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Search for "C–H bond" in Full Text gives 214 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

  • Alemayehu Gashaw Woldegiorgis and
  • Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

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  • ]. Organocatalytic aryl C–H activation via a nonradical process represents an enormous challenge in organic synthesis, although the nucleophilic aromatic substitution with cleavage of the electrophilic aryl CH bond has only recently been developed by transition-metal-catalyzed aryl C–H activation [57]. In the
  • presence of a chiral phosphoric acid, the azo group has recently been revealed to be a useful moiety that may efficiently activate an aromatic ring for formal nucleophilic aromatic substitution, resulting in the cleavage of the aryl CH bond and direct arylation of the nucleophile [58]. In 2018, Tan and co
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Published 15 Nov 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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  • exchange was observed at the ortho-position of 1a with 3.0 equivalents of CD3CO2D under standard conditions (Scheme 5a). Furthermore, a larger value of kinetic isotope effect (KIE = 2.4) was detected (Scheme 5b). These results indicated that the cleavage of CH bond was most likely involved in the rate
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Published 28 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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  • involved in the HAT process of benzylic CH bond using DMBP as co-catalyst to deliver benzylic radical species 9-IX (Figure 9) [71]. The benzylic radical 9-IX intercepted with the nickel catalytic cycle to result in the desired products 26. The photoredox nickel-catalyzed arylation of α-amino C(sp3)–H
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Published 31 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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  • by treatment with PCC/Celite in dichloromethane (DCM). Finally, treatment with a catalytic amount of CF3SO3H provided the corresponding anthracenes 30a–c in good yields (57–75%) [40]. Metal-catalyzed CH bond activation In 2016, Hong’s group developed a synthetic strategy to generate substituted
  • converted to the substituted anthracenes 109 and 110 by varying the acidic workup procedures. In addition, they prepared 9-chloro-10-phenylanthracene (112) in good yield (87%) through diol 111 [59]. Synthesis of substituted benzo[a]anthracene and dibenzoanthracene derivatives Metal-catalyzed CH bond
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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

Graphical Abstract
  • synthetic methodologies is the CH bond activation process that enables a straightforward access to several important and innovative compounds [14][15][16][17][18]. In the last few years, metals such as ruthenium [19][20][21], rhodium [22][23][24], palladium [25][26][27], and iridium [28][29][30] have been
  • widely applied as catalysts for this matter, including in the synthesis of bioactive substances. Although catalysts based on these metals, are known to be efficient in CH bond activation reactions affording the products in good yields and mild conditions, they are also known to be usually expensive
  • isosteviol derivate furnished a useful and versatile oxathiazinane (46). The betulinic acid-derived sulfamate ester preferentially underwent amination at the γ primary CH bond of the equatorial C23 methyl group with high site- and diastereoselectivity to furnish the oxathiazinane derivative in 76% yield
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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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  • is also oxidized to Mn(III)/L–N3. Azide radical addition to Mn(II)/L to form Mn(III)/L–N3 was considered as a possible route. Concurrently, the photocatalyst is irradiated by blue LED light to induce hydrogen atom transfer (HAT) at the CH bond of substrate 12, generating alkyl radicals and enabling
  • , citalopram (17b), an antidepressant, was also reacted under amination conditions involving HBF4, affording product 19b in good yield and excellent diastereoselectivity (dr > 20:1). Other multiple benzylic CH bond-containing molecules, including a dopamine receptor agonist analogue 17c as well as derivatives
  • , metallonitrene intermediate 18A is formed from the reaction of catalyst 18 with iminoiodinane, which is subsequently transformed to Mn–imido complex 18B via conversion of substrate 17 into a temporary benzylic radical species, wherein CH bond cleavage is proposed to be the rate-determining step (inter- and
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Published 26 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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  • . Later, carboxylate-ligand-assisted CH 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
  • '. The isocyanide is inserted into intermediate 158' to achieve intermediate 159'. A 1,2,3-triazole CH bond activation occurs using palladium, which subsequently undergoes a reductive elimination process to afford final product 154. Likewise, the Pd(0) species is reformed for the next cycle [64]. The
  • −Miyaura cross-coupling produced a series of 5-aryl-4-ethynyl triazoles 136 in the presence of Pd(PPh3)4 as catalyst and K3PO4 as base in 1,4-dioxane as solvent at 100 °C (Scheme 39) [62]. A paper by Sekar et al. described the synthesis of polycyclic triazoles 142 through a domino alkyne insertion and CH
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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

