Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• homoallylic position that assists the electrophilic attack on the double bond [33][34]. The protection of the homoallylic hydroxy group in similar alkenyl diols in epoxidations with the VO(acac)2/t-BuOOH system led to the formation of the erythro isomer [35]. Actually, highly stereoselective epoxidations of

Me₃Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines

• Krishna M. S. Adusumalli,
• Lakshmi N. S. Konidena,
• Hima B. Gandham,
• Krishnaiah Kumari,
• Krishna R. Valluru,
• Satya K. R. Nidasanametla,
• Venkateswara R. Battula and
• Hari K. Namballa

Beilstein J. Org. Chem. 2021, 17, 2765–2772, doi:10.3762/bjoc.17.186

• of isoquinoline N-oxides [41][42], condensation of lithiated o‐tolualdehyde tert‐butylimines with nitriles [43], electrophilic cyclization of 2-alkynylbenzamides [44][45] or 2-alkynylbenzaldoximes [46][47][48][49][50][51][52][53][54], oxidative C–H functionalizations (coupling) on aryl and heteroaryl

• synthesis of a wide array of heterocyclic compounds by creating C–C, C–N, C–O and C–S bonds due to their ability to act as electrophiles. The cyano group is considered as a versatile functional group in various organic syntheses because of its participation in various electrophilic, necleophilic and bipolar

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

• ]. 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 C–H bond has only recently been developed by transition-metal-catalyzed aryl C–H activation [57]. In the

• diarylamines that exist as rapidly interconverting atropisomers, and a VEGFR inhibitor from Wyeth contains a potentially atropisomeric N-arylquinoid [95][96]. In 2020, Gustafson and co-workers reported the first chiral phosphoric acid-catalyzed atroposelective electrophilic halogenation of N-arylquinoids 95, a

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• highly electrophilic N-acyliminium intermediates [17]. As a special aspect, we used a carbamate unit (instead of the commonly used carboxamide), ending up with 1-benzyl-1,2,3,4-tetrahydroisoquinolines bearing an N-ethoxycarbonyl residue, which in turn was easily converted directly into an N-methyl group

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• amines 2c, 2d, and 2f, albeit in drastically lower yield (Table 1, entries 3, 4, and 6). Initially, our focus was on testing tertiary amines, as we speculated that the electrophilic iminium species 4a (R1, R2 = alkyl; Scheme 3) would form more easily with stabilizing electron-donating alkyl substituents

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• take part in electrophilic [1][2] and nucleophilic [3][4][5][6] addition reactions onto the acetylene bond leading to various substituted nitriles. Reactions onto both acetylene and nitrile groups are widely used for the construction of various heterocyclic systems [7][8][9][10][11][12][13][14][15

• our work on electrophilic transformations of alkynes [18][19][20], we investigated reactions of 3-arylpropynenitriles under electrophilic activation conditions (see [21] for the chemistry of superelectrophilic species). The goal of this work was to study the reactions of 3-arylpropynenitriles with

• incomplete conversion of the starting compound 1a and a low yield of the target product 2a (<10%). The yields of the compounds 2 were moderate (20–64%) that may be caused by possible transformations of the nitrile group in the electrophilic medium leading to oligomeric material [22]. The reaction proceeded

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• bifunctional pyrrolidine-containing sulfinylureas and thioureas. These catalysts operate via enamine activation of aldehydes and hydrogen-bond activation of the electrophilic component, in this study – nitrostyrenes. These catalysts were effective in the Michael addition of aldehydes to nitroalkenes, affording

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• synthetic utility, we surmised that replacing the aroyl component of the N-phenacyl substituent by electrophilic groups such as esters, amides or nitriles might yield 2,3-dihydro-1H-pyrrolizin-6-ones 13 or their hydroxypyrrole tautomers 13’. Our findings with N-(ethoxycarbonylmethyl)enaminones 14 are

• . Firstly, the E-geometry of reactant 15a is obviously incorrect for the cyclization, which requires the nucleophilic methylene adjacent to the ester to approach close enough to the electrophilic carbonyl group of the enaminone for the intramolecular condensation to occur. It is possible that acid-induced

• reaction in the same solvent gave high yields of pyrrolo[2,1-b]thiazol-6-ones [56]. The former results from reaction between the α-methylene position of the ester and the electrophilic carbonyl component of the enaminone, while the latter arises from nucleophilic attack of the enaminone at the ester’s

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

• state CuI*Ln via rapid ISC. The excited CuI*Ln species has a lifetime to finish the chemical processes. A radical mechanism is proposed in Scheme 4. In path a (a ligand transfer cycle), CuI* is oxidized by an electrophilic reagent (haloalkane) to form CuII and the radical species R• in a single-electron

