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Search for "ligand" in Full Text gives 993 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

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

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Published 04 Nov 2021

Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

  • Tomáš Chvojka,
  • Athanasios Markos,
  • Svatava Voltrová,
  • Radek Pohl and
  • Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

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  • 43 Prague 2, Czech Republic 10.3762/bjoc.17.179 Abstract The stereoselective Suzuki–Miyaura cross-coupling of (Z)-β-enamido triflates is demonstrated. Depending on the nature of the ligand in the palladium catalyst, either retention or inversion of the configuration during the synthesis of β,β
  • (Z)-β-enamido triflates could, during the Suzuki cross-coupling, undergo isomerization of the double bond, similarly to enones, and thus serve as starting materials to either (E) or (Z)-isomers of enamides depending on the conditions used. Here we present a study of the effect of ligand on the
  • configuration of the double bond were formed preferably. Both conditions were applied to a range of arylboronic acids and (Z)-β-enamido triflates. A: Synthesis of (Z)-β-enamido triflates and subsequent stereoselective cross-coupling reactions. B: Ligand-controlled stereoselective synthesis of β,β-diaryl
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Published 29 Oct 2021

Electrocatalytic C(sp3)–H/C(sp)–H cross-coupling in continuous flow through TEMPO/copper relay catalysis

  • Bin Guo and
  • Hai-Chao Xu

Beilstein J. Org. Chem. 2021, 17, 2650–2656, doi:10.3762/bjoc.17.178

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  • reaction of tetrahydroisoquinolines with terminal alkynes (Scheme 1C) [10]. The chiral ligand was found to be critical for the stereoinduction as well as product formation for these electrochemical reactions that are conducted in batch. Continuous-flow electrochemical microreactors offer several advantages
  • electrochemical microreactors can be a viable tool for developing efficient transition-metal electrocatalysis. C(sp3)–H alkynylation of tetrahydroisoquinolines. L* = chiral ligand. TEMPO = 2,2,6,6-tetramethylpiperidine 1-oxyl. DDQ = 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. BPO = benzoyl peroxide. Substrate
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Published 28 Oct 2021

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

  • Scott Benz and
  • Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

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  • catalyst containing the chiral bisoxazoline ligand (S,S)-8 led to the α-ketol rearrangement product 7 in 70% yield and 68% ee (Figure 3) [5]. The study further demonstrated the effectiveness of the catalyst for a series of analogues of 6 bearing various replacements for the phenyl group, often proceeding
  • (Figure 4). These reactions required small adjustments to ligand 11, with m = 1 and Ar = 2,6-Me2C6H3 working best for 12 and m = 0 and Ar = 2,4,6-iPr3C6H2 best for 14. Sc(III) proved to be superior for rearrangement of α-hydroxyaldimines. Under these conditions, products 13 were obtained in poor-to
  • catalyzed by Al(III) or Sc(III) liganded by 11. Ligand 11: for 9, m = 1 and Ar = 2,6-iPr2C6H3; for 12, m = 1 and Ar = 2,6-Me2C6H3; and for 14, m = 0 and Ar = 2,4,6-iPr3C6H2. Asymmetric rearrangement of α,α-dialkyl-α-siloxyaldehydes 16 to α-siloxyketones 17 catalyzed by chiral organoaluminum Lewis acid 18
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Published 15 Oct 2021

Visible-light-mediated copper photocatalysis for organic syntheses

  • Yajing Zhang,
  • Qian Wang,
  • Zongsheng Yan,
  • Donglai Ma and
  • Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

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  • the photocatalyst RuII is irradiated by light, an electron is transferred from the frontier metal d orbital (t2g orbital) to the ligand-centered π* orbital (RuII*). A metal-to-ligand charge transfer (MLCT) results in the excited singlet state. Through rapid intersystem crossing (ISC), the singlet
  • the homoleptic and heteroleptic CuI complexes [22][31][36]. The introduction of bulky ligand substituents might efficiently prevent the reorganization of the excited state. Thus, changing the nature of the chelating ligand can improve the photostability and lifetime of the excited state to meet the
  • . The mechanisms underlying photoredox catalysis of CuI complexes have special features and include ligand exchange and rebound mechanisms [38]. CuII complexes provide new avenues for photoredox catalysis, since CuII can undergo ligand exchange/light accelerated homolysis processes, which accelerates
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Published 12 Oct 2021

In-depth characterization of self-healing polymers based on π–π interactions

  • Josefine Meurer,
  • Julian Hniopek,
  • Johannes Ahner,
  • Michael Schmitt,
  • Jürgen Popp,
  • Stefan Zechel,
  • Kalina Peneva and
  • Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

