Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• development of effective receptors for their detection. In particular, the smallest dicarboxylate, oxalate, presents a significant importance due to its widespread presence in nature and its association with various diseases. Yet, very little attention was devoted to the recognition of oxalate with metal

• -driven self-assemblies like cages or containers while numerous classic organic receptors for oxalate exist. This discrepancy is astonishing because metallocontainers or metallocages have advantages over classic macrocycles or organocages like a higher modularity and good preorganization paired with a

• ready receptor preparation by metal complexation. The reason for the underrepresentation is the competitive nature and excellent ligand properties of oxalate which not only is associated with the aforementioned diseases but also poses a serious hazard for metal-driven self-assemblies because the dianion

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• cation of intermediate B is thought to be the magnesium ion, and the magnesium salt of B must be dissolved in the solvent. Although other magnesium salts, such as magnesium carbonate and magnesium oxalate, are also generated during the electrolysis, the magnesium salt of B would be dissolved sufficiently

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• oxalate (9) and alkylphenones 10 through a sterically hindered Claisen condensation, producing a six-membered lithium enolate salt. Subsequent cyclocondensation with hydrazines concludes the formation of pyrazoles. However, this process could not be performed as a one-pot synthesis, as the solvent had to

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• -2H-furan-3-one framework at position C-17 [22]. The one-pot procedure involved the condensation of diethyl oxalate with the α-hydroxy ketone moiety of derivatives 28, immediately followed by a cyclization between the 17α-hydroxy group and the carbonyl group of the α-ketoester in 29. Spiro compounds

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• , and UV light [21], among others. Recent advancements include the photoinduced deoxygenation of acids and alcohols by means of anhydride, xanthate, carboxylate, oxalate, and N-alkoxyphthalimide functionalization (Figure 1) and utilization in visible-light-mediated chemical transformations. Despite the

• excited-state photocatalyst oxidizes the cesium alkyl oxalate via SET, followed by elimination of two carbon dioxide molecules, generating a tertiary alkyl radical that easily combines with an electron-deficient alkene, providing the product. This protocol was well compatible with a wide range of acceptor

• mechanism involves C–O bond activation of tertiary oxalates. It requires [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 and NiCl2⋅DME along with dtbbpy ligand. The reaction commences with single-electron oxidation of cesium oxalate initiated by *[Ir(III)] photocatalyst. This transfer leads to the elimination of two CO2

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• chloride 145. Notably, they observed that no additional chlorine source, such as TsCl, was necessary. Furthermore, they successfully replaced iron oxalate with inexpensive FeCl3 hexahydrate and PhSiH3 with less costly 1,1,3,3-tetramethyldisiloxane. anti-Markovnikov reactions As stated in the introduction

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• late-stage functionalization (17i and 17j) (Figure 12A). Interestingly, sodium oxalate could be used as the electron donor provided a catalytic loading of 4-cyanopyridine was added. Although the role of the latter species was not proposed by authors, it is more facile to reduce than an aryl chloride so

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

• also be used in photochemical reactions, as shown by Gramain et al. in the synthesis of the pyrrolizidine alkaloid (rac)-isoretronecanol (69, Scheme 11) [26]. A Claisen condensation of the lithium enolate of N-acetylpyrrolidine (66) with diethyl oxalate gave the ketoester 67. Irradiation of compound 67

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• for the mode of action of this cascade arylation protocol (Figure 10) [73]. In the photocatalytic cycle, the SET event between the photoexcited iridium catalyst 10-II and the substrate oxalate 33 generates a tertiary carbon-centered radical 10-IV by decarboxylation and the reduced iridium(II

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• (TFE) as a solvent [34][35]. The free amines 13 were converted into stable oxalate salts 14 with quantitative yields. The precipitation reactions proceeded in the presence of 1 equiv of oxalic acid in diethyl ether (Scheme 3) [36]. Unlike amines 13, salts 14 are very stable and can be stored for months

Synthesis and biological evaluation of truncated derivatives of abyssomicin C as antibacterial agents

• Leticia Monjas,
• Peter Fodran,
• Johanna Kollback,
• Carlo Cassani,
• Thomas Olsson,
• Maja Genheden,
• D. G. Joakim Larsson and
• Carl-Johan Wallentin

