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

• -workers reported a one-pot synthesis of substituted anthracenes 37 from o-tolualdehyde 34 and aryl iodides 35 via a palladium-catalyzed C–H arylation with a silver oxidant (Scheme 8) [42]. During optimization studies, the authors noted that steric and electronic effects strongly affected the cyclization

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• observed > 99% N-1 regioselectivity for 3-carboxymethyl, 3-tert-butyl, 3-COMe, and 3-carboxamide indazoles. Further extension of this optimized (NaH in THF) protocol to various C-3, -4, -5, -6, and -7 substituted indazoles has highlighted the impact of steric and electronic effects on N-1/N-2 regioisomeric

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

• them in view of their great significance in organic synthesis. In 2018, Miyake and colleagues [50] found a protocol for the preparation of (Z)-2-iodovinyl phenyl ether 168 by utilizing ethynylbenziodoxol(on)e (EBX) 167 and phenol derivative 166 (Scheme 59). Due to the lack of significant electronic

• effects of phenol, a variety of phenols, including electron-donor and electron-withdrawing groups, were been converted into corresponding 2-iodovinyl phenyl ethers in moderate to excellent yield with high regio- and stereoselectivities. According to the analysis of the mechanism (Scheme 60), a molecule of

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• by nucleophiles. As is the case for the nucleophilic opening of epoxides, the regiochemistry of this process is often controlled very effectively by the combined steric and electronic effects of the substituents attached to the ring, with a spectrum of SN1 and SN2-like reactivity possible. Several

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• influenced by the electronic effects induced by the substituents of the aniline unit (Table 1). Detailed information about characterization data for compounds 2a–l is given in Supporting Information File 1. X-ray crystallographic data In order to bring evidence of the geometry and arrangement of the

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• , 2,4,6-triisopropylphenylacetylene, and para-substituted 4-R-phenylacetylenes (R = NMe2, OMe, CF3)) with electronically variable benzohydrazides (4-R = NMe2, H, NO2) were tested, to cover a range of steric and electronic effects. Most hydrohydrazidation reactions showed nearly quantitative product

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• the intramolecular version, the fluorine atom or fluorinated group can also form a part of the linker. The reaction yields are dependent on the degree of substitution, bulkiness, and electronic effects of the substituents of both the alkyne and alkene moieties. In general, electron-deficient alkynes

• groups of comparable steric demand at both ends of the alkyne, electronic effects come into play. Here, the more electron-rich substituent occupies the α position, and the more electron-poor the β position (Scheme 4). This selectivity could be rationalized by the insertion of the olefin into the weakest

• Co–C bond. These electronic effects have been shown to be less important than steric ones, and are often overcome by the latter. Regarding the stereochemistry, exo-products are almost exclusively obtained for norbornene and norbornadiene. Many deviations from the classic reaction conditions have been

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• hydroborations proceeded with the exclusive formation of isoxazolidines with a hydroxy group in the C-4 position. We assume that the excellent regioselectivity is unambiguously caused by electronic effects since the endocyclic oxygen atom donates electrons to the C=C double bond, developing a negative partial

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

• ring, and the yield of the target product weakly depends on the electronic effects of substituents in this ring (products 70a–d). Good yields were obtained even with substrates having inert non-benzyl C(sp3)–H bonds (products 70f–h). It is important to note that products with two substituents in the α

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

• carboxylates. Aminyl and aminium radical generation The prevalent strategy for accessing aminium radicals is SET oxidations. The efficiency of this approach is closely related to the stabilization of the generated radical on the substrate (delocalization, electronic effects) or through a strain release ring

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• substituents had a negative effect on the efficiency of the transformation, independently of their electronic effects (Scheme 3, 21–25). Still, halides, nitriles, and ester substituents were tolerated, giving a possible handle for further manipulation. However, the presence of a nitro group impeded the

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• steps: first, borocupration followed by an electrophilic cyanation, and finally, a second borocupration. It was discovered that steric factors determine the site of the first borocupration, while electronic effects are dominant in the second addition of boron (Scheme 61) [114]. The selective

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• Scheme 3), after having identified the optimized conditions for benzaldehyde synthesis from iodobenzene. The results showed that electronic effects had little impact on the reaction. Both, substrates with electron-withdrawing or electron-donating groups afforded similar yields. However, steric effects

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• role of the electronic effects of the nitrogen atoms on this cyclic substrate, and then we revised our synthetic strategy by a) tethering an alkene functional group on the aromatic ring and b) then conducting the oxidation of the benzylic group to afford the aldehyde product. Towards this end, we

