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Search for "steric hindrance" in Full Text gives 532 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

  • Grzegorz Mlostoń,
  • Małgorzata Celeda,
  • Marcin Palusiak,
  • Heinz Heimgartner,
  • Marta Denel-Bobrowska and
  • Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

Graphical Abstract
  • depends on both steric factors in 11 and the electronic structure of the reactive anion 12. In general, growing steric hindrance prefers the S-attack and, very likely, hinders rearrangement leading to thioaminals 9. This hypothesis is supported by the fact that no formation of products 9 is observed with
  • hindered) suggests that the steric hindrance can play an important role in the trapping process. It is worth of emphasizing that thioaminals [33] and dithioacetals [34] constitute important groups of building blocks, which are of interest not only for pharmaceutically oriented studies [35] but also for
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Published 23 Jul 2025

Microwave-enhanced additive-free C–H amination of benzoxazoles catalysed by supported copper

  • Andrei Paraschiv,
  • Valentina Maruzzo,
  • Filippo Pettazzi,
  • Stefano Magliocco,
  • Paolo Inaudi,
  • Daria Brambilla,
  • Gloria Berlier,
  • Giancarlo Cravotto and
  • Katia Martina

Beilstein J. Org. Chem. 2025, 21, 1462–1476, doi:10.3762/bjoc.21.108

Graphical Abstract
  • efficiently, affording good-to-excellent yields. The Boc-protecting group proved to be stable under the reaction conditions, underlining the importance of avoiding the addition of acidic additives. Steric hindrance exerted a moderate influence on the reaction, and branched aliphatic amines yielded the
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Published 15 Jul 2025

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

  • Lidia Zaharieva,
  • Vera Deneva,
  • Fadhil S. Kamounah,
  • Nikolay Vassilev,
  • Ivan Angelov,
  • Michael Pittelkow and
  • Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

Graphical Abstract
  • acceptors is more pronounced. The effect of the amino group is stronger comparing to NMe2 due to the steric hindrance in the latter. Since in 1 the azo group, an acceptor, is placed on position 8, it is also expended to bring additional inherent stabilization of the 1K tautomer. The effect of the
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Published 10 Jul 2025

Oxetanes: formation, reactivity and total syntheses of natural products

  • Peter Gabko,
  • Martin Kalník and
  • Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

Graphical Abstract
  • : aliphatic > allylic > benzylic. In case of trisubstituted C=C bonds, the cyclisation proceeded with retention of configuration, however, higher reaction temperatures were required due to the increased steric hindrance. Competition experiments revealed a preference for 4-exo ring closure over 5-exo, 6-exo
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Published 27 Jun 2025

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

  • Jiangfei Chen,
  • Yi-Lin Qu,
  • Ming Yuan,
  • Xiang-Mei Wu,
  • Heng-Pei Jiang,
  • Ying Fu and
  • Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

Graphical Abstract
  • and alcohols. Substrates with different substituents, including both electron-donating and electron-withdrawing groups, provided satisfactory yields (7a–f). However, steric hindrance significantly influenced the outcome, as ortho-substituted substrates yielded lower amounts (7c). The study also
  • -substituents induced steric hindrance effects that led to lower yields. To gain further insight into the mechanism, several control experiments were performed. The results indicated that an iminoxyl radical is generated as the initiator of the reaction (Scheme 6). Initially, TBHP undergoes homolytic cleavage
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Published 24 Jun 2025

A versatile route towards 6-arylpipecolic acids

  • Erich Gebel,
  • Cornelia Göcke,
  • Carolin Gruner and
  • Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88

Graphical Abstract
  • equatorial position for the phenylacetylene residue and an axial position for the methyl ester (Figure 4b). This arrangement is most likely the reason for neither (2R,6R)-13 nor (2R,6R)-9 displaying a second signal set. The steric hindrance by forcing both bulky residues into an axial position is no longer
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Published 04 Jun 2025

Pd-Catalyzed asymmetric allylic amination with isatin using a P,olefin-type chiral ligand with C–N bond axial chirality

  • Natsume Akimoto,
  • Kaho Takaya,
  • Yoshio Kasashima,
  • Kohei Watanabe,
  • Yasushi Yoshida and
  • Takashi Mino

Beilstein J. Org. Chem. 2025, 21, 1018–1023, doi:10.3762/bjoc.21.83

Graphical Abstract
  • , compound 7 has a primary alkyl group (n-propyl). This difference reduces steric hindrance and lowers the rotational barrier around the carbon–nitrogen bond, increasing the likelihood of racemization. Results and Discussion N-Propyl-N-cinnamoylamide 7 was prepared from phosphine oxide 8 [32] via an SNAr
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Published 23 May 2025

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

  • Chun-Yu Mi,
  • Jia-Yuan Zhai and
  • Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

Graphical Abstract
  • diastereo- and enantioselectivities. The substituent on the enamide could be varied from aryl to tert-butyl groups, though the terminating aryl group still necessitates an electron-rich arene. As was found in their previous work, the steric hindrance of the phenyl or tert-butyl group was supposed to be
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Published 22 May 2025