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  • previous studies, several of these interactions were already applied such as metal–ligand interactions [13][14], hydrogen bonds [15][16] or halogen bonds [17]. Furthermore, π–π interactions also feature a reversible behavior and were therefore utilized for the design of different self-healing polymers [18
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Published 29 Sep 2021

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

  • Zhen-Sheng Jia,
  • Qiang Yue,
  • Ya Li,
  • Xue-Tao Xu,
  • Kun Zhang and
  • Bing-Feng Shi

Beilstein J. Org. Chem. 2021, 17, 2488–2495, doi:10.3762/bjoc.17.165

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  • groups. Kumar and co-workers developed a Cu-mediated C–H chalcogenation and sulfonation of ferrocenes [27][28][29]. The use of a bidentate 1,10-phenathroline ligand was critical to achieve mono-selectivity in the chacogenation reactions [28]. Meanwhile, Co(III)-catalyzed ortho-C–H amidation of ferrocene
  • in 2020, an enantioselective C–H annulation of ferrocenylformamides with alkynes was achieved by the Ye group enabled by Ni-Al bimetallic catalysis and a chiral secondary phosphine oxide (SPO) ligand [35]. Hou et al. also reported the asymmetric C−H alkenylation of quinoline- and pyridine-substituted
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Published 28 Sep 2021

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

  • Azra Kocaarslan,
  • Zafer Eroglu,
  • Önder Metin and
  • Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

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  • -hydroxypropan-1-ol) ether (Az-3), and 1-(prop-2-yn-1-yloxy)-2,2-bis((prop-2-yn-1-yloxy)methyl)butane (Alk-5) as multifunctional click components were irradiated in the presence of BPNs and CuII ligand under NIR light. The gelation was completed after 24 h (Scheme 3). The photocuring process was also followed by
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Published 23 Sep 2021

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

  • Yi Liu,
  • Puying Luo,
  • Yang Fu,
  • Tianxin Hao,
  • Xuan Liu,
  • Qiuping Ding and
  • Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

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  • or ligand in organic chemistry [6][7][8][9][10]. Therefore, the development of efficient methods for the synthesis of pyridine derivatives has attracted considerable attention [11][12][13][14]. The industrial synthetic methods of pyridines mainly involve: i) extraction from coal tar; ii) condensation
  • the bisphosphine ligand DTBM-SEGPHOS (56) was very important to promote the transformation efficiently. The reaction showed a broad substrate scope, with aromatic and aliphatic substrates 54 (R1 = aryl, heterocycle, and alkyl) being good coupling partners, providing the corresponding 2,3-dialkyl-5
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Published 22 Sep 2021

Strategies for the synthesis of brevipolides

  • Yudhi D. Kurniawan and
  • A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

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  • prospective possibility to obtain ent-21 from precursor 20 by utilizing an antipode ligand in a Noyori reduction. As the continuation, intermediate 40 was coupled with (E)-p-methoxycinnamic acid (17) under Steglich conditions and treated with a Lewis acid to remove the MOM protection giving ester 41
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Published 14 Sep 2021

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

  • Janina-Miriam Noy,
  • Fan Chen and
  • Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

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  • observed change in size after ligand attachment, the stability of the particles to disassembly was analysed by measuring the scattering intensity for different polymer concentrations (c = 0–100 µM) and the critical micelle concentration (cmc) values were determined from the intercept point of the linear
  • mitochondria binding ligand does not induce any damaging effects to these cell lines. Many studies have reported that attaching targeting ligands on nanoparticle or liposome surfaces play a key role in overcoming biological barriers and reducing targeting effects. Active targeting or retention can increase
  • target agent carrying nanoparticle surface, the interaction between ligand and targeting agent is inhibited and resulted consequently in significant lower nanoparticle targeting efficiency [48][49]. This study demonstrates that every small change to nanoparticle design can result in unpredictable
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Published 03 Sep 2021

Synthesis of O6-alkylated preQ1 derivatives

  • Laurin Flemmich,
  • Sarah Moreno and
  • Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

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  • thereby regulates genes that are required for queuosine biosynthesis [8][9][10][11][12][13][14][15][16]. The molecular mechanism behind is called riboswitching. For most riboswitches, ligand binding induces a structural change in the untranslated leader sequence of mRNA by formation (or disruption) of a
  • terminator stem (transcriptional control) or repressor stem (translational control). This conformational event signals on or off to gene expression and represents a feedback-type mechanism that is dependent on cellular ligand concentration [13]. Natural occurrence of alkylated prequeuosines Evidence for the
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Published 02 Sep 2021