Copper-catalyzed remote C–H arylation of polycyclic aromatic hydrocarbons (PAHs)

• Anping Luo,
• Min Zhang,
• Zhangyi Fu,
• Jingbo Lan,
• Di Wu and
• Jingsong You

Beilstein J. Org. Chem. 2020, 16, 530–536, doi:10.3762/bjoc.16.49

• electronic effects and steric hindrances. Arylating reagents with ortho-substituents led to slightly reduced yields (Scheme 2, 3f and 3i). Aryliodonium salts containing halogen substituents, especially bromo and iodo atoms, could afford the desired products in moderate to good yields (Scheme 2, 3j–n), making

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• hexaborylated HBC 1. The structure of thus-obtained 1 was confirmed by X-ray crystallography, and the electronic effects of the boryl groups were investigated through optoelectronic measurements and density functional theory (DFT) calculations. Results and Discussion We have examined the conditions for C–H

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• function as 2π, 4π, 6π or 10π components (Table 2). This functionality is dependent both on the other reactant partner, and the electronic effects of the fulvene substituents [96][97][98][99][153][156]. As an example, in [4 + 2] cycloadditions, fulvenes will participate as 4π components (diene), provided

A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes

• Joza Schmitt and
• Scott T. Handy

Beilstein J. Org. Chem. 2019, 15, 1781–1785, doi:10.3762/bjoc.15.171

• expected due to the lack of direct conjugation with the carbonyl as well as the only modest electronic effects of alkyl, chlorine, and bromine. In general, the substituent effects are all fairly modest and result in fairly moderate changes in the extinction coefficient (although hydroxy substitution does

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Anomeric sugar boronic acid analogues as potential agents for boron neutron capture therapy

• Daniela Imperio,
• Erika Del Grosso,
• Silvia Fallarini,
• Grazia Lombardi and
• Luigi Panza

Beilstein J. Org. Chem. 2019, 15, 1355–1359, doi:10.3762/bjoc.15.135

• the arabino-configurated epimer from the reaction mixture, which, if present, may therefore be formed in a very small amount. As expected, no regioisomer was detected, due to the contribution of both steric and electronic effects on the hydroboration at C-1 [7]. In order to explain the

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• heterocyclic ring Boruah and co-workers extended the same approach to different steroidal starting materials and varied the substituents in the arylaldehyde component to investigate the steric and electronic effects on the yields of the steroid-fused pyrimidine products [43]. Thus, the yield increases when the

• groups like CH3 and OMe does only partially. Both steric and electronic effects can be explained from the reactivity of the diimine intermediate. An electron-withdrawing group promotes the nucleophilic attack of the ketoimine N by increasing the partially positive charge of the imine C. In general

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• substituent) reduces the potential diversity of the chemical environment of the catalytic centre [18][19][20][21]. In our opinion, replacing the oxygen atom by the nitrogen atom in the lower part of the catalyst would enhance the variability for both steric and electronic effects of the substituents (Figure 1

Study on the regioselectivity of the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide

• Pedro N. Batalha,
• Luana da S. M. Forezi,
• Maria Clara R. Freitas,
• Nathalia M. de C. Tolentino,
• Ednilsom Orestes,
• José Walkimar de M. Carneiro,
• Fernanda da C. S. Boechat and
• Maria Cecília B. V. de Souza

Beilstein J. Org. Chem. 2019, 15, 388–400, doi:10.3762/bjoc.15.35

• for the deprotonation reaction using potassium carbonate as a base. These results are in agreement with the analysis of the stability of the conjugate bases due to structural electronic effects. The oxoquinoline conjugate base presents a great stability, since it promotes a greater dispersion of the

• verification is, for example, justified by the analysis of the electronic effects, as shown in the Scheme 5. Precisely because it is more unstable, the carboxamide conjugate base is a more reactive nucleophile and, therefore, associated with a lower energy barrier for the nucleophilic substitution reaction

Synthesis, biophysical properties, and RNase H activity of 6’-difluoro[4.3.0]bicyclo-DNA

• Sibylle Frei,
• Adam K. Katolik and
• Christian J. Leumann

Beilstein J. Org. Chem. 2019, 15, 79–88, doi:10.3762/bjoc.15.9

• . The reason for the stabilization is an increased strength of the Watson–Crick base pairing and base stacking interactions due to the electronic effects of the axially oriented 2’-fluorine atom [11][12]. Additionally, FC–H···O hydrogen bonds between the 2’-fluorine and the 4’-oxygen or 5’-oxygen of the