An azobenzene container showing a definite folding – synthesis and structural investigation

• Abdulselam Adam,
• Saber Mehrparvar and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2019, 15, 1534–1544, doi:10.3762/bjoc.15.156

• ][22]. Beside the usage of the side chains of the amino acids and the azole rings for molecular recognition, the functional groups of the scaffolds of these cyclopeptides have also been applied as receptors for Y-shaped anions [23] and as ligands for copper(II) complexes [24][25]. Of special interest

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• B3LYP and CAMB3LYP functional and 6-31++(d,p) basis-set [56]. Materials Iodine, zinc(II) chloride, copper(II) chloride, potassium hydroxide, chlorotrimethylsilane, copper(I) iodide, and potassium phosphate were purchased from Merck. Diisopropylamine, bis(dibenzylideneacetone)palladium(0

• was stirred at −78 °C for 1.5 hours after complete addition of LDA and then a solution of zinc(II) chloride (1.0 g, 7.3 mmol) dissolved in 5.6 mL dry THF was added. After stirring for one hour at 0 °C, copper(II) chloride (986 mg, 7.3 mmol) was added in one portion and the resulting mixture was

Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• (solution B). Copper(II) chloride (0.02 g, 0.10 mmol, 0.1 equiv) was dissolved in acetonitrile (6 mL) with sonication and cooled to 0 °C (solution C). Once all solutions had been cooled the following order of addition was used: solution C was added to solution A dropwise. Solution B was added dropwise to

• ) then cooled to 0 °C (solution A). tert-Butyl nitrite (0.15 g, 170 μL) was dissolved in DCM (6 mL) and cooled to 0 °C (solution B). Copper(II) chloride (0.02 g, 0.10 mmol, 0.2 equiv), was dissolved in acetonitrile (6 mL) with sonication and cooled to 0 °C (solution C). Once all solutions had been cooled

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• thiophenol was also accomplished using potassium cyclopropyl trifluoroborate. Keywords: aryl cyclopropyl sulfides; copper(II) acetate; copper catalysis; cyclopropylboronic acid; thiophenols; Introduction Aryl cyclopropyl sulfides are present in many biologically active compounds, mainly in their oxidized

• copper(II) triflate and Hünig's base, rearranges to give the corresponding 2-(arylthio)-3-alkyl-1,3-butadiene 10 [12]. Reacting methyl 2-phenylthiocyclopropyl ketone 11 with silyl enol ethers 12 in the presence of dimethylaluminium chloride leads to the functionalized cyclopentanes 13 via a highly

• equivalent of copper(II) acetate, 1.0 equivalent of bipyridine, and 2.0 equivalents of sodium carbonate in dichloroethane at 70 °C for 16 hours provided the desired S-cyclopropylated compound 1a in 86% yield accompanied by only 4% of the diaryl disulfide side-product 26a (Table 1, entry 1, "standard

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• presence of copper(II) sulfate (reactions 4 and 5, respectively, Scheme 3). The product formation in both cases was ascertained by direct-phase TLC, 1H NMR and reversed-phase HPLC. The monoazido-monotosylated fraction was isolated using reversed-phase PCC with water/methanol gradient elution in 35% yield

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• prepared and their binding properties toward sodium and potassium ions were studied in addition to transition metals. Sakata et al. reported the syntheses and characterization of nickel(II), copper(II) [25] and oxovanadium(IV) [26] complexes of crown ether-annulated DBTAAs, which caused dimerization in the

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• combines the photoredox activation of electron-rich alkenes with copper(II)-mediated oxidation of electron-rich radicals as described by Kochi [18][19][20]. These studies resulted in the development of a general new protocol for oxyamination (Figure 1a) and diamination (Figure 1b) of alkenes. The mechanism

• photocatalyst can be coupled to the reduction of Cu(I) to Cu(0), which can be observed precipitating from solution over the course of the reaction. Copper(II) salts have been demonstrated to be convenient terminal oxidants in a variety of synthetically useful catalytic reactions [23][24][25][26]. They are

• easily handled, are available from commodity chemicals for nominal cost, and present minimal environmental and health concerns in large-scale applications. The use of stoichiometric copper(II) reagents, however, could become prohibitive in certain applications where specific, synthetically laborious

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• of the copper(II) acetate-mediated oxidative radical ring-opening/cyclization of MCPs with diphenyl diselenides is outlined in Scheme 5. Firstly, the phenylselenyl radical 14, generated from the homolytic cleavage of diphenyl diselenide, is added to the C–C double bond of MCPs to afford the