Graphical Abstract
  • prove instrumental for the further diversification of the thus obtained 3-methyleneisoindolin-1-ones 3da–ka. For substrates bearing two potential reactive sites, the annulation selectively took place at the less congested ortho-CH bond (see 3la and 3ma). Moreover, the challenging isonicotinic acid
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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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  • [18][19][20][21]. In the presence of a Brønsted acid source, the alkylmetal bond can be transformed into a CH bond to afford a hydrofunctionalized olefin product (Scheme 1) [22]. The relevance of the formation of new C(sp3)–C(sp3) bonds has led to great efforts to enable the use of carbon
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Published 07 Jul 2021

Icilio Guareschi and his amazing “1897 reaction”

  • Gian Cesare Tron,
  • Alberto Minassi,
  • Giovanni Sorba,
  • Mara Fausone and
  • Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

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  • turn, this next abstracts hydrogen at C-3, regenerating the carrier and continuing the cycle. The CH bond at position 3 of Guareschi imides is unusually weak. Hydrogen abstraction by an alkyl radical and formation of a hydrocarbon CH bond is strongly exothermic (calculated enthalpy change: ≈20 kcal
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Published 25 May 2021

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

  • Asha Budakoti,
  • Pradip Kumar Mondal,
  • Prachi Verma and
  • Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

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  • products [1][2][3][4][5][6][7][8]. Prins and related cyclization reactions [9][10], hetero-Diels–Alder cyclization [11], cyclization onto epoxides [12], Petasis–Ferrier rearrangement [13], intramolecular oxa-Michael reactions [14], cyclization through oxidative CH bond functionalization [15], ring-closing
  • enantioselectivity varied with the polarity of the solvent. The optimization study disclosed that the enantioselectivity increases with the decrease of the polarity of the solvent (Scheme 68). Yu and co-workers reported a novel segment-coupling Prins cyclization involving sequential benzylic/allylic CH bond
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Published 29 Apr 2021

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

  • Zhonglie Yang,
  • Yutong Liu,
  • Kun Cao,
  • Xiaobin Zhang,
  • Hezhong Jiang and
  • Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

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  • complexes are the simplest and most rapid way. In this review, the focus lies on cyclization reactions, C–C-, C–S-, C–B-, C–N-, C–P-, C–O-, and CH bond formation, primarily summarizing the chemical reaction step involving the EDA complex (Table 1) as well as the underlying mechanisms that have appeared
  • reactions, C–C-, C–S-, C–B-, C–N-, C–P-, C–O-, and CH bond formations. The absence of transitional-metal catalysts and photosensitizers is the most profound feature of EDA-complex- mediated reactions in most cases. On the other hand, the reaction conditions are mild, and light is utilized as the only
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Published 06 Apr 2021

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

  • Vladimir Kubyshkin,
  • Rebecca Davis and
  • Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

Graphical Abstract
  • , while the remaining CH bond in Flp acquires an enhanced positive charge due to the electron-withdrawing effect of fluorine. Based on these considerations, a fluoroproline–aromatic-system interaction has been previously utilized in the engineering of a few peptide therapeutics [44][45]. 2.3
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Published 15 Feb 2021

Unexpected rearrangements and a novel synthesis of 1,1-dichloro-1-alkenones from 1,1,1-trifluoroalkanones with aluminium trichloride

  • Beatrice Lansbergen,
  • Catherine S. Meister and
  • Michael C. McLeod

Beilstein J. Org. Chem. 2021, 17, 404–409, doi:10.3762/bjoc.17.36

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  • trichloride; dichloroalkenes; Friedel–Crafts alkylation; rearrangement; trifluoroalkanes; Introduction 1,1-Dichloro-1-alkenes are valuable synthetic intermediates and have been employed in Pd-mediated cross couplings of one or both chlorine atoms [1][2][3][4][5][6][7], carbonylation reactions [8], and CH
  • bond alkynylations of heteroarenes [9]. The 1,1-dichloro-1-alkenyl moiety is found in a number of pyrethroid insecticides including permethrin and marine natural products such as caracolamide A [10] (Figure 1). 1,1-Dichloro-1-alkenes 2 are commonly prepared from the corresponding aldehydes 1 in one
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Published 10 Feb 2021