• )–substrate catalytic cycle Upon the irradiation of LnCuINu, an electron is transferred from the metal center to the ligand, thereby generating the excited state LnCuINu*. The excited state species can be oxidized by the electrophilic reagent (haloalkane, RX) to form the intermediate [LnCuIINu]X. The desired

Direct C(sp³)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

• Siyu Wang,
• Lianyou Zheng,
• Shutao Wang,
• Shulin Ning,
• Zhuoqi Zhang and
• Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

• would be significant in many fields [4][5][6][7]. Although transition-mental-catalyzed allylic substitution reactions employing various nucleophilic or electrophilic allylic precursors have been extensively studied [8][9][10], limited strategies were reported for their application in the C(sp3)–H

• acetamides and acetates catalyzed synergistically by a metal acyclic iridium complex and a chiral Cu(I) complex [19]. Besides transition-metal-catalyzed allylic substitution reactions, Lewis-base-catalyzed allylic functionalizations using Morita−Baylis−Hillman (MBH) adducts as electrophilic allylic

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

• development of efficient methods to access multifunctional ferrocenes has attracted tremendous attention. Conventionally, functionalized ferrocenes were derived via electrophilic aromatic substitution mediated by strong Lewis acids or direct metalation using strong bases, such as alkyllithium reagents [3][9

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

• also found that the aza-annulation could be carried out under iodine-mediated electrophilic annulation reaction conditions to give 5-iodo-3,6-disubstituted pyridines 3 as the major products, occasionally with a small amount of 2-acylated pyrroles 4. The proposed mechanism for the Ag-catalyzed aza

• be carried out at 90 °C in 8 h to provide the 5-sulfenyl-substituted nicotinates 19 efficiently. Based on previous literature and control experiments, the possible mechanism is outlined in Scheme 8. First, the Cu-complex-polarized X−X bond can promote the electrophilic addition onto the alkyne to

• the hydrogenation of dihydropyridinones 32 and a following desulfonylation and aromatization to give pyridine derivatives 33 in moderate to good yield. Synthesis of pyrroles via tandem annulation of 1,3-enynes Recently, great achievements have been made in electrophilic iodocyclization of alkynes for

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• the transformations of these heterocyclic compounds in electrophilic media. The main goals of this work were the synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and the study of their reactions with/without arenes under the conditions of superelectrophilic activation by the Brønsted superacid CF3SO3H

• at very low temperature –70 to –60 °C, that resulted in low to moderate yields of the target acetylene derivatives. Then, electrophilic reactions of 5-acetylenyloxadiazoles 3a–d in different acids were studied. In our recent study on the electrophilic activation of 5-styryl-1,2,4-oxadiazoles 1 [24

• positive charge (0.40–0.47 e) and gives a big contribution into LUMO (16.7–30%), pointing out that this carbon is a reactive electrophilic center by charge and orbital factors. Thus, according our previous data on reactions of 5-styryl-1,2,4-oxadiazoles 1 [24] and results of the DFT calculations for

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

• Michael-initiated ring closure cyclopropanation at the more electrophilic olefin. The α-keto cyclopropyl intermediate 53 was formed in 79% yield with a dr value of >20:1. Reducing the proportion of DMF to 5% with respect to THF in the reaction mixture was hypothesized as the key factor for maximizing the

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• Pd(II) [8][9][10], Ru(II) [11][12][13], Rh(III) [14][15][16], Mn(II) [17][18][19], Au(II/I) [20][21][22], Ag(I) [23][24][25] etc. in both cascade and sequential reactions have been published. Electrophilic Hg(II) salts are important reagents in organic synthesis and there is published literature

• electrophilic addition (Scheme 26). Schwartz et al. developed a new route for the synthesis of exocyclic enol ether 83 and endocyclic enol ether 85 involving a Hg(II)-induced cyclization of acetylenic alcohols 82 and 84, respectively [79]. This work revealed that the regioselectivity of the Hg(II) addition to

• ]. Devan et al. had developed similar types of Hg(TFA)2-mediated cyclizations of allene 116 at low temperature followed by reduction with alkaline NaBH4 to form cyclized product 117 in moderate yield [88]. The reaction was believed to proceed through Hg(II) ion-promoted electrophilic cyclization (Scheme 35

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• -substituted oxindoles; Introduction 3-Monohalooxindole heterocycles are not only present as a characteristic structural motif in numerous biological and medicinal molecules [1][2] but also possess dual nucleophilic and electrophilic character at the C-3 position. Owing to the dual nature at the C-3 position