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

  • Zhiyang Zhang,
  • Jialei Hu,
  • Hanfeng Ding,
  • Li Zhang and
  • Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

Graphical Abstract
  • 4.4:1 mixture of regioisomeric alcohols with the desired isomer being the major component, presumably due to the considerable steric hindrance from the quaternary carbon at C4. However, decagram-scale separation of these two isomers by chromatography proved troublesome. Fortunately, the distinct
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Published 12 May 2025

Recent advances in controllable/divergent synthesis

  • Jilei Cao,
  • Leiyang Bai and
  • Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

Graphical Abstract
  • , oxidative addition of the C–I bond to palladium formed the four-membered aryl–palladium complex Int-5. Steric hindrance from the bulky dppm ligand, combined with slower aryne release (using KF as the fluoride source), attenuated aryne coordination. Under these electron-deficient conditions, CO
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Published 07 May 2025

Recent advances in the electrochemical synthesis of organophosphorus compounds

  • Babak Kaboudin,
  • Milad Behroozi,
  • Sepideh Sadighi and
  • Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

Graphical Abstract
  • the gram-scale preparation of some samples. An electrochemical flow system was used in this method, in which carbon and platinum electrodes were used as the anode and cathode, respectively, at a constant current of 55 mA (Scheme 8). Due to the steric hindrance caused by the tert-butyl group, the
  • solvent. The results showed that potassium iodide is critical in this reaction, and the reaction failed to give a corresponding product without using KI. This reaction was quickly extended to a wide range of substituted indoles. Moreover, despite significant steric hindrance or the presence of a long
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Published 16 Apr 2025

Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

  • Qingqing Jiang,
  • Xinyi Lei,
  • Pan Gao and
  • Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

Graphical Abstract
  • substrates for this transformation. However, due to steric hindrance, ortho-substituted aniline 1s exhibited significantly lower reactivity, resulting in diminished yields of product 3sa. Notably, disubstituted anilines were also compatible with the protocol, furnishing the desired products 3ta–ya in
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Published 09 Apr 2025

Vinylogous functionalization of 4-alkylidene-5-aminopyrazoles with methyl trifluoropyruvates

  • Judit Hostalet-Romero,
  • Laura Carceller-Ferrer,
  • Gonzalo Blay,
  • Amparo Sanz-Marco,
  • José R. Pedro and
  • Carlos Vila

Beilstein J. Org. Chem. 2025, 21, 533–540, doi:10.3762/bjoc.21.41

Graphical Abstract
  • -butyl group is present in the C-3 position of the pyrazole as in the case of substrate 2e, the reaction did not take place, likely due to a considerable increase in steric hindrance. We also attempted to synthesize 4-(alkenyl)-5-aminopyrazoles using an acyclic ketone, such as acetone, but unfortunately
  • the starting material 3ea, prepared from 2-indanone, the corresponding product was not observed, probably due to an increase in steric hindrance. Finally, 4-cyclohexenyl-5-aminopyrazoles bearing different substituents at the N-1 or C-3 position afforded the corresponding trifluoromethyl carbinols 5aba
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Published 10 Mar 2025

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

  • Long K. San,
  • Sebastian Balser,
  • Brian J. Reeves,
  • Tyler T. Clikeman,
  • Yu-Sheng Chen,
  • Steven H. Strauss and
  • Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

Graphical Abstract
  • irradiation [37]. Notably, the apparent absence of the photodimer in the case of 9,10-ANTH(BnF)2 is likely due to the steric hindrance of the bulky perfluorobenzyl groups in the 9- and 10-positions on the ANTH core. Conclusion The perfluorobenzylation of ANTH and ANTH(Br)2 was performed for the first time
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Published 07 Mar 2025

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

  • Rituparna Das and
  • Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

Graphical Abstract
  • the aryl ring size was also an additive by exhibiting steric hindrance towards the attack of the incoming nucleophile [143]. Tanaka et al. also showed the use of the phthalimidoxy functional group at the C-2 position leading to the 1,2-trans glycosides via the formation of six-membered carbenium ion
  • much studied topic in synthetic glycochemistry [162][163][164]. The effects attributed by the remote groups may also be the summative effect of other factors like steric hindrance, conformational hindrance, or other stereoelectronic factors. However, in this article we have tried to show all the
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Published 17 Feb 2025

Red light excitation: illuminating photocatalysis in a new spectrum

  • Lucas Fortier,
  • Corentin Lefebvre and
  • Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

Graphical Abstract
  • hydrogen-atom-transfer mechanisms with a Hantzsch ester 34 as presented in Scheme 12. Moreover, the study has explored the impact of substrate steric hindrance and halogen bond strength on catalytic efficiency, revealing that bromo- and iodo-substrates react more efficiently, while chloro-substrates
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Published 07 Feb 2025

Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

  • Dmitry E. Shybanov,
  • Maxim E. Kukushkin,
  • Eugene V. Babaev,
  • Nikolai V. Zyk and
  • Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