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

  • Luiz Claudio Ferreira Pimentel,
  • Lucas Villas Boas Hoelz,
  • Henayle Fernandes Canzian,
  • Frederico Silva Castelo Branco,
  • Andressa Paula de Oliveira,
  • Vinicius Rangel Campos,
  • Floriano Paes Silva Júnior,
  • Rafael Ferreira Dantas,
  • Jackson Antônio Lamounier Camargos Resende,
  • Anna Claudia Cunha,
  • Nubia Boechat and
  • Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

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  • ; maximum iteration = 2000; scaling factor = 0.50; offspring scheme = Scheme 1; termination scheme = variance-based; crossover rate = 0.90. Due to the stochastic nature of the algorithm search, ten independent simulations per ligand were performed to predict the binding mode. Consequently, the complexes
  • with the lowest interaction energy were evaluated. The interactions between BCR-Abl-1 and each inhibitor were analyzed using the ligand map algorithm, a standard algorithm in the MVD program [50]. The usual threshold values for H-bonds and steric interactions were used. All figures for molecular
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Published 01 Sep 2021

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

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  • transfer (HAT) and nickel catalysis [54]. The catalytic system consisting of iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6, nickel catalyst NiBr2·3H2O, ligand 4,7-dimethoxy-1,10-phenanthroline (4,7-dOMe-phen), and 3-acetoxyquinuclidine was found to be optimal to afford the desired α-amino C–C coupled
  • identified as the suitable ligand instead of the commonly used bipyridyl ligand (vide supra). Notably, the use of the chiral (S,S)-Bn-BiOx ligand resulted in a moderate enantioinduction in the C‒H arylation product. The authors proposed a catalytic cycle to account for the photoredox nickel-catalyzed C(sp3
  • of aryl chlorides 8 through selective 2-functionalization of 1,3-dioxolane (13) followed by a mild acidic workup (Scheme 9) [61]. Here, the photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and nickel catalyst NiCl2·DME with dtbbpy as ligand, along with K3PO4 as base under irradiation with blue LEDs enabled
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Published 31 Aug 2021

Chemical syntheses and salient features of azulene-containing homo- and copolymers

  • Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

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  • by using [Pd(allyl)Cl]2 and JackiePhos as a ligand to obtain the polymer 30 in 52% yield. The deprotection of the N-Boc functionality led to the formation of poly[2,6-aminoazulene] 31 in excellent yields (Scheme 7C). The N-Boc-protected polymer 30 possessed good solubility in organic solvents and its
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Published 24 Aug 2021

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

  • Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

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  • the desired product 101 in 49% yield [82]. Other copper catalysts such as CuCl or CuBr gave low yields, even when used with 2,2’-bipyridyl as the ligand. First, oxidation of copper(I) takes place, which interacts with elemental sulfur to “activate” it. A nucleophilic attack from N-methylindole (1) to
  • were taken as partners in a Buchwald coupling (Scheme 22a) [44]. On the other hand, in 2015, Organ’s group performed a phosphine-ligand free Buchwald amination of 5-chloroindole (164) with amine 165 to give the desired product 167, where the use of the Pd-PEPPSI-IPentCl precatalyst 166 in presence of
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Published 19 Aug 2021

Recent advances in the syntheses of anthracene derivatives

  • Giovanni S. Baviera and
  • Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

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  • (diphenylphosphino)ethane (DPPE) as ligand improved the yield of the anthraquinones. Representative examples included anthraquinones 179a and 179b obtained from terminal alkynes and 179c and 179d from internal alkynes [75]. Multicomponent reactions In 2009, Singh and co-workers reported a solvent-free methodology to
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Published 10 Aug 2021

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

  • Renato L. Carvalho,
  • Amanda S. de Miranda,
  • Mateus P. Nunes,
  • Roberto S. Gomes,
  • Guilherme A. M. Jardim and
  • Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

