Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• HAT reagent. Difluorination could be achieved using excess fluoride and HAT reagent. Other nucleophiles were amenable to the reaction conditions, allowing various benzylic functionalisation reactions, including acetoxylation and chlorination. In 2023, Hamashima and co-workers disclosed an analogous

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• ) triflate [123], through an adapted Thiele–Winter acetoxylation reaction. The standard procedure involved the use of acetic anhydride and sulfuric acid catalysis. However, the use of sulfuric acid, a strong acid and oxidizing agent, can produce tar in some cases. In order to get around this problem a

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

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• presence of an aromatic substituent on the sulfur atom is essential for the sulfides to react. Also, lengthening the perfluoroalkyl chain from CF3 to C2F5 or C3F7 resulted in a significant drop in the yield. Interestingly, while the electrochemical acetoxylation of 213a furnished 204a in an excellent yield

• methoxylation or acetoxylation, respectively (Scheme 53). The driving force in this reaction is assumed to be the deprotonation of radical cation 215, a highly destabilized species due to the presence of the strongly electron-withdrawing CF3 substituent, which leads to radical 216, synergistically stabilized by

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• using NMR spectroscopy and DFT calculations [33]. In particular, the unprecedented double α-oxygenation of bipyrroles was shown to occur through stepwise acetoxylation, which we found to compete with α–α oligomerization. These new bipyrrole boomerangs exhibited enhanced fluorescence with Φfl values of

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• -iodate system is functioning by a radical-based mechanism where iodine generated in situ captures formed benzylic radicals. The benzylic iodide intermediate then solvolyzes to yield the product ester. Keywords: acetoxylation; benzylic; iodate; NHPI; oxidation; radical; Introduction The ability to

• abstraction catalyst than the chlorine radical allowed for the more selective tertiary acetoxylation of adamantane [51]. Nitroxyl radicals formed from species such as NHPI are well studied H-atom abstraction catalysts often used in the functionalization of hydrocarbons [41]. Building upon the ability to

• selectively acetoxylate the tertiary position of adamantane, we sought to apply this approach to the selective acetoxylation of benzylic C–H bonds. As shown in Figure 1, the use of ammonium iodate in combination with an NHPI-type catalyst yielded efficient benzylic oxidation of n-butylbenzene (1a) to 1

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

• –C or C–heteroatom bonds has attracted more attention [8][9][10][11][12][13]. In particular, the formation of C–O bonds is widely used in the syntheses of pharmaceuticals and functional materials [14][15][16][17]. The direct hydroxylation [18][19] and acetoxylation [20][21][22] have been developed

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• halofunctionalizations of acyclic monoterpenoids were performed using a combination of a hypervalent iodine(III) reagent and a halide salt. In this manner, the dibromination, the bromo(trifluoro)acetoxylation, the bromohydroxylation, the iodo(trifluoro)acetoxylation or the ene-type chlorination of the distal

• our previous study on the bromination of enamides [11]. Thus, using a slight excess of DIB along with a two-fold amount of lithium bromide at 0 °C in dry acetonitrile rapidly yielded dibromo adduct 2a in 91% yield (Table 1, entry 1). Switching the reaction conditions to bromo(trifluoro)acetoxylation

• 5a was obtained in 70% yield (Table 1, entry 7). Interestingly, no traces of the diiodo compound were observed even if the hypervalent iodine(III) reagent was slowly added. Transposing the previously optimized bromo(trifluoro)acetoxylation conditions but using TBAI instead of KI did not improve the

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• benzylic acetoxylation and benzoyloxylation of alkylbenzenes, where an in situ-generated sulfonamidyl radical is the essential radical mediator that effectively abstracts the benzylic hydrogen [49]. More recently, Maruoka et al. succeeded in the photolytic benzylic C–H bond oxygenation of alkylbenzenes

• adding extra acetic acid, the benzylic acetoxylation was further improved to provide an 86% yield of product 2a. Since most of the sodium bromide was present as a precipitate in the flask, the reaction was found to work even with catalytic amounts of the bromide activator (Table 1, entry 8). Other

