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

• carboxylate-assisted C−H cleavage to deliver copper(II) intermediate A. Next, the copper(III) carboxylate species B is generated. Thereafter, a facile base-assisted ligand exchange is followed by reductive elimination to afford the alkynylated benzamide D. Finally, the desired isoindolone 3 is formed via an

• 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

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• and aromatic amines. Being free amines aliphatic amines reacted better with arylcyanoguanidine in the presence of excess copper(II) salts in aqueous ethanol, whereas aniline derivatives were more prompt to react as hydrochloride salts in a suitable high boiling point solvent. The reaction with copper

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• an easy pathway to synthesize such triazolylenones. Inspired by this result, we proceeded to optimize the reaction conditions to further improve the yield. Replacement of rhodium by copper (II) acetate slowed down the reaction with a marginal change in the yield of the product 3a (Table 1, entry 2

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• the coordination of copper(II) through nitrogen atoms of the pyridin-2-yl substituent, the pyridazin-3-one moiety, and the 2-(dimethylamino)ethyl group. In the vis–NIR spectrum recorded in methanol, based on TD-DFT calculations, the d–d, metal–ligand charge transfer (MLCT), ligand–metal charge

• compound moiety. Based on the results of X-ray structural analysis of the Cu(II) complex with 7, it can be assumed, that also in the case of ligand 5i (L2) the nitrogen atoms of the pyridin-2-yl and azomethin moiety participate in the coordination with Cu(II) ions. Crystallography of complex 17 The copper

• (II) complex 17 [(L3)Cu(II)Cl2] was synthesized and characterized by X-ray analysis, FTIR and vis–NIR spectroscopy (for details see Supporting Information File 2). The molecular structure of the complex 17 is shown in Figure 4 and Figure 5. The basic experimental details and selected crystallographic

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• to prepare α-thiocarbonyl compounds. In this way, Bolm and collaborators elaborated a copper(II) acetate-catalyzed reaction of β-dicarbonyl compounds with diaryl disulfides (Scheme 1A) [50]. In 2017, Zou and co-workers described the preparation of α-thiocarbonyl compounds through a reaction of 1,3

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• anion concentration [31]. Similar effects were achieved by using a tripodal copper(II) complex as the external crosslinker [32][33]. Finally, the metal ion-induced aggregation of AuNPs containing DPA residues in chloroform or acetonitrile/water was reversed by the addition of diphosphate anions (which

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• -2,3,4,6-tetraacetylglucose (1.48 g, 3.96 mmol), copper(II) sulfate pentahydrate (52 mg, 0.21 mmol), and sodium ascorbate (28 mg, 0.14 mmol) in tetrahydrofuran/water cosolvent 2:1 (10 mL, v/v) was stirred vigorously under nitrogen in the dark at 60 °C for 24 h. Then, the solvent was removed under reduced

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• the catalyst SiO2@H3PW12O40 [21], the reaction of tetracarbonyl compounds with o-aminothiophenol (1a) [22][23], the reaction of copper(II) chelate of ethyl pentafluorobenzoylpyruvate with o-aminothiophenol (1a, one example) [24] and the reaction of DMAD with 6-nitro-1,3-benzothiazole (one example) [25

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• , base, and temperature on the course of the CEL arylation in the presence of copper(II) acetate monohydrate (Table 1). As observed for dichloromethane medium, the reaction proceeded very efficiently, with a product 3a yield of 88%, and reached completion within 48 h upon the addition of 2 equiv of

• replacement of pyridine by other organic bases/ligands (4-DMAP, 2,2’-bipy, Et3N, TMEDA, 8-hydroxyquinoline) resulted in poorer yields of the target product in all cases (Table 1, entries 6–10). The use of copper(II) fluoride (in contrast to triflate) instead of acetate had practically no effect on the

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• Cu(ClO4)2 afforded a better yield of the C–O coupling product 48 then the manganese-based oxidants in this case (Scheme 17) [94]. A radical mechanism was suggested. The copper(II) ion reacts with oxime 19 to generate iminoxyl radical 20 and also forms complex 49 with dinitrile 47. Interaction of

• -position (R1, R2 = Me), as well as oximes having a disubstituted double bond, also give cyclization products with good yields (products 152b,c). The interaction of β,γ-unsaturated oximes 153 with sodium sulfinates in the presence of copper(II) acetate leads to substituted isoxazolines 154 with the sulfonyl

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• (purchased from Aldrich), 9H-carbazole, copper(II) chloride (purchased from Reakhim), and 2,7-di-tert-butyl-9,9-dimethyl-9,10-dihydroacridine (purchased from Center for Physical Sciences and Technology) were used as received. Thin-layer chromatography was performed using TLC plates covered with silica gel

• solid sample of compound 1 (e, inset). Synthesis of quinazoline derivatives 1–3. Conditions: i) ammonium acetate, copper(II) chloride, isopropanol, reflux, 24 h; ii) donor moiety (D), NaH, DMF, reflux, 24 h. Electrochemical characteristics. Photophysical properties of compound 1–3. Funding This project

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• % ee (22c, Scheme 7A) [31]. The research group of Alexakis was able to push this chemistry further when they developed a new methodology that allowed to access the chiral lactams 26 with moderate yield and high enantioselectivity (up to 96% ee). Therein, the copper(II) naphthenate/L5-catalysed ACA of

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• another family of galactose oxidase mimics based on copper(II) complex 4 bearing a non-innocent iminophenol-iminopyridine hybrid ligand 3 that performed two-electron oxidations of primary alcohols to aldehydes (Scheme 2) [15]. Catalyst 4 was fully characterized by combined EPR, cyclic voltammetry and