• intermediate 15, which undergoes a ring-opening process to form the radical intermediate 16 [52][53]. Then, the radical 16 reacts with copper(II) acetate to produce organocopper intermediate 17. Finally, the intramolecular insertion of C–Cu in compounds 17 to the carbon–carbon double bond takes place to

• MCPs with elemental chalgogens. Copper(II) acetate-mediated oxidative radical ring-opening and cyclization of MCPs with diphenyl diselenides. AIBN-promoted oxidative radical ring-opening and cyclization of MCPs with benzenethiol. AIBN-mediated oxidative radical ring-opening and cyclization of MCPs with

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• transition metal complexes” [106]. In this mechanism, the catalyst is the most important component: it determines the equilibrium constant between the active and dormant species which is directly linked to the distribution of chain lengths [107]. As photoredox catalysts for ATRP applications, copper(II

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• ” reaction leading to a macrocycle or (ii) an intermolecular “click” reaction forming dimeric or oligomeric compounds. For a deeper insight, the “click” reaction was executed under different reaction conditions. First, the copper(I)-promoted “click” reaction was performed on 2 in the presence of copper(II

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• synthesis of spiro β-lactams via oxidative dearomatization reactions. In this report, the synthesis of spiro β-lactams 56 were achieved successfully by the oxidative cyclization of p-substituted phenols 55 using PIDA (15) as an electrophile and copper(II) sulfate pentahydrate as an additive in the presence

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• below. 3.3.1 Acetoxysulfenylation using copper acetate. Bewick et al. reported a copper(II)-catalyzed synthesis of β-hydroxy sulfides from the reaction of cyclohexene/open-chain olefin with the basic disulfides, namely: 2,2’-dipyridyl disulfide and bis(2-aminophenyl) disulfide [68]. The intermediate 90

• . Due to the absence of this kind of chelation effect, the copper(II) acetate fails to catalyze the addition of diphenyl disulfide to alkenes under the same reaction conditions. 3.3.2 Acetoxysulfenylation using copper iodide-bipyridine as a catalyst. Taniguchi reported a copper(II) iodide-catalyzed 1,2

• -acetoxysulfenylation of alkenes using disulfides and acetic acid as substrates at 90 °C in open air as depicted in Scheme 33 [69]. This regioselective reaction gave the corresponding 1,2-acetoxysulfides in reasonable yields. Unlike a copper(II) acetate-catalyzed reaction which requires long reaction times, the copper

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• catalytic benzoyloxy-trifluoromethylation using Togni’s reagent 5 (Scheme 4 and Scheme 5), the 1,2-benzoyloxy-azidation of alkenes can be performed in the presence of a copper catalyst with the azidobenziodoxolone ABX 40. The reaction takes place in dichloromethane using the copper(II) complex Cu(OTf)2 as

• high yielding N-arylation of 1H-1,2,3-benzotriazole (BTA), utilizing symmetrical diaryl-λ3-iodanes as two-fold aryl donors has been reported in the presence of Pd(OAc)2 and TPPTS as a water-soluble ligand, and copper(II) phenylcyclopropylcarboxylate (Scheme 35) [74]. Noteworthy, it is mentioned that Ar

Synthesis of trifluoromethylated 2H-azirines through Togni reagent-mediated trifluoromethylation followed by PhIO-mediated azirination

• Jiyun Sun,
• Xiaohua Zhen,
• Huaibin Ge,
• Guangtao Zhang,
• Xuechan An and
• Yunfei Du

Beilstein J. Org. Chem. 2018, 14, 1452–1458, doi:10.3762/bjoc.14.123

• has been proposed and is outlined in Scheme 5. Initially, CuI catalytically activates the Togni reagent 1, leading to the formation of the CF3-containing radical intermediate 9. Decomposition of the intermediate 9 produces (2-iodobenzoyloxy)copper(II) iodide (10) [65][66] with the simultaneous release

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• -carboxylate in good yield. Copper(II) acetate anchored on a modified silica gel can also serve as an efficient catalyst in batch reactor or if housed in stainless steel cartridges [127] in continuous-flow conditions (Table 10). Again, the 4-substituted pyrazole is preferentially formed. Conclusion Since its

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• characterized three mononuclear copper(II) complexes, [Cu(tpy)Cl2], [Cu(tpy)(NO3)2(H2O)] and [Cu(Ptpy)Cl2]·H2O·HCl and investigated their cytotoxicity and primary mode of DNA binding mechanism [94]. Molecular modeling as well as DNA cleavage studies have revealed that the first two complexes are DNA minor

• interactions play a crucial role in its binding to DNA groove. Similarly, the same group recently reported a macrocyclic copper(II) complex, ([CuL(ClO4)2] where L is 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane) and studied its interaction with calf thymus DNA (ct-DNA). It was confirmed that the Cu(II

