Electrochemical synthesis of cyclic biaryl λ³-bromanes from 2,2’-dibromobiphenyls

• Andrejs Savkins and
• Igors Sokolovs

Beilstein J. Org. Chem. 2025, 21, 451–457, doi:10.3762/bjoc.21.32

• starts with a single-electron oxidation of 4a on the electrode surface to form cation radical A, in which Br(II) is chelation-stabilized by the carboxyl group [21] and the neighbouring Br substituent [24]. Intermediate A rapidly undergoes irreversible chemical reaction by HFIP coordination to transient

Intramolecular C–H arylation of pyridine derivatives with a palladium catalyst for the synthesis of multiply fused heteroaromatic compounds

• Yuki Nakanishi,
• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2024, 20, 3256–3262, doi:10.3762/bjoc.20.269

• ][7] are found in a variety of advanced materials [8][9] and biologically important molecules [10][11][12]. A wide range of pyridine derivatives have been employed as extractants of metal ions through chelation [13]. Phenanthrolines, a class of pyridine derivatives, have attracted attention for the

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• chelation interaction between the enolate derived from acyclic 1,3-dicarbonyl compounds and copper (Scheme 5, 8a–j). Detailed control experiments indicate that the terminal alkyne moiety is critical and the reaction proceeds through an SN1 mechanism. An outer-sphere nucleophilic attack through copper

• yne-allylic cation intermediate, followed by an intramolecular cyclization. The disparity in reactivity could stem from the chelation between acyclic 1,3-dicarbonyl enolates and the copper catalyst, enhancing γ-position attack in an intramolecular manner. Conversely, Meldrum's acid's rigid cyclic

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• commercially available derivative of ʟ-proline, (S)-(−)-α,α-bis(3,5-dimethylphenyl)-2-pyrrolidinemethanol (62) (Scheme 12). This catalyst is capable of asymmetric activation of N-(2-hydroxyphenyl)imines through the reversible chelation to the N-(2-hydroxyphenyl) group, forming a rigid intermediate, while the

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• -carboxylate (6) and the use of density functional theory (DFT) to evaluate their mechanisms. Over thirty N1- and N2-alkylated products were isolated in over 90% yield regardless of the conditions. DFT calculations suggest a chelation mechanism produces the N1-substituted products when cesium is present and

• the presence of Cs2CO3. To explore the possibility of N2-selectivity, we hypothesized that the phosphine intermediate of a Mitsunobu reaction could provide chelation control, directing alkylation to the indazole N2-atom while using identical alcohols as described above. Thus, we subjected 6 to simple

• the chelation pathway proposed in Figure 5, we hypothesized that 18 (Figure 9) would provide a model for exploring the mechanism further. If chelation between an electron-rich oxygen atom from a substituent and a Lewis acid (such as Cs+ or P+) were taking place, we would expect regioselectivity for

Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA

• Yu Fan,
• Ahmed El Rhaz,
• Stéphane Maisonneuve,
• Emilie Gillon,
• Maha Fatthalla,
• Franck Le Bideau,
• Guillaume Laurent,
• Samir Messaoudi,
• Anne Imberty and
• Juan Xie

Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132

• increasingly limited for treatment of infections. PA has been classified as a priority 1 pathogen by the WHO [2][3]. Various approaches to treating PA, in addition to traditional antibiotics, have been developed including inhibition of quorum sensing, biofilm formation, iron chelation, and interfering with

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• coordinated to the zinc atom: this offers a gain in enthalpy associated to the formation of zinc enolates stabilized by chelation and increases the spin density delocalized at the oxygen atom involved in the chelate. Note that the reported 1,4-additions of dialkylzinc reagents to alkylidenemalonates could

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• amide derived from 8-aminoquinoline 13e (Scheme 6, 13 examples, up to 75% yield). In this study, two mechanisms were reported. The first one suggested that a palladacycle C is formed after the irreversible chelation of the 2-phenylpyridine substrate with palladium, which is the rate-determining step

• were obtained in 30% and 20% yields, respectively. Several mechanistic experiments revealed that the C(sp2)–H bond activation step was reversible and represented the rate-determining step (KIE = 2.4). First, the chelation of the palladium(II) catalyst with the bidentate directing group, followed by the

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

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

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• following example of styrene diamination by a chiral aryl iodide, the higher efficiency of the proposed catalyst compared to simpler aryl iodides was attributed to the additional stabilization of the I(III) intermediate by chelation via n–σ* interactions and hydrogen bonding [147] (Scheme 33). The

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• interesting class of compounds and examples of their use can be found in a number of different areas, including pharmaceuticals [1][2][3][4][5][6], metal chelation [7][8][9], anti-corrosion coatings [10][11][12], fertilizers [13][14], proton conduction [15][16][17], and catalysis [18], amongst others

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• stabilization of reactive conformations by chelation or dipole control. Keywords: aldol addition; ketoesters; natural products; total synthesis; Introduction Vicinal ketoesters contain a carbonyl group adjacent to an ester group. One keto group results in α-ketoesters 1 and two vicinal keto groups lead to α,β

• bearing an electrophilic keto group as reactive site. The vicinal arrangement of carbonyl groups allows the stabilization of reactive conformations by chelation or dipole control. Suitable key reactions are e.g., aldol additions, carbonyl ene reactions, Mannich reactions, and additions of organometallic