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp3)–H bond functionalization under solvent- and catalyst-free conditions

  • Divya Rohini Yennamaneni,
  • Vasu Amrutham,
  • Krishna Sai Gajula,
  • Rammurthy Banothu,
  • Murali Boosa and
  • Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

Graphical Abstract
  • to be developed [14]. The formation of new C–C bonds through direct CH bond functionalization in organic chemistry is attractive [15]. Such methodologies are omnipresent and facilitate sustainable organic transformations for the synthesis of complex natural products and pharmaceuticals. In the past
  • years, CH bond functionalization catalyzed by transition metals received a strong emphasis, and other different catalytic systems have also been encouraged [16][17][18][19][20]. Huang and co-workers first realized the addition of alkylazaarenes directly to unsaturated bonds via C(sp3)–H
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Published 23 Dec 2020

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

  • Tetsuya Sengoku,
  • Koki Makino,
  • Ayumi Iijima,
  • Toshiyasu Inuzuka and
  • Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

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  • such as potassium tert-butoxide or sodium hydride resulted in no formation of the desired product 3a because 2a was decomposed under the harsh reaction conditions (Table 1, entries 2 and 3). Thus we opted to employ another substrate 2b bearing a phenylthio group which polarizes the α-CH bond to lead
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Published 13 Nov 2020

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

  • Shakeel Alvi and
  • Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

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  • (DFT) calculations. As we are aware that if the carbene formed is a singlet then a CH bond inserted product is predominating whereas if the dimer is the major product along with the minor CH bond inserted product then the triplet carbene is generated. During their study, they obtained the C–H
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Published 09 Sep 2020

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

  • Shahboz Yakubov and
  • Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

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  • catalysis and photochemistry. Where transition metal catalysis provides one strategy for CH bond activation, transition-metal-free photochemical C–H fluorination can provide a complementary selectivity via a radical mechanism that proceeds under milder conditions than thermal radical activation methods
  • ][51][52][53][54][55][56][57]. Accordingly, the reactivity and selectivity correlate with the homolytic CH bond dissociation enthalpy and polarity matching principles [58][59][60][61][62][63][64]. One of the advantages of polarity matching is that it enables C(sp3)–H bond activations that are not
  • H bond is matched to the HAT catalyst. For example, an electrophilic radical abstracts H atoms selectively from the most electron-rich or “hydridic” CH bond [65]. 1.1.3 Importance of visible light and visible-light photosensitization in synthesis: Unlike many other traditional energy resources
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Published 03 Sep 2020

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

  • Lucas Guillemard and
  • Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

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  • last decade particular attention has been focused on two modern fields, CH bond activation, and visible-light-induced photocatalysis. Couplings through CH bond activation involve the use of non-prefunctionalized substrates that are directly converted into more complex molecules, without the need of a
  • catalyst, able to insert selectively into one specific CH bond. Accordingly, not only waste generation was significantly reduced, but also new retrosynthetic connections were envisioned, allowing the conception of more straightforward synthetic protocols [15][16][17][18][19][20]. Besides, the formation of
  • these two activation modes. The advantages of the dual catalytic systems over traditional monocatalyzed approaches is also discussed, thus illustrating their sustainable character. Review Visible-light-mediated photocatalysis as a sustainable reoxidation strategy In the context of traditional CH bond
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Published 21 Jul 2020

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

  • Alessandra Del Tito,
  • Havall Othman Abdulla,
  • Davide Ravelli,
  • Stefano Protti and
  • Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

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  • -obtained α-oxyalkyl radical intermediates were then trapped by biphenyl (or vinyl) isocyanides to afford functionalized phenanthridines, such as 9.3a (or quinolines) (Scheme 9, path a) [70]. A photogenerated nitrogen-based radical was likewise used to cleave the CH bond α-to-nitrogen in amides to form the
  • ) radicals to isonitriles. Synthesis of 6-(trifluoromethyl)-7,8-dihydrobenzo[k]phenanthridine. Phenanthridine syntheses by using photogenerated radicals formed through a CH bond homolytic cleavage in THF (path a) and N,N-dimethylacetamide (path b). Trifluoroacetimidoyl chlorides as starting substrates for
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Published 25 Jun 2020

