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

• aryl iodides containing electron-donating and electron-withdrawing groups exhibited good to excellent results in the reaction. Notably, the yield of the Click reaction with 2-iodotoluene decreased due to the steric effects. Moreover, the utilization of an efficient heterogeneous catalyst and

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• porphyrin layers compared to the packing of compounds 13 and 13A (Supporting Information File 1, Figure S37). However, these deviations are in line with crystal packing and minor steric effects to be expected for this class of compounds with little to no deviations seen in the bond lengths, angles, and atom

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

• additives at 50 °C and under irradiation with light (Scheme 32). The reaction is compatible with phenyl substituents with high steric hindrance, indicating that steric effects of the aryl moiety in the migrating styrenyl group do not play a major role. In 2018, You and colleagues [19] reported the discovery

Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines

• Geetanjali S. Sontakke,
• Rahul K. Shukla and
• Chandra M. R. Volla

Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42

• inferior yields (Table 1, entries 8–10). Using the optimized reaction conditions, we explored the substrate scope of our developed strategy using quinoline N-oxide (1a) with triazoles 2 having variable functional groups (Scheme 2). We examined the impact of electronic and steric effects of the substituents

• mentioning that when pyridine N-oxide was employed instead of 1a, only traces of the corresponding product were observed even after prolonged reaction time. Subsequently, the substrate scope was evaluated by analyzing electronic and steric effects of substituents present on the quinoline N-oxides 1 (Scheme 3

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• substituents (i.e., in 2f–i, Table 2, entries 1–9). These results also suggest that the reaction is not sensitive to steric effects since no consistent results were obtained comparing the ortho- and para-substituted benzyl groups (see entries 2 vs 3 and 7 vs 8 in Table 2). Beyond benzyl groups, the sodium S

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• increasing water fractions from 0% to 30%, but only a weak ACQ effect upon further increase of water fraction, as compared to H. This is probably due to the steric effects suppressing intermolecular stacking in the aggregates: in the case of H, π–π stacking is favored upon increasing the water fraction

Conformational preferences of fluorine-containing agrochemicals and their implications for lipophilicity prediction

• Daniela Rodrigues Silva,
• Joyce K. Daré and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2020, 16, 2469–2476, doi:10.3762/bjoc.16.200

• on conformation, membrane permeation, pharmacokinetic properties, among other parameters [7]. From a conformational analysis point of view, the fluorine atom presents minimal steric effects; on the other hand, due to its high electronegativity, the C–F bond is highly polarized, which characterizes it

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• %, respectively. In contrast, the fluorine ortho-substituent drastically inhibited the reaction, which is evidently attributed more to electronic than to steric effects. The formation of alternative O-arylated products was ruled out by conducting a NOE NMR experiment with compound 3b as an example. Saturation of

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

• [201], due to the instability of the primary radical (Figure 10). The selective fluorination of C2 over C3 may be rationalized by steric effects (rather than polarity matching), which are reported for quinuclidinium radical cations [203]. A similar selectivity for the most hydridic C(sp3)–H bond was

Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups

• Xiaoyun Hu,
• Jianxin Guo,
• Cui Wang,
• Rui Zhang and
• Victor Borovkov

Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155

• for the enantioselectivity (Table 2, entries 4–6, and 8) except for the sterically demanding tert-butyl group (Table 2, entry 12). Obviously, steric effects in the aromatic aldehydes played a key role for the enantioselectivity of the reaction. To further confirm the importance of two secondary free

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

• . In contrast, the phosphorus analog 29d was obtained in 45% yield, which could be explained by favorable electronic and steric effects of the phosphonate group. In the same work, the authors also evaluated the PKR of CF3-substituted enynes 30. In this case, bicyclic products 31 were formed as mixtures

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

• decomposition of the reaction components (Figure 1). Then, the substrate scope of the transformation was investigated, reacting different benzylic pyridinium salts with N-phenyl-THIQ (1, Scheme 2). Initially, steric effects were investigated using ortho, meta, and para-methylated benzylpyridinium salts. 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

