Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons

• Goki Hirata,
• Yu Yamane,
• Naoya Tsubaki,
• Reina Hara and
• Takashi Nishikata

Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45

• ][14][15][16]. Recently, we have prepared quaternary carbon centers via radical reactions by using α-bromocarbonyl compounds (a tertiary alkyl source) and olefins or heteroatoms in the presence of a copper catalyst [17][18][19]. During our studies, we found that combinations of alkynes and tertiary

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• , and no significant selectivity was observed when nonsymmetrical iodonium salts were reacted under the optimized reaction conditions. Later in 2015, Greaney and co-workers described the copper-photocatalyzed azidation of styrene olefins and the concomitant introduction of a nucleophile (Scheme 9) [26

• heteroaromatic derivatives. Noteworthy, when the reaction was carried out in acetonitrile, azido bromination and diazidation reactions were possible using 10 equivalents of NaBr and NaN3, respectively. Notably, when the reaction was carried out in the dark, the diazidation reaction of the olefins occurred, while

• -substituted olefins (Scheme 17) [33]. The reaction was carried out using the complex [Cu(I)(dmp)(binap)]PF6, and the desired tribromomethylated products were isolated in good to excellent yields. The authors suggested a similar mechanism to the one described by Reiser and co-workers in Scheme 14. In 2018, Hu

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• substrate 1. Recently, acetonitrile was reported as a nontoxic source of cyanide [19][20]. Having the optimized conditions in hand, the scope of this transformation was examined using selected olefins and the substrate containing imidazo[1,2-a]pyridine ring embedded either within 2-(diethoxyphosphoryl

• -(bromoimidazo[1,2-a]pyridin-3-yl)-2-(diethoxyphosphoryl)acrylates 1 and propionates 2 using microwave-assisted Mizoroki–Heck reaction. The method worked for a number of olefins, enabling the functionalization of the heterocyclic ring with diverse groups, which can be used for further modifications. Importantly

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

• Qiao Li,
• Chen Zhuang,
• Donghua Wang,
• Wei Zhang,
• Rongxuan Jia,
• Fengxia Sun,
• Yilin Zhang and
• Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

• reagents have emerged as a class of efficient and environmentally benign nonmetal “green” oxidants [66][67][68][69][70][71][72][73]. For instance, iodosobenzene (PhIO) [74] has been widely used in many synthetic transformations. It was found that PhIO is efficient in realizing epoxidation of olefins [75

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• of a poly-ʟ-valine 6 coated graphite cathode for asymmetric electrochemical reductions in two consecutive reports. In the first communication, they carried out the asymmetric reduction of prochiral activated olefins 5 and 8, affording 7 and 9 with optical yields of 25% and 43%, respectively (Scheme 3

• investigated the asymmetric electrodihydroxylation of olefins 69 in an undivided cell under constant current using potassium osmate as a catalyst in presence of Sharpless ligand and using iodine as the oxidizing mediator (Scheme 27). Two sets of conditions were developed, and they differ in the inorganic bases

• used; method A involves K2CO3, whereas method B uses a mixture of K3PO4 and K2HPO4. However, olefins 69 were converted to the corresponding dihydroxylated products 70 in excellent yields as well as enantiomeric excesses regardless of the nature of the substituent or reaction conditions [64]. Further

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

• Sergey A. Dobrynin,
• Igor A. Kirilyuk,
• Yuri V. Gatilov,
• Andrey A. Kuzhelev,
• Olesya A. Krumkacheva,
• Matvey V. Fedin,
• Michael K. Bowman and
• Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

• to the N–O· group. Keywords: domino reactions; EPR; nitroxide; spin relaxation; Introduction Domino reactions have attracted much attention as an approach for the synthesis of complex molecules in a few steps [1]. The utility of multicomponent reactions involving amines, activated olefins and

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

• catalyzed by metals. However, there are only a few methods available for the C(sp3)–CF3 bond formation and this transformation still needs further examination. C(sp3)–CF3 bond formation Copper catalysis: In 2011, two Cu(I)-catalyzed allylic trifluoromethylation reactions of terminal olefins have been