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• ] (Scheme 10c) described by Jacobsen and co-workers in 2010 and 2014, respectively [50]. In the one hand, while the thiourea unit in catalyst 43 abstracts the bromide in 45 and forms an electrophilic benzhydryl cation, the free amine group activates the aldehyde substrate 46. The resulting enamine can then

• way, the corresponding β-glycosides 79 were almost exclusively obtained (up to 88% yield, up to 98% ee). The reaction was found to proceed stereospecifically with inversion of the anomeric configuration and, therefore, being dependent on the configuration of the electrophilic partner 78. With this

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

• generation of nucleophilic α-amino radicals 2-IV via a photoredox-mediated HAT process. At the same time, the in situ generated nickel(0) species 2-V by a SET process would undergo oxidative addition into aryl bromide 3, resulting in the electrophilic nickel(II)–aryl intermediate 2-VI. The rapid coupling of

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

• ]. The reason behind the C-2 attachment of the boron atom rather than at the C-3 position of the indole ring was explained by McGough et al. [37]. They performed a base-free catalytic I2-assisted indole C–H functionalization (electrophilic borylation) using the N-protected indole 1 and NHC·borane 4a that

• obtaining diaryl sulfides [117]. Selenides Along with the oxygen insertion, Black et al. also performed the oxidative selenium insertion into the C-7 position of highly electrophilic 2-methylindole derivative 184. The dual role of selenium dioxide consists of activation of the C-7 position giving the

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

• 129b via double iodonium-induced electrophilic cyclization. The terphenyl 130 was converted to the diiododibenzo[a,j]anthracene derivative 132 in two steps comprising cyclization and further treatment of intermediate 131 with sulfuric acid [64]. Watanabe and co-workers investigated the oxidative

• . AuCl-catalyzed double cyclization of diiodoethynylterphenyl compounds. Iodonium-induced electrophilic cyclization of terphenyl derivatives. Oxidative photocyclization of 1,3-distyrylbenzene derivatives. Oxidative cyclization of 2,3-diphenylnaphthalenes. Suzuki-Miyaura/isomerization/ring closing

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• electrophilic and nucleophilic α-functionalizations are possible, whereas with the use of α,β-unsaturated aldehydes the β-position is functionalized with nucleophiles and the γ-position with electrophiles. In this sense, Jørgensen and colleagues have developed the first organocatalytic asymmetric Michael

• % ee) (Scheme 10). A catalytic asymmetric β-C−H functionalization of ketones 33 with 4-hydroxycoumarins 1 was developed by Zhu et al. [43]. The enamine, formed via reaction of the aminocatalyst 35 with the ketone, is oxidased by IBX resulting in the electrophilic imine, which in turn undergoes 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

• heteroaromatic electrophilic substitution and a non-radical pathway. An aminomethylation of the heteroaromatic ring with N-methylmorpholine-N-oxide catalyzed by VO(aca)2 reported by Mitchell and co-workers [109], however, was found to undergo with a regioselective outcome incompatible to an electrophilic

• /hemiacetal avoiding undesirable elimination to the enamine, or attack at other electrophilic sites in complex substrates. The presence of a fluorine source like diethylaminosulfur trifluoride (DAST) or the Lewis acid boron trifluoride diethyl etherate (BF3·OEt2) result in the formation of reactive iminium or

• anilines afforded α-aminoalkyl radicals that could be coupled with a wide range of electrophilic partners to afford the products in moderate to good yields. The new reaction was also used in the first step of the total synthesis of a caspase-3 inhibitor (90), and mechanistic investigations showed that O2

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• useful electrophilic or radical fluorinating agents by virtue of their easy handling, efficiency, and selectivity. These non-hygroscopic nature and stability make them easier to handle than nucleophilic fluoride reagents. Potassium fluoride (KF) and naked fluoride anion salts are extremely sensitive to

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

• electron-rich benzylic position, rationalizing the involvement of electrophilic metallonitrene intermediate 18A. Manganese-catalyzed late-stage C–H methylation The incorporation of methyl groups has the potential to manipulate absorption, distribution, metabolism, and excretion (ADME), solubility, and

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

• -triazole-based phenol or alcohol coordinates to the Pd center to form complex 158. Then, the electrophilic palladation of the 1,2,3-triazole ring occurs to achieve Pd(II) intermediate 159. Isocyanide migrates to 159 to obtain the seven‐ or eight‐membered palladium cycle 160. The reductive elimination of