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• electron-withdrawing groups inactivates the iridium catalyst, perhaps by chelation with the carbonyl and the bridging oxygen atom. Computational Computational details All density functional theory (DFT) calculations in this study were carried out with the Gaussian 16, C.01 suite of programs [68]. Geometry

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• reactions, and pericyclic reactions. Yoshida and co-workers [100] demonstrated that some metal ions are capable of activating aromatic compounds by chelation and promoting nucleophilic additions. For instance, 1-aminoanthraquinone quickly reacts with butylamine under the influence of Lewis acid catalysts to

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• -dipolar cycloaddition [16][21][22], were submitted to the reaction with benzoyl isothiocyanate in refluxing acetonitrile to obtain compounds L1, L2 and L3 in good yields [16][21]. Due to the very low biological activity of these ligands by themselves, the chelation with nickel(II) and palladium(II) was

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• -stereoselective epoxidation of 2,3-dihydroisoxazole with in situ-generated DMDO, the syn-selective α-chelation-controlled addition of vinyl-MgBr/CeCl3 to the isoxazolidine-4,5-diol intermediate, and the substrate-directed epoxidation of the terminal double bond of the corresponding γ-amino-α,β-diol with aqueous

• -stereoselective epoxidation of 2,3-dihydroisoxazole 9 with in situ-generated DMDO, the syn-selective α-chelation-controlled addition of vinylmagnesium bromide to isoxazolidine-4,5-diol 3 in the presence of cerium chloride, and the substrate-directed epoxidation of the terminal double bond of N-Cbz-protected γ

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• effective enantiopure synthesis of lamivudine (1) were achieved by many scientists. The synthesis of 1,3-oxathiolane nucleosides utilizing stereoselective coupling of a nucleobase with the oxathiolane sugar intermediate via in situ chelation was reported by Liotta and co-workers (Scheme 29) [72

• ]. Appropriate Lewis acids form a complex with the oxathiolane intermediates via in situ chelation. The exclusive formation of the β-anomer was observed upon coupling of the anomer mixture 8 with silylated cytosine using stannic chloride (about 2 equiv in CH2Cl2 at room temperature). This stereoselective outcome

• could have been due to an in situ chelation process. The level of selectivity was determined by HPLC to be >300:1 in favor of the β-configured cis-isomers (racemic mixture of 80a and 80b) [30]. Further, the desilylation using tetrabutylammonium fluoride (TBAF) gave racemic (±)-BCH-189 (1c). Chu et al

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• observed selectivities in metathesis reactions, H-bonding interactions between chloride ligands as H-bond acceptors and OH or NH functions in the metathesis intermediate appear to be determining [35][36]. Selectivity derived from chelation is considered to be an another important contributor. Through the

• formation of intermediates with stable (e.g., six-membered) chelate ring systems, the chelation ability of oxygen functionalities to ruthenium during metathesis can greatly influence the outcome of the CM reaction [36][37]. Steric factors are another important phenomenon, which will possibly contribute to

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• cation chelation via the N-2 atom electron lone pair and the C-3 substituent X=O functionality, respectively [24]. Tight ion pair formation with the sodium cation and both the N-2 atom and C-3 substituents of the indazole scaffold likely hinders the approach of the electrophile to N-2 and directs

• was carried out, using 1 equivalent of the ether 15-crown-5 (with respect to NaH) (Table 5). Chelation of the sodium cation with the crown ether should disrupt the formation of tight ion pairs (Scheme 2) and attenuate N-1 regioselectivity. The presence of 15-crown-5 caused a notable reduction in N-1

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• tryptophan-containing peptides (Scheme 13). A wide variety of complex peptides was explored, affording glycosylated conjugates with high stereoselectivity. The free NH functional group was tolerated in the manganese catalysis protocol, suggesting that the chemoselectivity was controlled by chelation of the

• 31n, regarded as a potentially viable peptide-based biosensor. Manganese-catalyzed inter- and intramolecular C–H alkenylations Manganese(I)-catalyzed C–H alkenylation of 2-phenylpyridines or N-pyridinylindoles with alkynes is characterized by proximity-induced C–H activation through chelation

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• intramolecular hydroamination in the presence of base. Conclusion In conclusion, we have reported on the chelation-assisted oxidative copper-promoted cascade C−H alkynylation and intramolecular annulation. The removable N-2-pyridylhydrazide was utilized to facilitate copper(II)-promoted C−H activations. Thus

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• addition of the chiral auxiliary. Our attention then turned to the stereoselective reduction of 8. Chelation-controlled reduction of 8 using ZnCl2 and DIBALH allowed for the successful formation of 16 as a single diastereomer (Scheme 4), as evidenced by 1H NMR spectroscopy [18]. TBS deprotection furnished

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• of 1,2-aminoalcohol 110 (90% yield, anti/syn 7:3, 78% ee). At the end of the Henry reaction an in-line plug of silica gel removes the catalyst before the second reduction step to prevent issues of chelation and palladium deactivation. Knoevenagel condensations are also of considerable interest to the

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• to the electrophilic iminic carbon took place in a quite rigid system, with chelation of the Lewis acid with the nitrogen of the imine and carboxylate oxygen, forming a five-membered ring. The migration of the vinyl group occurred to the Re face of the imine, which is less shielded than the Si face