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• the general yields of 3-carboxy-quinolines obtained in our initial study. Two previous observations in our lab, one made in our cyclopropanation–ring expansion study of indoles, and one made during our initial reactions of X-EDAs with olefins [35], gave us the clues for how to quickly improve the

• yield of 9. Cl-EDA gave a small, but significant increase in yield compared to Br-EDA in our previous study (90% vs 84% yield, Scheme 1). The cyclopropanations of olefins with X-EDAs were very sensitive to the choice of solvent, and the yields increased dramatically on going from CH2Cl2 to toluene. When

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• together with 1.5 equivalents of 3a led to a higher conversion (ca. 90%), affording acceptable yield and selectivity (Table 1, entry 5). With optimized reaction conditions in hand (Table 1, entry 5), we then examined the generality of this four-component radical cascade reaction using xanthates 1, olefins

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• reactions of hydantoins [41][59]. However, also using this oxidant, we observed low conversions (31%) and the formation of significant amounts of byproducts, mainly halides and olefins (elimination byproducts). The use of liquid-assisted grinding (LAG) procedures [60][61][62] by adding small quantities of

• citrate) resulted in low alcohol-to-aldehyde conversions (<40%) and promoted, conversely, the formation of significant amounts of olefins (>25%) resulting from halide elimination. Any attempt to lower the amount of the nitrosyl catalyst resulted in a poor conversion (69%, Table 2, entry 5). Once the

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

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

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• , this latter holding the aliphatic side chain but also often having oxygenated functions [11]. Similarly, rings B and C can be naturally functionalized with a varied set of groups including hydroxy, carbonyl and olefins, which along with those present in rings A and D and the side chain are the basis of

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• for C10H13ClN2O3S, 276.7350; found, 277.0434. The dipolar intermediate formed in the reaction of CSI with olefins. (a) Molecular structure of racemic molecule 10 (asymmetric unit). Thermal ellipsoids are drawn at the 30% probability level. (b) Geometric parameter with H-bonded geometry. Hydrogen bonds

• are drawn as dashed lines. (c) Stacking motif with the unit cell viewed downward along the c-axis. Dashed lines indicate C–H∙∙∙O interactions. Relative energy profile of the reaction mechanism shown in Scheme 4. The reaction of CSI with olefins. The synthesis of imide 9. The synthesis of ylidene

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• across olefins [56][57]. It is worth to note in the end of this part, that we did not detect formation of chlorine-containing products (molecular peaks with the isotopic distribution characteristic for chlorine were absent in GC–MS spectra). Conclusion The present work reports an efficient method for the

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• transition metal-mediated, regioselective, chelation-directed activation of an aryl–hydrogen bond. A promising approach was seen in an application of Murai’s elegant ruthenium-catalyzed ortho-functionalization of aryl alkyl ketones and their addition to olefins [11][12][13][14][15]. This route appeared

• substitutions was opened based upon Murai’s ruthenium-catalyzed hydroarylation of olefins. Thus, the aglycon of scorzodihydrostilbene D became accessible in two steps from readily available starting materials. Experimental General: Melting points (uncorrected) were determined with a Büchi 540 melting point

Intramolecular cascade annulation triggered by rhodium(III)-catalyzed sequential C(sp²)–H activation and C(sp³)–H amination

• Liangliang Song,
• Guilong Tian,
• Johan Van der Eycken and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 571–576, doi:10.3762/bjoc.15.52

• components (such as olefins, alkynes) stands out for the construction of carbo(hetero)cycles from easily available starting materials [7][8][9][10]. Compared to aromatic C(sp2)–H bonds, studies on activation of vinylic C(sp2)–H bonds have been less explored, due to an intrinsic inactivity, tended to undergo

• highly substituted olefins using acrylamides. However, most of them are limited to one-step coupling or annulation and just a single ring is formed [15][16][17][18][19][20][21][22]. Therefore, it is necessary to explore a new cascade annulation of acrylamides to construct a polyfused-heteroarene skeleton

