Nucleophilic functionalization of thianthrenium salts under basic conditions

• Xinting Fan,
• Duo Zhang,
• Xiangchuan Xiu,
• Bin Xu,
• Yu Yuan,
• Feng Chen and
• Pan Gao

Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26

• the resulting products (3ah–aj) can also be obtained with high efficiency. This underscores the viability of integrating this metal-free thioetherification method with other traditional cross-coupling reactions. Sterically hindered ortho-disubstituted thiophenol 2k is also compatible with this

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• DMF. The reaction was performed at 130 °C, as we believed that high temperature will promote the cyclization of the sterically hindered intermediate 3a, but no DBDAP was achieved under these conditions (entry 1, Table 3). Next, Pd(OAc)2 was employed under ligand-free conditions, but again the desired

Copper-promoted C5-selective bromination of 8-aminoquinoline amides with alkyl bromides

• Changdong Shao,
• Chen Ma,
• Li Li,
• Jingyi Liu,
• Yanan Shen,
• Chen Chen,
• Qionglin Yang,
• Tianyi Xu,
• Zhengsong Hu,
• Yuhe Kan and
• Tingting Zhang

Beilstein J. Org. Chem. 2024, 20, 155–161, doi:10.3762/bjoc.20.14

• were obtained in high yields (92‒99%), which demonstrated the practical value of this methodology. Moreover, the reaction showed a good tolerance to sterically hindered substrates like trimethylbenzamide, affording the corresponding brominated product in 70% yield (3la). Also the substrate derived from

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• , the racemization was observed at 80 °C. Torres et al. performed detailed theoretical calculations and showed that the racemization observed in 59 and 60 is caused by triplet-state photogeneration, which leads to the rotation around the sterically hindered buta-1,3-diene chiral axis [132]. In fact, the

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• sterically hindered tertiary carboxylic acids were unfortunately not compatible with the reaction conditions. The structures of products 3a and 3s were unambiguously confirmed by single-crystal X-ray diffraction. Notably, the reaction of 1a could be easily scaled up to 1.0 mmol scale, affording 3a in a

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• –l) were easily and readily oxidized selectively and with good functional group tolerance. A slightly slower conversion was observed for more sterically hindered sulfides (2b–d). For the substrates where kinetics was slower (e.g., sulfides 2m and 2n which are lacking an aromatic moiety), there is the

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• with electron‐donating groups (i.e., OMe, Me) reacted much faster than aniline and furnished the pyrroles in excellent yields. In addition, the reaction of more sterically hindered aniline with 2,5-dimethoxytetrahydrofuran gave moderate yields and less sterically hindered aniline gave good yields. This

• , reactions of sterically hindered anilines with 2,5-dimethoxytetrahydrofuran give moderate yields, and reactions with less sterically hindered anilines give good yields of products. The Clauson–Kaas method for the synthesis of pyrroles has a wide range of applications, including the synthesis of various

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• sterically hindered arylboronic acids. Herein, we report an improved version of this palladium-catalyzed enantioselective three-component reactions using aryltrifluoroborates as replacement of the arylboronic acid building block (Scheme 1d). The broader scope of this 2nd generation protocol is exploiting a

• enantiomeric ratio of 87:13 (compared to 68% and an enantiomeric ratio of 60:40 with the boronic acid). As in the case of arylboronic acids, reactions with a sterically hindered ortho-substituted trifluoroborate furnished the arylglycine product in almost racemic form. Unfortunately, reactions with

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• yield proved to be good to excellent and sterically hindered aryl rings were tolerated. This method was applied by Huang et al. [74] to prepare a series of fluorescent compounds in excellent yield. Copper- and nickel-catalysed arylation were reported as alternatives to the Pd-catalysed arylation of 1a

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• electron-rich salt 5al was obtained in 75% yield using modified reaction conditions B. The harsher conditions were probably required due to a sterically hindered rotation of the benzimidazole moiety in the plane of the iodophenyl, which could also be observed in two rotamers of the starting iodoarene 4al

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

• János Máté Orosz,
• Dóra Ujj,
• Petr Kasal,
• Gábor Benkovics and
• Erika Bálint

Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25

• pure monofunctionalized CDs. Alternative approaches use sterically hindered reagents, preventing the approach of the second molecule of the reagent to provide higher yields for the monosubstituted compounds [4]. The three different hydroxy groups on the glucose subunits offer three different sites on

