling tool COACH [33]. This protein–ligand model exhibited steric clashes with the heme and protein side chains (data not shown
- ), limiting the use of this model to predict the heme environment. Nevertheless, this protein–ligand model heme binding between the β-sheet and an α-helix based on similarity to the oxygen-sensing dimeric DosH protein [34]. DosH is also a heme-binding PAS-domain containing protein, further validating the
Advancements in hydrochlorination of alkenes
Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72
- and 3 in Table 7). The reaction with only oxidized ligand (dppeO2) also works indicating that structure 103 could also be the active hydrochlorination complex (compare entries 4 and 5 in Table 7). The applicability of the reaction is confined to highly reactive 1,1-disubstituted or trisubstituted
- functional tolerance of this methodology is striking. Especially examples with sensitive aldehyde (175), nitrile (176), N-Boc (177), furan (178), thiophene (179), and even tertiary alcohols (180 and 181) are impressive. The primary drawback of this methodology lies in the synthesis of the ligand L3
Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives
Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62
- depends on the relative configuration of the ligand used; cis-configuration of ligand affords the nitroaldols with major enantiomer S- (up to 97% ee), whereas the application of ligands with trans-configuration led to nitroaldols with major R-enantiomer (up to 96% ee). The “proline-type” ligand IV was
- ; Introduction The application of chiral metal complexes as enantioselective catalysts is among the fundamental strategies for preparing compounds in non-racemic forms [1][2][3][4]. These complexes typically comprise a chelating chiral ligand capable of coordinating with a metal ion; otherwise, a metal atom
- itself constitutes a stereocentre [4]. The specific pairing of a chiral ligand and a metal ion is essential for the catalytic characteristics and its effectiveness of the complex in asymmetric syntheses [1][2][3]. In recent years, our research group has synthesised a series of chiral ligands based on 2
Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines
Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59
- started our studies with the palladium-catalyzed MCR of ethyl diazoacetate (1a), 1,3-butadiene (2a), and 1-phenylpiperazine (3a) in the presence of 5 mol % Pd(OAc)2 and 10 mol % Xantphos as ligand. To our delight, after irradiation with blue LED light in dimethylformamide (DMF) for 12 h at room
- experiments indicated that ligand, palladium, light and argon atmosphere were necessary for this transformation (Table 1, entries 2–5). Heating conditions could not facilitate the reaction instead of light conditions (Table 1, entry 6). The efficiency was maintained with another Pd(II) catalyst Pd(PPh3)2Cl2
- of the hybrid α-ester alkylpalladium radical generated from the diazo ester (Table 1, entry 10) [53]. Replacing Xantphos with rac-BINAP or DPEphos gave very low product formation, indicating that the type of ligand was crucial for this transformation (Table 1, entries 11 and 12). Changing the
A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts
Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54
- -step ynamide annulation and imidazolium ring-formation sequence. Metalation with Au(I), Cu(I) and Ir(I) at the C2 position provides an L-shaped NHC ligand scaffold that has been validated in gold-catalysed alkyne hydration and arylative cyclisation reactions. Keywords: annulation; carbene; gold
- secondary gold-ligand interactions [8][9][10], chiral environments [11][12][13] including those enabling secondary interactions with substrates for asymmetric catalysis [14], cooperative and bimetallic catalysis [7][15], and redox-enabling function for Au(I)/(III) cycles [16][17]. Such L-shaped ligands
- provide scope to influence the reactivity profile of their resulting metal complexes through steric shielding, direct stabilising interactions with the metal, or by proximal effects to reactive species. Given the sensitivity of metal catalysis to even subtle steric and electronic changes in the ligand
Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides
Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48
- treatment of acute severe pain) [29] and an investigational drug NOP-1A (a ligand for the nociceptin/orphanin FQ peptide (NOP) receptor which is thought to be involved in several central nervous system disorders such as anxiety, depression, drug abuse, and seizures) [30]. A wide range of biological
- properties are exhibited by compounds based on a THF and THP core spiro-conjugated with the pyrrolidine ring. These frameworks are present in a number of synthetic biologically active compounds (such as NaV1.7 blocker XEN907 for the treatment of pain [31], σ1 receptor ligand 6 [32], histamine-3 receptor
Switchable molecular tweezers: design and applications
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
- particularly evident for metal complexes, where the system's geometry can be finely tuned to modulate its response based on the selection of metal and ligand components. This aspect has been extensively explored by Schmittel and co-workers in a recent review [17]. Molecular tweezers have been developed in this
- -workers introduced a switchable system based on a terpyridine (terpy) ligand (Figure 8), which is structurally similar to the diphenylpyridine units used by Zimmerman in rigid clips, but can change their conformation upon complexation by a metal cation [32][33]. When substituted at the 6 and 6" positions
- system and enable dynamic ligand formation due to the reversibility of the hydrazone bond formation [40]. More recently, Vives and co-workers have developed a family of terpyridine-based tweezers bearing metal–salphen complexes as functional units (Figure 9). Using metal complexes as arms brings
Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination
Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43
- out under a variety of conditions with cationic gold catalysts supported by phosphine ligands. The impact of ligand on gold, protecting group on nitrogen, and solvent and additive on reaction rates was determined. The most effective reactions utilized more Lewis basic ureas, and more electron