Beilstein J. Org. Chem. 2019, 15, 1468–1474, doi:10.3762/bjoc.15.147

• intermediates, building blocks 4 and 5 (4, R = Me and 5, R = CH2CH2Ph) were synthesized starting with allyldioxazaborolidine 11, an allyl-transfer reagent that was prepared as previously reported (Scheme 3) [27]. Allylation of methyl pyruvate (12) or 13 (synthesized from dimethyl oxalate and phenethylmagnesium

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• was followed by the addition of diethyl oxalate to give a mixture of compounds including the ketoester 34. Then, treatment of this mixture with hydroxylamine allowed the isolation of the target α-hydroximino ester 35 in a 7% overall yield. Two dimensional NMR experiments confirmed the depicted

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• heterocycle at position 4 is installed by Suzuki coupling with iodide 3a that is synthesized in three steps from ethyl aryl oxalate 4a. The α-ketoester side chain at position 3 was installed by selective halogen-metal exchange of iodide 5a with isopropylmagnesium chloride lithium chloride complex followed by

• quenching with ethyl chlorooxolate furnishing ethyl oxalate 4a in 29–79% yield [12]. This sequence works well with the unsubstituted benzene ring of the series a compounds where R = H. However, to access quinoline 2 with scaffolds such as 4b with halogen substitution in the benzene ring at the 5-, 6-, 7- or

• with diethyl oxalate and sodium ethoxide in ethanol [28]. Isatoic anhydride 9f was then added to the solid enolate and both were dissolved in DMA and warmed to 60 °C for 12 hours. Following the general work-up protocol as described for Scheme 4, a light tan solid was isolated in modest yield after

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• , the iron oxalate–sodium borohydride system, introduced by Boger and co-workers [8], is the only reagent combination shown to accommodate a broad range of SOMOphiles. However, the cobalt–salen complexes that are commonly employed [10][11][13][15][16][30][31][32][36][37][48] contain many different

Coordination-driven self-assembly vs dynamic covalent chemistry: versatile methods for the synthesis of molecular metallarectangles

• Li-Li Ma,
• Jia-Qin Han,
• Wei-Guo Jia and
• Ying-Feng Han

Beilstein J. Org. Chem. 2018, 14, 2027–2034, doi:10.3762/bjoc.14.178

• group. The geometries of the metallarectangles 3a and 3b were expected to be similar, as they comprise two oxalate-bridged half-sandwich rhodium fragments linked by two Schiff-base ligands L1 or L2, giving the desired tetranuclear metallarectangles. In order to test the possibility of using dynamic

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• spectroscopy to determine the nature of the formed products and identified carbonate and oxalate as the main products in addition to traces of glycolate and CO. By comparing the ratio of the integrated band intensities for oxalate and carbonate they concluded that C–C bond scission is influenced by the cation

• oxalate (1310 cm−1) [15][16]. Glycerate and glycolate are presumably also present. Both contain one fully oxidized terminal C atom and by cleaving the C–C bond in glycerate, glycolate can be obtained. Thus, the easiest differentiation would be by a ν(C–O) band at around 1125 cm−1 [15]. This band is not

• or glyoxylate that are only found at higher potentials as intermediate species towards oxalate [13]. The product assignment clearly indicates that increasing potentials favor C–C bond cleavage. Bond scission is likely to proceed via highly oxidized C3 species that are prone to undergo C–C scission

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• situ XRPD monitoring of the formation of glycinium oxalate salts from γ-glycine and oxalic acid dihydrate [42]. Other examples of explorations of the effect of milling frequency on mechanochemical reactivity include aromatic substitution reactions [43] and the synthesis of nitrogen-doped titania [44

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• salts, acetate (Table 1, entry 3) and oxalate (Table 1, entry 4), provided superior yields compared with their inorganic counterpart, sulfate and chloride. The reductive amination reactions were herein conducted at pH 11. Although typical reductive aminations are conducted under acidic conditions, the

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• -hydroxymuconate (3b) [11]. These reactions combine the ethyl 2-halocrotonate with diethyl oxalate followed by alkaline hydrolysis and acidification. Subsequently, the 4Z-isomers of 5-bromo- and 5-fluoro-2-hydroxy-2,4-pentadienoates (5c and 5d) were synthesized enzymatically (following the protocol for the 5

• ice bath and diethyl oxalate (1 equiv, 6.5 g and 4.3 g for 3c and 3d, respectively) was added, followed by the addition of ethyl 2-bromo- or ethyl 2-fluorocrotonate [1 equiv, 6.7 g (42.4 mmol) and 4.4 g (27.9 mmol) for 3c and 3d, respectively]. The ethyl 2-halocrotonates consisted of an E/Z mixture

