Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• an electron-donating methoxy group on the phenyl substituent. Derivatives with a 3-OTBS side chain, 12c–e, displayed moderate diastereoselectivity, except for the higher diastereoselectivity achieved for 12f (dr 20:1), probably due to steric effects, albeit at the expense of a reduced isolated yield

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• Hammett parameters account only for the electronic effect of substituents, much research has been devoted to develop physical-organic descriptors, which consider steric effects and separate the electronic effect into contributions from resonance and induction, among others [27][77][78][79][80][81]. In

• the change in predictive performance. Using this method, the authors observed that the main contribution towards enantioinduction by CPAs is through steric effects, in line with previous literature. Besides the establishment of experimental data sets, the number of ML data sets based on quantum

• also the structure for which the descriptors are considered. This can either be ensured by expert-knowledge of preselecting relevant structures, for example based on a known mechanism, or by considering information from the entire conformer ensemble. Parallel to the evolution in modelling steric

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• aromatic aldehydes (e.g., 2{1–3}) did not work in the GBB reaction (Figure 4). This result is in accordance with the previous findings [21]. Notably, steric effects were not significant since o,o′-disubstituted aldehydes (e.g., 2{4–6}) displayed usual efficiency. As might be expected from our previous

• performance in the parallel GBB reaction. (Hetero)aromatic aldehydes 2{1–6} illustrating electronic and steric effects on the parallel GBB reaction. Physicochemical properties of the chemical space of 271 Mln. members obtained by virtual GBB reaction (MW – molecular weight; HAcc/HDon – H-bond acceptor/donor

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• both C–F bonds in 17 and 19 enabled an additional σCH→σ*CF interaction, rather than the negligible σCF→σ*CF electron delocalization that would occur if these bonds were vicinally antiperiplanar. As discerned from the decomposition of the full electronic energy into Lewis (e.g., steric effects) and non

• -Lewis (electron delocalization) contributions, 17 and 19 were favored by a delicate equilibrium between weak repulsion and substantial stabilization due to hyperconjugation. Conversely, structures such as 9 and 10 experienced minimal steric effects but were inadequately stabilized by electron

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• reduction. This electrophilic aromatic substitution usually needs harsh reaction conditions, tedious synthetic procedures and sometimes encounters the trouble of separating positional isomers caused by orientation or steric effects of the pre-existed amino group on the aryl moiety. Nevertheless, anilines

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2024, 20, 1278–1285, doi:10.3762/bjoc.20.110

• , displayed a much lower viscosity, indicating that additional steric effects due to the 4-OCF3 substituent play a role for the viscosity of the TAAIL [48][49]. The viscosities of the NTf2 ionic liquids 37–63 at 25 °C are given in Table 2. In general, with increasing alkyl chain lengths we observe an

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• the chromone and at carbon C-4 of the diene. However, in case of a benzyl and a benzyloxy group located at carbon C-4 of the diene, the overall yields were rather low (20%). This might be explained by steric effects. One of the best yields was obtained for the reaction of diene 6a with unsubstituted

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• Ar and CF3 groups can localize the negative charge and also provide steric effects to afford stereoselective cycloaddition products with 3:1 to 6:1 dr. The steric hindrance also prevents products 9 from undergoing a second cycloaddition. The control reactions of methyl ketone or benzaldehydes gave

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• substituents to make little contribution to the HOMO of either 1H or 12 (as shown in calculated molecular orbitals for several examples [14][50][55][59][60]) and so the dependence of these potentials on Y is likely to be due to a combination of inductive effects and perhaps steric effects on the molecular

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• the importance of steric effects [99]. Indeed, while the addition of the nucleophilic α-amino radical to the α-styrenyl position affords the 6-membered ring (kinetic product via intramolecular 6-exo-trig ring closure) [100] the resulting radical is unstabilized, the 7-membered ring (obtained via

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• possessing representative functional groups was employed subsequently to evaluate the reaction scope and limitations (Scheme 3). Under the optimized conditions, alkenes 2b–e with varying steric effects underwent smooth reaction, yielding the corresponding products 3ab–ae in moderate to good yields (56–68

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• isolated in 34% yield indicating that steric effects play a role during the oxidation step. We further wanted to investigate different arenes, but due to the lack of selectivity of the primary benzyl acetates in the Friedel–Crafts step, we were limited to para-substituted arenes, which unfortunately all

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• HFIP. The regioselective amination of benzylic positions in alkylarenes [82] and ethers [83] directed by steric effects was achieved by the development of sterically hindered “bowl-shaped” imide-N-oxyl radical precursors (Scheme 7). The presented example with a sterically hindered N-hydroxyimide