In silico rationalisation of selectivity and reactivity in Pd-catalysed C–H activation reactions

  • Liwei Cao,
  • Mikhail Kabeshov,
  • Steven V. Ley and
  • Alexei A. Lapkin

Beilstein J. Org. Chem. 2020, 16, 1465–1475, doi:10.3762/bjoc.16.122

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  • -addition, respectively [15]. Even though the mechanisms are inherently different, three most important aspects should be primarily taken into account when classifying and rationalising C–H activation reactions: the proximity of CH bond to the transition metal; the energy of CH bond cleavage within the
  • : https://github.com/sustainable-processes/Pd-catalysed_C-H_activation_reaction_prediction. Results and Discussion Computational approach to rationalise reactivity in Pd-catalysed CH bond activation reactions Chemical reactivity is simultaneously influenced by many factors including catalysts, reactants
  • feature of the proton abstraction (PA) mechanism [25] is that the formation of the metal–carbon bond (M–C) occurs simultaneously with the cleavage of the carbon–hydrogen (CH) bond, while the hydrogen is being transferred to a basic centre, Scheme 1. Assuming the reaction proceeds through the formation of
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Published 25 Jun 2020

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

  • Carlos H. Escalante,
  • Eder I. Martínez-Mora,
  • Carlos Espinoza-Hicks,
  • Alejandro A. Camacho-Dávila,
  • Fernando R. Ramos-Morales,
  • Francisco Delgado and
  • Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

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  • similar chemoselectivity has been previously observed, being explained as a consequence of the acidity of the CH bond being cleaved [6][44]. Additional intramolecular cross-coupling reactions were carried out by utilizing dimethyl malonates 8k and 8l, which were prepared through the N-benzylation of 16c
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Published 17 Jun 2020

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

  • Alexander V. Nyuchev,
  • Ting Wan,
  • Borja Cendón,
  • Carlo Sambiagio,
  • Job J. C. Struijs,
  • Michelle Ho,
  • Moisés Gulías,
  • Ying Wang and
  • Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

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  • recently reported [8][9][11], for example the trifluoromethylation of hydroxyaryls [12][13][14], and the direct introduction of the -OCF3 moiety into an organometallic species [15], a diazo compound [16][17], or an unfunctionalized CH bond (Scheme 1B). The latter method is particularly interesting
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Published 15 Jun 2020

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

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  • reactions of oxime radicals. These reactions are classified into cyclizations involving CH bond cleavage and cyclizations involving a double C=C bond cleavage. Keywords: iminoxyl radicals; isoxazolines; oxidative cyclization; oxime radicals; oximes; Introduction Free radicals in which an unpaired
  • abstraction with cleavage of the CH bond [12][13][14][15][16][17][18] and in the processes of functionalization of С=С double bonds [19][20]. Amidoxyl radicals (Figure 1, III) are applied in the functionalization of the double bonds [21][22][23][24][25][26] and in mild oxidations [27]. In contrast to the
  • oximes reacted with esters and ketones to give oxidative coupling products in moderate to good yields (products 55a–e and 56a–e, respectively). In the case of asymmetric ketones, the CH bond at the more substituted carbon was cleaved (products 56d,e). Recently, the copper-catalyzed addition of oximes to
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Published 05 Jun 2020

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

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  • Photocatalytic hydrogen atom transfer (HAT) represents a valuable strategy for accessing C(sp3) radicals. This method allows the direct cleavage of a CH bond and the consequent generation of alkyl radicals without relying on the presence of redox-active functional groups. This results in a superior atom economy
  • /desulfonylation of the arylsulfonyl chlorides 14.1 (Scheme 14) [85][86]. The ensuing aryl radical is trapped by an aryl isonitrile 14.2, affording the bisarylation product 14.3. The direct organophotocatalytic activation of the CH bond of an arene represents an atom-economical and attractive strategy for the
  • direct activation of the ß-CH bond [109]. However, organic dyes have not yet been broadly applied for such transformations. Charged aryl radical species Arene radical cations are valuable intermediates that enable the direct C–H functionalization of the aromatic species. They can be accessed through the
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Published 29 May 2020
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