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• synthesis of dendrimers and their applications as nanoreactors and catalyst carriers have been extensively studied over the last decades [94][95][96]. Fan and co-workers incorporated a bis(oxazoline)-copper(II) complex in the hydrophobic core of a polyether dendrimer [11]. The copper catalytic complex was

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• , copper(II) species A. The latter reacts with the hydrazone to the trifluoromethylated aminyl radical intermediate C which is stabilized by the lone pair of the adjacent nitrogen atom, and (2-iodobenzoyloxy)copper(II) chloride (B). Finally, intermediate C is oxidized by copper(II) to restore the hydrazone

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• means for the detection of copper(II) salts [65][66][67] and ascorbic acid [68], and also for protein quantification (i.e., for proteins capable of reducing Cu(II) to Cu(I)) [69]. The basis of these detection systems was that two sets of AuNPs were synthesized, one of which was functionalized with azide

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

•  69) [20], Langlois and co-workers demonstrated that enol acetates 1a–c were converted into the corresponding α-trifluoromethyl ketones upon treatment with CF3SO2Na with tert-butyl hydroperoxide (TBHP) and a catalytic amount of copper(II) triflate (Scheme 1) [21]. The scope was rather narrow and

• CF3SO2Na in the presence of copper(I), reacted at the more electron-rich carbon atom of the C=C double bond to give the radical species 5 that was oxidised by copper(II) into the corresponding cationic intermediate 6 via a single electron transfer (SET). Finally, the acetyl cation was eliminated to provide

• aminotrifluoromethylation of alkenes in an intramolecular version was reported by Zhang and co-workers in 2017 (Scheme 14) [33]. Langlois’ conditions with tert-butyl hydroperoxide and a catalytic amount of copper(II) triflate were used to prepare a series of CF3-containing indoline, pyrrolidine, lactam and lactone

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• reactions [27][28][29][30]. Significantly shortened reaction time and reduced energy requirements, along with clear benefits in yields revealed a wide potential of the mechanochemical approach for CuAAC. The initial report showed applications of standard catalyst systems, copper(II) salts and ascorbic acid

• situ generated Cu(I) through the reduction of Cu(II). Conventional solution-based CuAAC reaction using copper(II) acetate monohydrate was applied to provide triazoles 5–8. Two modes of heating the reaction mixture were used in order to test the reactivity of the azide reactants: heating at 60 °C for

• , entry 4). Solution-based method 1b using CuI, N,N’-diisopropylethylamine (DIPEA) and acetic acid afforded compounds 5–7 in 5–52% isolated yield and was thus less successful for the synthesis of 5–8 derivatives than methods 1a and 1a*, which include copper(II) acetate monohydrate as catalyst. Methods 1a

Preparation of imidazo[1,2-a]-N-heterocyclic derivatives with gem-difluorinated side chains

• Layal Hariss,
• Kamal Bou Hadir,
• Mirvat El-Masri,
• Thierry Roisnel,
• René Grée and
• Ali Hachem

Beilstein J. Org. Chem. 2017, 13, 2115–2121, doi:10.3762/bjoc.13.208

• [24]. Herein, we report the synthesis of imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazopyridazines with fluorinated side chains following an efficient strategy developed by Hajra et al. [25]. This methodology, developed for the synthesis of 3-aroylimidazopyridines, involves a copper

• (II) acetate-catalyzed aerobic oxidative amination and it proceeds through a tandem Michael addition followed by an intramolecular oxidative amination. Therefore, our target molecules A could be synthesized by the oxidative coupling of 2-aminopyridines with α,β-unsaturated ketones B, themselves easily

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• many cases 3,6-unsubstituted carbazoles have been nitrated by using fuming or 70% nitric acid with or without addition of acetic anhydride [46]. Two inorganic nitrates, such as copper(II) nitrate [47] or cerium(IV) ammonium nitrate (CAN) [48] have also been used to give 3-mononitro or 3,6-dinitro

α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones

• Liquan Tan,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2017, 13, 1079–1084, doi:10.3762/bjoc.13.107

• been made [12], examples of the synthesis of α-acetoxyaryl ketones through self-intermolecular oxidative coupling of aryl ketones are still rare. Yan and coworkers reported the preparation of α-acyloxyaryl ketones from aryl ketones using a Pybox-copper(II) catalyst [13]. However, the substrate scope

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• -deficient aryl bromides provided good to excellent yields. D-Glucose represents a type of environmentally friendly ligand and can be easily removed during the work-up process. This work is of special value as it was the first report employing copper(II) as the catalyst in the synthesis of phenols. In 2011