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  • scandium(III)/Cp* catalyst containing two units of an o-N,N-(dimethylamino)benzyl ligand [Sc-1] was applied, and several examples of cyclic benzimidazole compounds were obtained in excellent yields (Scheme 2C) [37]. Benzimidazole compounds bearing substituents in their C-2 position are present in several
  • similar catalyst, [Sc-2], which bears a more electron-rich cyclopentadienyl ligand, in a scandium-catalyzed C–H [3 + 2] cyclization (Scheme 5B) [40]. In this transformation, several aminoindane derivatives were obtained from benzylimines in the presence of the catalyst [Sc-2], alkenes and [Ph3C][B(C6F5)4
  • can be formed from I and the Cr(III) salt to start the cycle, thereby providing intermediate VI. The latter then undergoes a ligand exchange with I to give the product and the key intermediate II. It is noteworthy that the secondary amide works both as the substrate and the ligand for the metal center
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Published 30 Jul 2021

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

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  • protein–ligand binding properties as well as biological activities of small molecules, potentially leading to dramatic increases in potency, and thus has been widely explored in drug discovery [54][55][56]. Late-stage C–H methylation has recently been investigated using iron and cobalt catalysts as
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Published 26 Jul 2021

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

  • Girish Suresh Yedase,
  • Sumit Kumar,
  • Jessica Stahl,
  • Burkhard König and
  • Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

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  • benzylic alcohol selectively to the aldehyde or ketone is still desirable. Recently, cerium photocatalysis was introduced as a robust alternative to generate oxygen or carbon-centered radicals under mild reaction conditions [57][58][59][60][61][62][63][64]. CeCl3 reacts via ligand-to-metal charge transfer
  • inhibition of the catalytic cycle upon the addition of TEMPO revealed that the reaction proceeds through radical intermediates. Next, we carried out UV–vis monitoring experiments in order to verify whether the interaction with the substituted benzyl alcohols and CeIV could lead to a ligand-to-metal charge
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Published 23 Jul 2021

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

  • Nikita Brodyagin,
  • Martins Katkevics,
  • Venubabu Kotikam,
  • Christopher A. Ryan and
  • Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

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Published 19 Jul 2021

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

  • Pezhman Shiri,
  • Ali Mohammad Amani and
  • Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

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  • )amine (TTTA) as ligand, and THF as solvent at 50 °C. The obtained sulfonamide-tethered 5-iodo-1,2,3-triazoles 103 were then cyclized upon heating in the presence of Cs2CO3 to give triazole-fused sultams 104. A good to excellent yield of sultam derivatives 104 containing aryl and alkyl substituents on
  • ]. First, the nanocatalyst 139 is inserted in the C–I bond to obtain the intermediate 143. Then, the insertion of diarylacetylenes 141 forms intermediate 144. In continuation, the acetate anion formed by reaction of AcOH with Et3N undergoes a ligand exchange with iodide to produce the intermediate 145
  • . Later, carboxylate-ligand-assisted C–H bond activation takes place through a concerted metalation–deprotonation transformation to produce the next intermediate. Finally, the corresponding product 142 is formed by a reductive elimination process, along with the regeneration of the active catalytic
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Published 13 Jul 2021

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

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  • 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
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Published 08 Jul 2021

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

  • Thiago S. Silva and
  • Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

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  • abstraction, to form a gold complex with a less coordinating ligand that serves as the active catalyst [39]. Following their initial work, the Li group investigated the use of silver triflate as the sole catalyst in the olefin hydroalkylation [40]. In their previous work, they had reported that neither the
  • comparison with the five-membered ones, led to the observation of a mixture of linear and cycloisomerized products when diolefin 36l was subjected to the optimized conditions. The selectivity was improved when a more electron-rich Salen ligand was employed, highlighting the importance of the ligand structure
  • olefins 84 as nucleophile partners and racemic secondary and tertiary α-bromo-N-protected β-lactams 83 under nickel catalysis, along with the chiral bis(oxazoline) ligand 85 and triethoxysilane (Scheme 32) [108]. Substrate structural variations on 84 had only a small impact on the reaction
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Published 07 Jul 2021

Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings

  • Ivan P. Mosiagin,
  • Olesya A. Tomashenko,
  • Dar’ya V. Spiridonova,
  • Mikhail S. Novikov,
  • Sergey P. Tunik and
  • Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105

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  • metal-catalyzed arylation [17][18][19]. We have recently successfully applied this approach to synthesize the new luminescent heterocyclic system pyrido[2,1-a]pyrrolo[3,2-c]isoquinoline A [17], which turned out to be useful for bioimaging [13] and as a ligand for the preparation of luminescent metal
  • ). It is important that the reaction of iodide 1m with 2-pyridyl substituent gave a good yield of the product 3m, which could be used for the preparation of bidentate ligand for metal complexes. Reaction of salts 1 with electron-donating para-substituents (Me, MeO, Me2N) in the pyridine ring (1n–p,s
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Published 23 Jun 2021
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