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• have recently found application as coalescent for paints (Figure 2) [11][12][13][14]. The isosorbide moiety has also been incorporated in several bio-based polymers, i.e., poly(ethylene-co-isosorbide)terephthalate (PEIT), poly(isosorbide oxalate) and poly(isosorbide carbonate) [15][16][17][18] such as

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• to facilitate work-up, recycling, and purification of products, especially for large-scale preparations. These heterogeneous systems include supported metal oxides and binary oxide mixtures. For example, MoO3/SiO2 and sol–gel MoO3/TiO2 is used for the preparation of diphenyl oxalate monomer (DPO

• carbonates obtained through transesterification using phosphonium salts as catalysts. The transesterification of diethyl oxalate (DEO) with phenol catalyzed by MoO3/SiO2. Transesterification of a triglyceride (TG) with DMC for biodiesel production using KOH as the base catalyst. Top: Green methylation of

Total synthesis of leopolic acid A, a natural 2,3-pyrrolidinedione with antimicrobial activity

• Atul A. Dhavan,
• Rahul D. Kaduskar,
• Loana Musso,
• Leonardo Scaglioni,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2016, 12, 1624–1628, doi:10.3762/bjoc.12.159

• A straightforward route to the intriguing 2,3-pyrrolidinedione system appeared to be the Michael addition of a suitable amine to ethyl acrylate, followed by a Dieckmann cyclization with diethyl oxalate [10][11]. We chose the p-methoxybenzyl (PMB) protecting group for the amine, because of its facile

• cleavage with cerium ammonium nitrate (CAN) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). Thus, 2,3-pyrrolidinedione 3 was obtained by the reaction of ethyl acrylate with p-methoxybenzylamine, followed by treatment with diethyl oxalate (Scheme 1) [12]. On the basis of NMR data, the compound exists as an

• leopolic acid A. Reagents and conditions: a) p-methoxybenzylamine, EtOH, rt, 12 h, 98%; b) diethyl oxalate, NaOEt, EtOH, reflux, 3 h, 83%; c) BnBr, K2CO3, DMF, 0 °C to rt, 1 h, 50%; d) DIBAL-H, CH2Cl2, −78 °C, 2 h, 56%; e) PPh3, CBr4, CH2Cl2, rt, 5 h, 52%; f) PPh3, toluene, reflux, 5 h, 75%; g) n-nonanal

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• studied compounds. Results and Discussion Claisen condensation of biphenyl ketone 6 and monomer 2 with diethyl oxalate was carried out in the presence of a base to give β-diketo ethyl esters 8 and 4 in good yields (Scheme 1). All compounds prepared were solid and stable in air. Trans-configuration was

• solution of potassium tert-butoxide (1.75 g, 15.6 mmol) in tetrahydrofuran (20 mL) was added dropwise a solution of dehydrozingerone (2, 1 g, 5.2 mmol) in THF (15 mL) at room temperature under N2 atmosphere. The reaction mixture was stirred at room temperature for 10 min. Diethyl oxalate (1.1 mL, 7.8 mmol

• -hydroxy-4-oxohexa-2,5-dienoate) (8) To a solution of sodium ethoxide (1.1 g, 15.7 mmol) in tetrahydrofuran (20 mL) was added dropwise a solution of 6 (1 g, 2.6 mmol) in THF (15 mL) at room temperature under an N2 atmosphere. The reaction mixture was stirred at room temperature for 10 min. Diethyl oxalate

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• an iodine mediated aromatisation, followed by high temperature mono-methylation using dimethyl carbonate/dimethylimidazole as a more benign alternative to methyl iodide at scale. The subsequent Claisen condensation step between ketone 112 and diethyl oxalate (113) was reportedly hampered by product

Radical-mediated dehydrative preparation of cyclic imides using (NH₄)₂S₂O₈–DMSO: application to the synthesis of vernakalant

• Dnyaneshwar N. Garad,
• Subhash D. Tanpure and
• Santosh B. Mhaske

Beilstein J. Org. Chem. 2015, 11, 1008–1016, doi:10.3762/bjoc.11.113

• dehydrating reagent for imide synthesis [27]. Several dehydrating conditions such as heating in ionic liquid at 140 °C, heating at 150–180 °C under microwave in various solvents, reaction with N,N'-disuccinimidyl oxalate followed by heating in trichloroethylene with 4-(dimethylamino)pyridine, Nb2O5