• -active molecules with a substrate are not very well studied and used. The selectivity in organocatalysis by redox-active molecules is controlled mainly by bond energies, redox-potentials, polar effects [157][158], and steric effects. Enantioselective transformations are relatively rare. Borrowing ideas

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• in 39% yield because of steric effects and the electron-withdrawing nature of the substituents on the ‘N’-atom of the imidazole N-oxides at C-3 position (Scheme 1). Also, with the increase in chain length, the decrease in yield of products 4a,b was observed. After analyzing X-ray crystallography data

Ferrocenoyl-adenines: substituent effects on regioselective acylation

• Mateja Toma,
• Gabrijel Zubčić,
• Jasmina Lapić,
• Senka Djaković,
• Davor Šakić and
• Valerije Vrček

Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133

• isomers) is governed by the steric property of the substituent at the N6-position. Steric effects were evaluated by using Charton (empirical) and Sterimol (computational) parameters. The bulky substituents may shield the proximal N7 region of space, which prevents the approach of an electrophile towards

• product in each case. It comes out that electronic properties of the respective purine are not decisive in terms of regioselectivity. Instead, steric effects may govern the N9/N7 ratio in the reaction mixture. Attempts to find a correlation between the N9/N7 ratio and the steric bulk of the C6-substituent

• ., the regioselectivity is governed by the intrinsic nucleophilicity of the N7 position (Table 1). To correlate steric effects in ferrocenoylation reactions of purines to the measured N9/N7 ratio, the Charton (ν) [41][42] and Sterimol steric parameters [43][44][45] for selected substituents were

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• either the 3-, 4-, or 5- position of the α-pyridinealdehyde, and the desired products 3ba–bc were obtained in 32%, 92%, and 82%, respectively, indicating that the reaction is sensitive to steric effects. We then investigated the electronic effects of the α-pyridinealdehyde on the reaction outcome

Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones

• Yara Cristina Marchioro Barbosa,
• Guilherme Caneppele Paveglio,
• Claudio Martin Pereira de Pereira,
• Sidnei Moura,
• Cristiane Storck Schwalm,
• Gleison Antonio Casagrande and
• Lucas Pizzuti

Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110

• seen in the 1H NMR spectrum. This inversion of the regioselectivity can be attributed to electronic and steric effects of the N-substituent but needs additional investigation for full comprehension. When arylhydrazone 1i or 3i, respectively, was subjected to the same reaction conditions in the absence

Continuous flow synthesis of azobenzenes via Baeyer–Mills reaction

• Jan H. Griwatz,
• Anne Kunz and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2022, 18, 781–787, doi:10.3762/bjoc.18.78

• a nitro-substituent. Moreover, some further cases of ortho-substituted anilines were unsuccessful, for which steric effects could serve as an explanation (see Supporting Information File 1 for details). In comparison with published batch syntheses, the herein reported continuous flow synthesis

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• carbanion I that is solvated by the polar solvent. The carbanion I then adds to the carbon (carbocation) of the nitrile oxide, to give the intermediate II. Due to steric effects, the intermediate II undergoes bond rotation to the lowest-energy conformation II-D in which the methyl group is at a close

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• Supporting Information File 1). When 1 equiv of EsY was added into the m-TPEWP5G solution, the resonance signals of EsY were shifted to upfield regions, which was caused by steric effects and electrostatic interactions between the quaternary ammonium groups containing m-TPEWP5 and the negatively charged EsY

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• only exception. When the reactions of bromopropargylic alcohol 1a with phenols 2b–i were carried out in DMF/H2O, dihydroxyketone 8a was isolated as a side product. Next, several experiments were carried out to evaluate the role of the steric effects of the alkyl substituents in bromopropargylic

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• electron-donating or accepting properties of the substituent in this reaction because the methoxy substituent operates as +M donor in the para and ortho-position and as –I acceptor in the meta-position (as well as in the ortho position in a not conjugated conformation). Also, steric effects do not seem to

• have a main impact on the reaction outcome as both examples of ortho- and para-substituted arene derivatives give similar yields. These results show that there is obviously a fine balance between stereoelectronic and steric effects that determines the outcome of the reaction, as has been shown for the

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• steric effects. Anilkumar and co-workers reported an iron-catalyzed Sonogashira coupling of aryl iodides with terminal alkynes in the presence of a catalytic system made up of the greenest solvent, water, in the presence of 10 mol % FeCl3·6H2O and 20 mol % 1,10-phenanthroline as ligand under aerobic