• ), the corresponding benzyl bromides were mainly obtained along with a small amount of the target C–H acetoxylation product; this byproduct formation might imply the intermediacy of these organic bromides before the production of benzyl acetates. Hence, the reaction system was modified to include zinc(II

Hypervalent iodine(III)-mediated decarboxylative acetoxylation at tertiary and benzylic carbon centers

• Kensuke Kiyokawa,
• Daichi Okumatsu and
• Satoshi Minakata

Beilstein J. Org. Chem. 2018, 14, 1046–1050, doi:10.3762/bjoc.14.92

• Kensuke Kiyokawa Daichi Okumatsu Satoshi Minakata Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan 10.3762/bjoc.14.92 Abstract The decarboxylative acetoxylation of carboxylic acids using a combination of PhI(OAc)2 and

• . Keywords: acetoxylation; carboxylic acids; decarboxylation; hypervalent iodine; iodine; Introduction The decarboxylative functionalization of carboxylic acids and the derivatives thereof is an important transformation in organic synthesis. In recent years, increasing efforts have been devoted to the

• reaction, namely acetoxylation, via the oxidative displacement of an iodine atom of the in situ generated alkyl iodide by PhI(OAc)2 [26]. Herein, we report on the decarboxylative acetoxylation of carboxylic acids that contain an α-quaternary carbon center using PhI(OAc)2 and I2 in a CH2Cl2/AcOH mixed

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

• Shulei Pan,
• Hang Jiang,
• Yanghui Zhang,
• Yu Zhang and
• Dushen Chen

Beilstein J. Org. Chem. 2016, 12, 1302–1308, doi:10.3762/bjoc.12.122

• research on the properties and application of tetraphenylene derivatives. Keywords: acetoxylation; carbonylation; halogenation; tetraphenylene; transition metal; Introduction Tetraphenylene (1) is one of the simplest motifs in the eight-membered ring aromatic compounds (Figure 1) [1][2]. Based on its

• acetoxylation a highly interesting reaction. The Sanford and Wang group, respectively, developed a highly efficient palladium and gold-catalyzed direct acetoxylation of arenes with iodobenzene diacetate [48][49]. Based on these excellent works, we surveyed the reaction conditions for the acetoxylation of

• that aliphatic nitriles 4j,k were also found to be reactive under the conditions. Conclusion In conclusion, three reactions for halogenation, acetoxylation, and carbonylation of tetraphenylene (1) have been developed via a transition-metal-catalyzed direct derivatization. The reactions provide new

Direct access to pyrido/pyrrolo[2,1-b]quinazolin-9(1H)-ones through silver-mediated intramolecular alkyne hydroamination reactions

• Hengshuai Wang,
• Shengchao Jiao,
• Kerong Chen,
• Xu Zhang,
• Linxiang Zhao,
• Dan Liu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2015, 11, 416–424, doi:10.3762/bjoc.11.47

• ), deoxyvasicinone was subjected to a free-radical bromination using NBS and the subsequent treatment with NaOAc/AcOH as an acetoxylation reagent [12]. However, for most of these synthetic strategies harsh reaction conditions are a necessity, produce unstable sulfonamide anhydride intermediates [2][13], which are

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• electrochemical acetoxylation of cholesterol at the allylic position. Direct anodic oxidation of cholesterol in dichloromethane. A plausible mechanism of the electrochemical oxidation of cholesterol in dichloromethane. The electrochemical formation of glycosides and glycoconjugates. Efficient electrochemical

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

• benzylideneaniline were subjected to the acetoxylation using the Pd(OAc)2/PhI(OAc)2 system [33]. More recently, reactions involving the same and some other directing groups were studied in more detail. In most of the studies, Pd(OAc)2 was used as the catalyst, and PhI(OAc)2 or peroxides served as the oxidants. The

• regioselectivity of the ortho-acetoxylation of meta-substituted arylpyridines and N-arylamides 1 was studied [34]. The acetoxylation occurs mainly at the sterically more accessible para-position relative to the substituent R to form product 2. The lowest regioselectivity (2:3 = 6:1) was observed in the case of R