- both within the context of a classic gold π-activation/protodeauration mechanism and a general acid-catalyzed mechanism without intermediate gold alkyls. Keywords: alkene hydroamination; general acid catalysis; gold catalysis; isotope effect; phosphine ligand effect; solvent effect; Introduction
- undertaking a 1H NMR spectroscopic kinetic survey of solvent, ligand, and substituent effects on the general reaction 1 → 3 (with a variety of N-protecting groups), to supplement known qualitative observations. We found that, (1) electron-withdrawing phosphines accelerate hydroamination, (2) reactions are
Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells
Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39
- previously described an activity-based protein profiling (ABPP) strategy for NRPSs using ABPs that target A-domains (Figure 2b) [13][14][15]. The probes comprise an aminoacyl-AMS ligand and a photoaffinity group with clickable alkyne functionality appended to the 2′-OH group of adenosine. A complex structure
- probes (AA-AMS-BPyne) can selectively label the A-domains corresponding to the amino acid of the ligand in both recombinant enzymes and proteomes. We recently reported that these probes can be used to label the A-domains of endogenous NRPSs in live bacterial cells [17][18][19]. The intracellular labeling
Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives
Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37
- derivatives (Scheme 1b) [21]. In the course of this reaction 20 mol % of Pd catalyst, 50 mol % of phosphine ligand and 30 equiv of DBU as base were used to afford the desired fluoranthene derivatives. 1-Naphthylboronic acid and 1,2-dibromobenzene in the presence of Pd2(dba)3 (20 mol %) and PCy3 (80 mol
Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters
Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35
- [20][21]. More recent approaches have leveraged photoinduced ligand-to-metal charge transfer to generate radicals from aliphatic [22] and aromatic [23][24] carboxylic acids. However, more broadly used approaches involve carefully designed activated esters. Barton esters 2 emerged in the early 1980s
- -halides [115]. Their optimized reaction conditions required a NiII precursor, 2,2’-bipyridine (bpy) as ligand, silver nitrate (AgNO3) as an additive and the combination of a magnesium (Mg) sacrificial anode and a RVC cathode (Scheme 35A). A crucial discovery in advancing this methodology was the in situ
Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin
Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31
- binding in solution and a further confirmation of the binding specificity obtained by the array experiments. We note that the functional activity of bacterially produced CMA1 indicates that potential modification by glycosylation is not required for ligand binding. Next, we set out to quantify the binding
- arrangement of the ligand in the binding site (Figure 4c,d). While lectins such as CMA1 typically can present three binding pockets in their CBM13 domain, we hypothesized that the N-terminal half of CMA1 would in fact only exhibit two functional binding sites. However, only the alpha site was found occupied
- (BioRad). 0.6 mg/mL protein in PBS was mixed with SYPRO Orange (Sigma-Aldrich, Merck, #S5692) and glycan ligand (10 mM GalNAc; Carbosynth, #MA04390; 10 mM GlcNAc, Carbosynth, #MA00834; 10 mM blood group H type-2 tetrasaccharide; Elicityl, GLY032-2) in a total reaction volume of 25 µL. The temperature was
Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C70 production
Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28
- group was substituted by a mesyl substituent and BIPHEP was used as a model phosphine ligand instead of Tol-BINAP to reduce the computational cost. The calculations, conducted at the B3LYP-D3/cc-pVTZ-PP(SMD=o-DCB)//B3LYP-D3/cc-pVDZ-PP level (see full computational details in Supporting Information File
Catalytic multi-step domino and one-pot reactions
Beilstein J. Org. Chem. 2024, 20, 254–256, doi:10.3762/bjoc.20.25
- ; multi-step reactions; multicomponent reactions; one-pot synthesis; organocatalysis; tandem reactions; transition-metal-catalysis; The synthesis of pharmaceutical ingredients, natural products, agrochemicals, ligand systems, and building blocks for materials science has reached a high level of
Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs
Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19
- (entry 1, Table 1). Next, the same procedure was carried out in the presence of molybdenum hexacarbonyl (Mo(CO)6, 2 equiv) as CO surrogate, under the previous conditions, but again we only observed the formation of intermediate 3a in 21% yield (entry 2, Table 1). Changing the ligand to triphenylphosphine
- effective ligand in a variety of highly efficient aminocarbonylation reactions with Mo(CO)6 due to its strong basicity and accelerated release of CO from this reagent [21]. The reaction was then screened using two different bidentate ligands, XPhos and XantPhos, and using the previous reaction conditions
- -step synthesis of DBDAPs, we embarked on an in-depth study of the B–H coupling/carbonylative cyclization in a step-wise fashion. Our first attempt was conducted using the previous conditions, which led to the desired compound 3a in 15% yield (entry 1, Table 2). Changing the ligand to PPh3 under the
Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes
Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13
- wormlike nanoparticles. In rotaxanes, the utilization of metal–ligand bonding involving CuI is a common strategy for immobilizing a thread moiety within a macrocycle. However, the efficacy of such a bonding is compromised when catalysts are used in stoppering reactions, e.g., the copper-catalyzed azide
- –alkyne cycloaddition reaction. Consequently, a [2 + 2] CA–RE reaction that can yield push–pull chromophores without the use of a catalyst is exceedingly valuable as a stoppering method, even for systems featuring metal–ligand bonding. Accordingly, Diederich et al. demonstrated the synthesis of a CuI bis
- room-temperature solution (dichloromethane) and as a frozen matrix at 77 K [123]. This is in contrast with the typical homoleptic phenanthroline-based CuI complexes renowned for their emissions from a triplet metal-to-ligand charge transfer excited state. The absence of luminescence may be attributed
Other Beilstein-Institut Open Science Activities