Graphical Abstract
  • participation of the C=C bond. Apparently, the ratio of the adducts of the Diels–Alder (i.e., I) and the hetero-Diels–Alder reaction (i.e., II) was strongly influenced by steric factors; a decreased steric hindrance in the initial CH acid derivatives led to a more selective formation of the structures I. This
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Published 04 Feb 2025

Recent advances in electrochemical copper catalysis for modern organic synthesis

  • Yemin Kim and
  • Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

Graphical Abstract
  • electrochemical oxidation. In contrast, the naphthyl-substituted Schiff base generated the corresponding enantioenriched product 36 through 1,4-addition followed by intramolecular annulation. When 2,6-disubstituted hydroquinone was used as the starting material, 1,6-addition occurred due to steric hindrance
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Published 16 Jan 2025

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

  • Beatriz Dedeiras,
  • Catarina S. Caldeira,
  • José C. Cunha,
  • Clara S. B. Gomes and
  • M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

Graphical Abstract
  • slight decrease observed for 5ac, with chiral (R)-1-((1-phenylethyl)amino)-1,2-benziodoxol-3-(1H)-one (2c), can be attributed to potential steric hindrance induced by the methyl group attached to the benzylic carbon, which may hinder the nucleophile’s access to the electrophilic center of the HIR. The
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Published 19 Dec 2024

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

  • Yang Chen,
  • Jiao He,
  • Hang Lin,
  • Hai-Feng Wang,
  • Ping Hu,
  • Bi-Qin Wang,
  • Ke-Qing Zhao and
  • Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

Graphical Abstract
  • distributed from one side to the other, likely for steric hindrance, thus maximizing the fluoro–arene interactions by superimposing hydrogenated phenyl segments with fluoroarene ones (Figure S34 in Supporting Information File 1). Consequently, the triphenylene core–core distance is 3.83 Å and almost identical
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Published 16 Dec 2024

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

  • Sergio Torres-Oya and
  • Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

Graphical Abstract
  • enantioselectivities (90–99% ee). This result could be attributed to the higher steric hindrance at the carbon atom of the imine. On the other hand, the reaction of 3-isothiocyanatooxindoles 4 and dienimines 9 afforded the cascade cycloadducts 10 in high yields (74–94%) and excellent diastereoselectivities (>20:1 dr
  • -azadienes bearing substituents at the ortho-position were tested, the enantioselectivities decreased, probably due to higher steric hindrance. The mechanism of the reaction is depicted in Scheme 7; firstly, the dual activation of the azadiene and the enol form of the azlactone through hydrogen bonding with
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Published 10 Dec 2024

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

  • Robin Schulte,
  • Dustin Schade,
  • Thomas Paululat,
  • Till J. B. Zähringer,
  • Christoph Kerzig and
  • Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

Graphical Abstract
  • ones. This lack of correlation may indicate that several different factors and processes contribute to different extent to the course of the photoreaction, for example, steric hindrance and resulting torsion angles between the arene unit and norbornadiene, deactivation of the excited state by
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Published 21 Nov 2024
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  • 80 °C. Additionally, that for a single native α-CD molecule proceeded completely at 60 °C within 2.5 h. Thus, the reaction temperature was confirmed as the key to completing the acylation reaction, probably because of the huge steric hindrance of the densely packed hydroxy groups on the [3]rotaxane
  • highly desired. Therefore, we developed a random modification of α-CD via acylation with methacrylic anhydride, which provided roughly one substituent introduction in α-CD (Figure 16A) [87]. In this reaction, owing to the steric hindrance caused by the first introduction of the methacryl group on the
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Published 19 Nov 2024

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

  • Anastasia I. Ershova,
  • Sergey V. Fedoseev,
  • Konstantin V. Lipin,
  • Mikhail Yu. Ievlev,
  • Oleg E. Nasakin and
  • Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

Graphical Abstract
  • rigidity along the C–C bond between the heterocycle and ethene bridge due to the fused cyclic fragment. As a consequence of the additional ring, the fluorescence efficiency increased. At the same time, solid-state emission was observed due to the steric hindrance, which prevented intermolecular
  • only exceptions were compounds 1e and 1f, containing three methoxy groups. In these cases, a blue shift of the absorption band in comparison to the disubstituted derivative 1d was observed, which was apparently caused by a partial planarity violation due to steric hindrance. In DMSO, the absorption
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Published 19 Nov 2024

gem-Difluorovinyl and trifluorovinyl Michael acceptors in the synthesis of α,β-unsaturated fluorinated and nonfluorinated amides

  • Monika Bilska-Markowska,
  • Marcin Kaźmierczak,
  • Wojciech Jankowski and
  • Marcin Hoffmann

Beilstein J. Org. Chem. 2024, 20, 2946–2953, doi:10.3762/bjoc.20.247

Graphical Abstract
  • methods by the observed coupling constants J ≈ 6 Hz between vinylic fluorine atoms [41]. Due to the steric hindrance, these compounds did not serve as good Michael acceptors for the next step. Only elimination products 14a–d were obtained from trifluorinated amides 2a–d, showing good yields (Scheme 5). We
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Published 15 Nov 2024
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