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

• Benedikt Kolb,
• Daniela Silva dos Santos,
• Sanja Krause,
• Anna Zens and
• Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

• ) yielded 43% of the desired product 27an (Table 4, entry 14) and even the sterically hindered pivaloyl chloride (26p) gave 32% of dienone 27ap (Table 4, entry 16). Due to these promising results, we tested the combination of phenylenyne 25a with acetyl chloride (22), which however provided 32% of the

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• alcohol on the A ring in 75% yield. The C3 epimer was also obtained in 4% yield and confirmed by X-ray diffraction. Hydrogenation of the sterically hindered C1–C2 alkene was accomplished using a combination of Mn(dpm)3 and Ph(iPrO)SiH2, providing grayanotoxin III in 51% yield. The authors also achieved

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

• -hydroxylation of lactams under phase-transfer organocatalysis conditions employing a chiral quaternary ammonium ion salt. Selective CH-oxidation of methylarenes to aldehydes or carboxylic acids. An example of the regioselective CH-amination by a sterically hindered imide-N-oxyl radical precursor. CH-amination

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• ] and provides insights into the biosynthesis pathways of these peptides [14]. However, the biosynthetic gene clusters of compounds 1–4 remain unidentified. Therefore, the least sterically hindered amine, namely the amino group of glycine, was selected as a nucleophile of the cyclization reaction in

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• electron-donating or electron-withdrawing groups on the phenyl rings (R2) afforded the corresponding 2-arylbenzoxazoles 8b–g in good to excellent yields (79–99%). The nature of substituents on the benzene rings of the thioamides did not significantly affect the reaction outcome. Sterically hindered

• tosyl group instead of the diamine 14, and the corresponding product 16c was obtained. The reaction of 15 with various thioamides 2 bearing electron-donating or electron-withdrawing groups on the phenyl rings, sterically hindered aryl groups, heteroaryl groups, and alkyl groups also proceeded

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• -methylphenol (DTBMP)), trifluoroacetic acid (TFA), and 4-methylbenzenesulfonic acid (TsOH) as the proton donors. The results indicated that the less bulky methanol, more bulky DTBMP, more sterically hindered and acidic TsOH show certain regio- and stereoselectivities, which also depended upon the steric

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• prochiral cyclopropene 2j from the less sterically hindered side. This is consistent with previous experiments in which 3-substituted-1,2-diphenylcyclopropenes were utilized as dipolarophiles. Regretfully, neither methyl 1-methylcycloprop-2-enecarboxylate (2k) [37] nor 3-methyl-1,2,3-triphenylcycloprop-1

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• formation of a single diastereomer at the cyclopropanation step can be explained by the preferred approach of carbene A from the least sterically hindered side of indene C and the π-stacking interaction of the aromatic fragment of indene and the benzylidene substituent of the carbene. The conversion of

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• group forming a six-membered ring system that upon reaction with 7-chloro-4-hydrazinylquinoline formed 5-aminopyrazoles 5a,l–o. Here, a nucleophilic attack of the NH2 group of the arylhydrazine on the C3 position of the butadiene chain is observed due to the sterically hindered rigidized six-membered

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• deposition process. However, when compared with the D–A–D counterpart, the Td of 1 is much lower (by 111 °C) than that of POZ-DBPHZ (453 °C) [17]. These data would support that the increase in the sterically hindered donors in emitting molecule suppress intermolecular contact to enhance the thermal stability

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

• leading to intermediate A, nucleophilic attack of phenolate at the less sterically hindered carbon of the above zwitterion A and subsequent protonation of anion B (Scheme 8). Based on these plausible mechanisms for the formation of phenoxyketones, it can be assumed that a decline of the Cs+ concentration

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

• . Unfortunately, the latter was not available on preparative scale (see above) so that this aspect could not be clarified with control experiments. At the same time, the coupling reaction may also be sterically hindered by the 3-methyl group of the norbornadiene 2b, which is in agreement with the low yields of

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

• conditions [13]. This system is applicable to sterically hindered aryl iodides or substituted aryl iodides with terminal arylalkynes (Scheme 2). K3PO4 was the effective base for the reaction of 4-iodoacetophenone with phenylacetylene. Ligands such as DABCO and trans-1,2-diaminocyclohexane were also tested