Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• moiety (OCH2CF3), an important fluorinated group found in several bioactive compounds such as flecanide [154][155] and lansoprazole [156], as flagship molecules. Although the transition-metal-catalyzed hydroxylation and alkoxylation have been studied especially under palladium catalysis [157][158], the

• [h]quinoline under palladium catalysis in the presence of PhI(OAc)2 as oxidant (Scheme 19) [161]. Since this seminal work and in the course of their investigation towards the development of new methods for the alkoxylation of C(sp2) centers by transition-metal catalysis, few examples of transition

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

• also reported the Co-catalyzed C–H alkoxylation of ferrocenes under nearly room temperature [38]. In comparison, despite the direct C–H amination of arenes with alkylamines has emerged as an efficient strategy to prepare substituted anilines [39][40][41][42][43][44][45][46][47][48][49], the application

• amination occurred selectively at the ortho position to the N-quinolinyl amides with acceptable yields (3f–l). Notably, free alcohol was also compatible with this protocol, exclusively giving the mono-aminated product in 73% yield (3m) without the observation of any competitive alkoxylation product [38][57

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

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• work was extended to incorporate these modifications into oligonucleotides containing all four bases [202]. N-Iodosuccinimide promoted the alkoxylation of the 4'–5'-enol acetates yielded the corresponding 5'-acetoxy-5'-iodo-4'-methoxy intermediates [202]. These intermediates were hydrolyzed with a

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

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

• conditions or heated ion exchange resin [21][22]. These methods are therefore not suitable for the alkoxylation of acid or base-labile substrates. To overcome the current limitations of reduction potentials of single electron transfer processes in photoredox catalysis we present herein a range of new N

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• 2-quinolones 8p/8p’ and TFE-adduct 9b (Table 2, entry 1). However, the application of branched fluorinated alcohols as solvent solved the problem of the competing alkoxylation reaction. Thus, no alcohol adducts were formed when the gold-catalyzed cyclization of 7p was conducted in hexafluoro-2

• concomitantly promoted the competing alkoxylation reaction (Table 3, entries 1 and 2). Consequently, we were able to isolate and characterize the corresponding TFE-adduct 9c (Table 3, entry 2). Switching to HFIP as the solvent prevented the alkoxylation but led to an even slower reaction rate (Table 3, entries

• in TFE did not lead to a full conversion within 12 h at rt (Table 4, entry 1). Switching to branched fluorinated solvents led to a faster conversion of 7r simultaneously suppressing the competing alkoxylation (Table 4, entries 2–4). Nonetheless, the transformation of 7r was further complicated by the

Cobalt-catalyzed peri-selective alkoxylation of 1-naphthylamine derivatives

• Jiao-Na Han,
• Cong Du,
• Xinju Zhu,
• Zheng-Long Wang,
• Yue Zhu,
• Zhao-Yang Chu,
• Jun-Long Niu and
• Mao-Ping Song

Beilstein J. Org. Chem. 2018, 14, 2090–2097, doi:10.3762/bjoc.14.183

• Jiao-Na Han Cong Du Xinju Zhu Zheng-Long Wang Yue Zhu Zhao-Yang Chu Jun-Long Niu Mao-Ping Song College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, People’s Republic of China 10.3762/bjoc.14.183 Abstract A cobalt-catalyzed C(sp2)–H alkoxylation of 1

• system. Moreover, a series of biologically relevant fluorine-aryl ethers were easily obtained under mild reaction conditions after the removal of the directing group. Keywords: alkoxylation; C–H activation; cobalt catalysis; 1-naphthylamines; secondary alcohols; Introduction Aryl ethers are common

• rapidly in recent years. By contrast, alkoxylation or phenoxylation confronts great challenges because alkanols or phenols are easily converted into the corresponding aldehydes, ketones, or carboxylic acids [7][23][24][25]. Recently, Gooßen [26][27], Sanford [28], Song, [29][30] and others [31][32][33][34

Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis

• Tatiana Golub and
• James Y. Becker

Beilstein J. Org. Chem. 2018, 14, 861–868, doi:10.3762/bjoc.14.72

• : anodic oxidation; bisamides; constant current electrolysis; methoxylation; Introduction It is well known that the anodic oxidation of amides involving a hydrogen atom at the α-position to the N atom could undergo alkoxylation, carboxylation and hydroxylation at this position [1][2][3][4][5] (Scheme 1

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

• developed by the Kamal and Nagesh group [65]. In their reaction system, oxone was used as oxidant, Cs2CO3 as base and DMF as solvent (Scheme 36). The reaction occurred at 120 °C and afforded the corresponding phenols in moderate yields. The catalytic system could also be used for alkoxylation of 2

A new method for the synthesis of α-aminoalkylidenebisphosphonates and their asymmetric phosphonyl-phosphinyl and phosphonyl-phosphinoyl analogues

• Anna Kuźnik,
• Roman Mazurkiewicz,
• Mirosława Grymel,
• Katarzyna Zielińska,
• Jakub Adamek,
• Ewa Chmielewska,
• Marta Bochno and
• Sonia Kubica