• , arylethylenes, and arylacetylenes were used as precursors of the acyloxy fragment. The cross-dehydrogenative C–O coupling with 2-arylpyridines 4 proceeds also in the presence of the Cu(OAc)2/O2 system [40] and under electrochemical oxidation in the presence of Pd(II) salts [41]. The pyrimidine (acetoxylation of

P(O)R₂-directed Pd-catalyzed C–H functionalization of biaryl derivatives to synthesize chiral phosphorous ligands

• Rong-Bin Hu,
• Hong-Li Wang,
• Hong-Yu Zhang,
• Heng Zhang,
• Yan-Na Ma and
• Shang-dong Yang

Beilstein J. Org. Chem. 2014, 10, 2071–2076, doi:10.3762/bjoc.10.215

• chiral [1,1'-binaphthalen]-2-yldiphenylphosphine oxide as a substrate [35]. In the process of alkenylation and acetoxylation, the corresponding products 2a and 2b were obtained in moderate yields and high enantioselectivities. Next, we examined the substituent effect with P(O)(p-Tol)2 as a directing

• group: The reactions of alkenylation, acetoxylation, hydroxylation and acylation occurred smoothly. Even if the products were obtained in low to moderate yields, they were optically pure (Figure 1, 2c–f). For the substrate of 4-methoxy substituted binaphthyl, we could achieve the alkenylation product 2g

• alkenylation, acetoxylation and hydroxylation. The OMe group is a relatively small group, so the ee was not very high. If the substituent was OEt, the products of alkenylation and acetoxylation (Figure 1, 2m and 2n) were obtained in moderate yield and the results showed good enantioselectivities. Although the

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

• Mrinal K. Bera,
• Moisés Domínguez,
• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

• reactions of β-ketoenamides 14 and 20 with hydroxylamine hydrochloride provided the symmetric bis(pyrimidine-N-oxide) 28 in 39% yield or the mono-pyrimidine-N-oxide 30 in 54% yield (Scheme 6). The acetoxylation of 2- and 4-alkyl substituted pyridine-N-oxides by treatment with acetic anhydride is known as

Organic synthesis using (diacetoxyiodo)benzene (DIB): Unexpected and novel oxidation of 3-oxo-butanamides to 2,2-dihalo-N-phenylacetamides

• Wei-Bing Liu,
• Cui Chen,
• Qing Zhang and
• Zhi-Bo Zhu

Beilstein J. Org. Chem. 2012, 8, 344–348, doi:10.3762/bjoc.8.38

• , easy handling, clean transformation, and reactivity, which is similar to heavy-metal-based oxidants, including harmful elements, such as Pb(IV), Hg(II), and Tl(III), as well as transition metal-catalyzed processes [24][25][26][27][28][29][30]. Recently, we reported an efficient acetoxylation approach

• to synthesize 1-carbamoyl-2-oxopropyl acetate derivatives by using (diacetoxyiodo)benzene (DIB) (Scheme 1) [31]. During the course of conditional optimization to synthesize 1-carbamoyl-2-oxopropyl acetate derivatives, we surprisingly found that almost none of the desired acetoxylation product was

Hypervalent iodine(III)-induced methylene acetoxylation of 3-oxo-N-substituted butanamides

• Wei-Bing Liu,
• Cui Chen,
• Qing Zhang and
• Zhi-Bo Zhu

Beilstein J. Org. Chem. 2011, 7, 1436–1440, doi:10.3762/bjoc.7.167

• acetate derivatives were synthesized through an acetoxylation process to methylene with the aid of (diacetoxyiodo)benzene (DIB) as the oxidant. Not only mild reaction conditions, but also excellent yields and good substrate scope make the present protocol potentially useful in organic synthesis. Keywords

• : 1-carbamoyl-2-oxopropyl acetate derivatives; C-hetero bond; (diacetoxyiodo)benzene; methylene acetoxylation; Introduction Carbon–carbon, carbon–heteroatom bond formation leading to useful molecular structures is one of the most interesting and challenging research topics in organic chemistry [1][2

• perform an acetoxylation reaction with 3-oxo-N-substituted butanamides (Scheme 1). Results and Discussion Initially, we employed 3-oxo-N-phenylbutanamide (1a) as the model substrate and tried to establish an effective reaction system for the synthesis. The results are shown in Table 1. It was found that