• enantioselectivities remain unaffected. In addition to the impact of steric effects, variations in the alkyl-substituted silicon reagents also negatively impacted the chemical yields. However, again, there was no effect on enantioselectivity. Interestingly, upon replacement of the alkyl groups on the silicon by three

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

Exploring the scope of DBU-promoted amidations of 7-methoxycarbonylpterin

• Anna R. Bockman and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2020, 16, 509–514, doi:10.3762/bjoc.16.46

• amines to be adequately reassessed on their ease of amidation (Table 2). It was found that the reaction was most affected by an α-substitution on the amine (Table 2; products 11–13). This is in agreement with known Taft parameters which show steric effects are more pronounced for an isopropyl group

• insolubility of pterins in most solvents. We have shown that this reaction also benefits in its ease and often rapid reaction times (typically 5–10 min). While this amidation reaction can be hindered by typical steric effects, we have shown these issues are largely overcome in amines with additional hydrogen

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• is dependent on the inductive and/or steric effects of the substituents present on the backbone [75][76]. The α-phosphorus methylene lithiation presents more prospects for the development of modified 1,3,5-triaaza-7-phosphaadamantane (PTA) ligands [77][78]. A chiral center is also introduced adjacent

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• successful with a bromo-substituted substrates 3e and 3f, demonstrating that the methodology was suitable for substrates with the potential for further late-stage modification. Steric effects were also explored with C2-substituted substrate 3i and 3j, and no significant decline in product formation was

Understanding the role of active site residues in CotB2 catalysis using a cluster model

• Keren Raz,
• Ronja Driller,
• Thomas Brück,
• Bernhard Loll and
• Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

• formed interactions with N103, W186, and especially with I181. The relative energy difference between H and I was also similar in the gas phase and in the enzyme model. However, the activation energy was higher by 3.0 kcal/mol in the active site model, possibly due to steric effects. I was stabilized via

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• integrating a spiroamidorhodamine with a BAPTA, whose anticipated switching remains to be proven [27]. Further, interesting approaches are currently being developed on interfacing calmodulin, a messenger protein ionophore, with photochromes [28]. The use of steric effects to decrease binding offers an

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• the close to orthogonal orientation of the anchoring groups induced by steric effects in 2 and 4. As a result, while the LUMO orbital largely extends through the BODIPY unit towards the cyanoacrylic acid anchors in the case of 1 and 3, it is completely confined to the BODIPY-vinylthiophene core in 2

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• ]. The C=C double bonds are in the cyclohexene units range between 1.307–1.316(3) Å and the S=O bonds are between 1.417–1.414(3) Å. The conformation is defined by steric effects, which force a fold of the cyclohexene rings relative to the mean plane through the pyrrolidine group. For both enantiomers

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• expected, due to classical steric effects (syn-1,3-diaxial repulsion). On the other hand, the amine group is usually very sensitive to the solvent effect. In addition, the increase in the halogen size could lead to a shift toward the ae conformer (equatorial halogen). In the studied system, no change was

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

• the secondary 3’-hydroxy functions. Steric effects on the hydrolysis rate are supposed not to be important, because the rate-controlling step of the hydrolysis is suggested to be the unimolecular degradation of the protonated substrate. This releases the stabilized oxocarbenium ion as an intermediate

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• precatalysts can be attributed to electronic and steric effects associated with the adjacent bulky phenyl groups. Keywords: Grubbs-type precatalyst; hemilabile; 1-octene metathesis; pyridinyl-alcoholato ligand; Introduction The alkene metathesis reaction is now well established as a powerful synthetic tool

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• . Nevertheless, complexes 136–138 were more active than 139–142 in the RCM of 7, conducted at 50 °C and none of those catalysts outperformed HGII-SIMes and HGII-SIPr. Analogous results were observed in the RCM of more crowded substrates. The similar behavior of 141 and 142 indicated that steric effects are more