Beilstein J. Org. Chem. 2015, 11, 1418–1424, doi:10.3762/bjoc.11.153

• alkoxylation or aryloxylation of this position [20][29][30]. As we demonstrated, electrophilic activation of the α-carbon of 1-aminophosphonates can easily be achieved by electrochemical α-methoxylation of these compounds in methanol, mediated with NaCl (Scheme 1, Table 2). α-Methoxylations were carried out in

• failed, probably due to the steric hindrance exerted by a bulky substituent at the α-position. Electrochemical α-alkoxylation of N-acyl-α-amino acid esters mediated by NaCl, NaBr, LiCl, KCl or KI is a well-known reaction [38][42][43][44][45][46], whereas the analogous reaction of N-acyl-α-aminophosphonic

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• blocks for further transformations which are under current investigation. Conclusion In conclusion, we have developed the alkoxylation of 1,4-dienols by electrochemically generated selenium and iodonium cations. First, the synthesis of 1,4-dienols via a cobalt-catalysed 1,4-hydrovinylation of substituted

• desired 1,4-diene. General procedure for the electrochemical seleno-alkoxylation of 1,4-dienols An undivided electrolysis cell was charged with diphenyl diselenide (78 mg, 0.25 mmol, 0.5 equiv), tetraethylammonium bromide (11 mg, 0.05 mmol, 0.1 equiv), the 1,4-diene (0.5 mmol, 1.0 equiv) and 10 mL

• ), dried over Na2SO4 and the solvent was removed under reduced pressure. The product was obtained after column chromatography (n-pentane/diethyl ether). General procedure for the electrochemical iodonium-induced alkoxylation of 1,4-dienols An H-type divided cell (4G glass filter) was equipped with a carbon

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• reactions of CH- and OH-reagents, closely related C–H activation processes involving intermolecular C–O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.). Keywords: acyloxylation; alkoxylation

• 6 to form 7) [42], benzoxazole (acetoxylation of 8 to form 9) [43], benzimidazole (alkoxylation of 10 to form 11) [44], and triazole (acyloxylation of 12 to form 13 [45], alkoxylation of 14 to form 15 [46]) moieties were also used as directing groups for the ortho-acyloxylation and alkoxylation of

• arenes (Scheme 4). The pyridine, pyrimidine, or pyrazole moiety serves as the directing group in the oxidative ortho-alkoxylation of arenes 16 with the Cu(OAc)2/AgOTf/O2 system giving coupling products 17 (Scheme 5) [47]. It is supposed that copper is inserted into the C–H bond of arene, the resulting Cu

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• /alkoxylation of amides pre-dates this work [12][13], Shono showed the synthetic utility of combining an electroorganic step with key carbon–carbon bond forming reactions required in synthetic organic chemistry. The key anodic methoxylation is operationally straightforward with a standard electrochemical set-up

• spatially addressable electrolysis platform’s (SAEP) [56]. This technique has been used to prepare both parallel and combinatorial libraries using Shono-type oxidation on a microarray. Some technical aspects of anodic alkoxylation have been patented [57]. The use of the Shono-type electrooxidation in

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• of secondary alcohols. The efficiency of the process relied on the stabilization of cationic [Au(III)] species by using a catalytic amount CuCl2 (16 mol %), which prevented gold deactivation via parasitic reductive side reactions [30][31]. Moreover, recent advances in the alkoxylation of olefins

• be widen to more functionalized substrates, efficiently. For examples Robertson and co-workers reported on the synthesis of (+)-isoaltholactone, by adopting an intramolecular stereoselective Ph3PAuOTf-catalyzed 5-exo alkoxylation of allylic alcohols, to form tetrahydrofuran rings (Scheme 28) [69

• mechanistic cycle for the gold-catalyzed alkoxylation of ethylene with PhOH. Postulated mechanism for the [Au(I)]-catalyzed hydroamination of olefins. [Au(I)]-catalyzed addition of phenols and carboxylic acids to alkenes. [Au(III)] catalyzed annulations of phenols and naphthols with dienes. [Au(III

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• undergo intermolecular alkoxylation-[3,3]-sigmatropic rearrangement under Ag(I) or Au(I) catalysis [7][8], allyl ethers that are less nucleophilic due to steric reasons react more slowly and have not been known to undergo similar reactions until recently. In our previous work [9], it was shown that ester

Exploring chemical diversity via a modular reaction pairing strategy

• Joanna K. Loh,
• Sun Young Yoon,
• Thiwanka B. Samarakoon,
• Alan Rolfe,
• Patrick Porubsky,
• Benjamin Neuenswander,
• Gerald H. Lushington and
• Paul R. Hanson

Beilstein J. Org. Chem. 2012, 8, 1293–1302, doi:10.3762/bjoc.8.147

• -difluorobenzenesulfonyl chloride were sulfonylated with cyclopropyl amine followed by Mitsunobu alkylation with 3-silyloxybutan-1-ol and subsequent one-pot desilylation intramolecular SNAr alkoxylation (Scheme 2). Each of the scaffolds 1–8 was prepared on a 2.5 g scale. With scaffolds 1–8 in hand, efforts were focused on