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• ). In the ROMP of the norbornene derivative 13, ArM 6 and ArM 7 performed best, outperforming catalyst 9. A near ten-fold increase is observed for ArM 6 (Table 10, entry 2). In the cross metathesis of terminal olefins 73, 74, and 75, with the commercial catalyst 9 conversions of 79%, 98% and 94

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• ][4], however, there are certain negative aspects of thiols that need to be taken into account (i.e., foul smell, easy oxidation into disulfide, participation as donors in one-electron events, reaction with olefins through ene-type reactions, etc) [5][6][7][8]. Hence, the development of thiol-free

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• reagents [39][40] with various halo derivatives (e.g., aryl, vinyl, benzyl, or allyl) and has a broad scope to assemble diverse targets. This reaction was first reported in 1977, and it is an elegant and versatile method that allows the preparation of biaryls and olefins in good yields. To the best of our

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• silsesquioxanes (POSS) and POSS-containing polymeric materials. Three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis polymerization (ROMP) of

• reactivity is the inactivity of vinylsilsesquioxane in homometathesis. The limitations apply to silanes containing a double bond located directly at the silyl group and do not apply to allylsilanes and other alkenylsilanes, which behave like terminal olefins and readily undergo metathesis. Application of

• metathesis in chemistry of unsaturated derivatives of POSS is limited to three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis

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

• derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be

• skeletons and their easy availability [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The cyclopropane derivatives, especially methylenecyclopropanes [17][18][19][20][21], cyclopropyl olefins [22] and cyclopropanols [23][24] undergo ring-opening/cyclization reactions to provide a huge number of

• methylenecyclopropanes (compounds A). The cyclopropyl-substituted carbon radical D easily goes through a ring-opening to generate the alkyl radical E, and then cyclizes with the phenyl ring to afford the terminal product F (path I). The cyclopropyl olefins (compounds B) also react in the same cyclopropyl-substituted

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• metathesis reactions on polymers were mostly studied with regard to the intramolecular polymer–catalyst interactions [77][78][79] or intermolecular degradation of polymers via the cometathesis with different olefins [77][80][81]. Only recently, the cross metathesis between macromolecules, or macromolecular

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• transfer; cyclopropane; cyclopropylcarboxylate; ethylene cyclopropanation; ethyl diazoacetate; gold catalysis; Introduction Nowadays the olefin cyclopropanation through metal-catalyzed carbene transfer starting from diazo compounds to give olefins constitutes a well-developed tool (Scheme 1a), with an

• formation of electrophilic metal–carbene intermediates LnM=CRR’ [1][2] that further react with nucleophiles such as olefins en route to cyclopropanes. However, these intermediates can also react with another molecule of the diazo reagent promoting the formation of olefins RR’C=CRR’ [17]. This side reaction

• . The complex TpMsCu(thf), previously described as an excellent catalyst for olefin cyclopropanation [18], led to negative results, since only the olefins 2 (mixtures of diethyl fumarate and maleate) were detected at the end of the reaction. The second copper-based catalyst tested Tp(CF3)2,BrCu(thf) [19

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

• Fabienne Speck,
• David Rombach and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

• -phenylphenothiazine derivatives 1–11 as photoredox catalysts. Three of them were identified to be highly suitable for the addition of methanol to alkenes affording the corresponding Markovnikov products. Results and Discussion Activated aromatic olefins, such as 1,1-diphenylethylene (12), have reduction potentials

• Ered(S/S−·) in the range of −2.2 to −2.3 V [23][24], α- and β-methylstyrene (13a and 13b) have an Ered(S/S−·) of −2.5 to −2.7 V [25], and styrene (14) an Ered(S/S−·) of −2.6 V (Figure 1) [25][26]. For non-aromatic, alkylated olefins, like 1-methylcyclohex-1-ene (15), the reduction potentials are

• -diphenylethylene (12), but not yet α-methylstyrene (13), and clearly not non-aromatic (alkylated) olefins, such as methylated cyclohexene 15, as basic structures. The absorption of N-phenylphenothiazine (1) disappears at around 390 nm. This feature requires the excitation of the molecule using UV light sources and