• study of a new copper(II) complex. A family of o-phenylenediamido ligands was synthesized through the introduction of ureanyl groups, using a synthetic approach developed by Borovik [17][18] for the stabilization of metal–oxo and metal–hydroxo complexes via intramolecular H-bonding interactions. The

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• oxidized to Cu(II) species. Without using a ligand or a reducing agent, Cu(II) can oxidize alkynes to produce an undesired byproduct. Active copper catalysts can be prepared by reducing copper(II) sources, oxidizing copper metal, comproportionation of Cu(II) and Cu(0), or combination of copper salts and

• ). The ICP analysis of 45 revealed a strong attachment of the copper species to the functionalized nanosilica. Furthermore, the composite 45 demonstrated good catalytic activity in five consecutive cycles. Recently, the synthesis and catalytic application of a copper(II)–2-imino-1,2-diphenylethan-1-ol

• triazole products, excellent reusability, short reaction times, and good to high yields. Further, Dufauda et al. reported a copper(II)–phenanthroline complex supported on the SBA-15 architecture, Cu(II)phen@SBA-15 (58) [31]. The preparation is outlined in Scheme 9: Initially, phen-functionalized mesoporous

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• . Mechanistically, the authors proposed that an electron transfer took place between the copper(I) complex and ICF2CO2Et, forming, after iodine transfer, a new carbon-centered radical and a copper(II) complex. The center of the radical then shifted to the terminal carbon atom of the unsaturated compound. The latter

• reacted with the copper(II) complex, forming a new copper(III) intermediate. After reductive elimination, the desired difunctionalized compounds were formed. Tetramethylammonium trifluoromethylselenolate salt (Me4NSeCF3) Tetramethylammonium trifluoromethylselenolate was reported by the group of Tyrra in

• compatible with aromatic as well as aliphatic substrates and tolerated sensitive functional groups, such as hydroxy functions or esters (Scheme 12). Boronic acids were also engaged in combination with ClSeCF3 in the presence of stoichiometric amounts of copper(II) acetate, resulting in marginal to moderate

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• , Mauduit, Campagne, and co-workers set up a highly enantioselective 1,4-addition of dimethylzinc to a wide scope of α,β-unsaturated acylimidazoles 35 [38]. Among the various ligands screened in combination with copper(II) triflate, the hydroxyalkyl-chelating NHC precursor L14 proved to be the most

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• the hydroxymethyl group in 10 to furnish 11 in 82% yield. After having obtained the 2,7-anhydrosialic acid derivatives 5–11, they were subjected to various Lewis acid-catalyzed ring-opening reactions. In line with this, Sc(OTf)3-, copper(II) triflate-, and SnCl4-catalyzed acetolysis of diacetylamino

Iodine-mediated hydration of alkynes on keto-functionalized scaffolds: mechanistic insight and the regiospecific hydration of internal alkynes

• Zachary Lee,
• Brandon R. Jones,
• Nyochembeng Nkengbeza,
• Michael Phillips,
• Kayla Valentine,
• Alexis Stewart,
• Brandon Sellers,
• Nicholas Shuber and
• Karelle S. Aiken

Beilstein J. Org. Chem. 2019, 15, 2747–2752, doi:10.3762/bjoc.15.265

• extremely harmful to environmental and biological systems [3]. In light of mercury’s toxicity, the synthetic community has given much attention to the use of less harmful reagents. Success has been obtained with many other transition metal salts, for example, palladium(II) [4][5], rhodium(III) [6], copper

• (II) [7], silver(I) [8], and gold(I)/(III) [9][10][11][12]. While less toxic than mercury, such catalysts are still environmental hazards and tend to be costlier [13][14]. The iodine-mediated hydration described herein is a viable solution to these issues [15][16]. This metal-free method produces

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• observation than cyanine-based fluorophores [24]. Different synthetic approaches were established to form the silicon rhodamine framework 1 (Scheme 1). While the group of Wu used a copper(II) bromide-catalyzed solvent-free condensation of a diarylsilane 2 with various benzaldehydes 3 [25], Sparr and Fischer

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

• Gerardo M. Ojeda,
• Prabhat Ranjan,
• Pavel Fedoseev,
• Lisandra Amable,
• Upendra K. Sharma,
• Daniel G. Rivera and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

• the relatively cheap complex (p-cymene)ruthenium(II) chloride dimer, in the presence of copper(II) acetate as oxidant under conventional heating. Despite all effort put in this attempt, the isolated yields were in the range of 14–62%, with the highest yield achieved after 24 h of reaction using 10 mol

• optimization varying the solvent (Table 1, entries 1–4), the isolated yield of 4a was increased to 90% (Table 1, entry 4) with the use of tert-amyl alcohol (t-AmOH). Other experiments (Table 1, entries 5–7) proved the importance of both cesium acetate and copper(II) acetate for the reaction to proceed

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• copper(II) ions was achieved with IV. Diarylethene V and its analogs were used as chemical sensors for a number of metal ions [27]. Despite of recent advances in this area, the scarcity of reported examples requires the search and design of novel photoswitchable ligands with advanced properties. In this

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• co-workers [71] described the one-pot asymmetric gem-chlorofluorination of active methylene compounds by using a copper(II) complex with a chiral spiro 2-pyridyl monooxazoline ligand (SPYMOX). The corresponding α-chloro-α-fluoro-β-keto esters were isolated with up to 92% ee (Scheme 29a). This

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165