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

• possible in a pseudo-seven-component reaction starting from 1,4-diiodobenzene. The product 108c showed strong solvatochromism. The synthesis of pyrazoles from terminal alkynes, acyl chlorides, and hydrazines [124][126] can be extended by subsequent halogenation at position 4 with N-halosuccinimide 109 (X

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• for the halogenation of organic substrates. For example, Banerjee and co-workers reported the mono-, di-, and trihalogenation of aromatics by controlling the stoichiometry of the N-halosuccinimide (NXS) and PEG-400 as the grinding auxiliary in a mechanical grinder (Scheme 1a) [3]. N-Halosuccinimides

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• ][57]. Herein, we report a sustainable and facile aromatic (mono-, di-, and tri-) halogenation protocol by controlling the stoichiometry of the N-halosuccinimide and PEG-400 as the grinding auxiliary in an electrical grinder (Scheme 2). Results and Discussion At the outset, the optimization of the

• potential application of the new protocol in large-scale synthesis with adequate grinding equipment. Lastly, a comparative study of available methods for N-halosuccinimide-aided electrophilic halogenations with our auto-grinding protocol was conducted (Table S2 in Supporting Information File 1). It

Mechanochemical halogenation of unsymmetrically substituted azobenzenes

• Dajana Barišić,
• Mario Pajić,
• Ivan Halasz,
• Darko Babić and
• Manda Ćurić

Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69

• ; N-halosuccinimide; palladium(II); Introduction Electrophilic aromatic substitution [1][2][3] and ligand-directed transition-metal-catalyzed reactions [4][5][6][7][8] are among the most widely used synthetic approaches for the preparation of halogenated arenes. They are important precursors in cross

• ][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], their application in the synthesis of halogenated arenes is still scarce. In 2015, Bolm and Hernandez reported the halogenation of 2-phenylpyridine in a ball mill using [Cp*RhCl2]2 in combination with AgSbF6 as catalyst and N

• -halosuccinimide (NXS, X = Br, I) as halogen source [47]. Two years later in 2017, Eslami's group applied a ball-milling method to synthesize aryl bromides and α-bromoketones with N-bromosuccinimide (NBS) and MCM-41-SO3H catalyst and no liquid additives [48]. In 2018, Wang and co-workers developed the ball-milling

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

• 48 with organic azides was studied by Smirnov et al. The alkynes 48 were subjected to the action of MeMgCl in THF and then, the desired aryl azides were added into the solution, followed by the addition of N-halosuccinimide to give chloro-, bromo-, and iodotriazoles 50 (Scheme 17) [47]. It was found

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• radical C(sp3)−H halogenation at the benzylic and allylic position using N-halosuccinimide with azobisisobutyronitrile or benzoyl peroxide as a radical initiator is known as the Wohl–Ziegler bromination reaction, which requires heating, acidic/basic conditions, and/or UV irradiation (Scheme 1a) [17][18

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• )-15b were formed as single products, without any regio- or stereoselectivity issues (Scheme 8). However, repeated N-halosuccinimide addition was necessary, and the yield of the bromofluorination reaction was still mediocre. The stereochemistry of the products (rac)-15a and (rac)-15b was determined by

Palladium-catalyzed ortho-halogenations of acetanilides with N-halosuccinimides via direct sp² C–H bond activation in ball mills

• Zi Liu,
• Hui Xu and
• Guan-Wu Wang

Beilstein J. Org. Chem. 2018, 14, 430–435, doi:10.3762/bjoc.14.31

• corresponding N-halosuccinimides. Keywords: acetanilide; ball milling; C–H activation; halogenation; mechanochemistry; N-halosuccinimide; palladium catalysis; Introduction Aryl halides have been widely utilized in organic syntheses, which give access to a range of complex natural products [1][2]. However

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• agent oxone (Scheme 24) [97]. Carbon–carbon double (C=C) and triple (C≡C) bonds-containing compounds are also reported to undergo dihalogenation reactions under mechanochemical conditions. In 2014, Mal and co-workers reported a mild aryl halogenation reaction using respective N-halosuccinimide (NXS

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• added DBU (1.4 mmol) and stirring was continued at 0 °C for 5 min before the N-halosuccinimide (1.1 mmol, NBS or NCS or NIS) of choice was added. There was an immediate color change from yellow to orange or red, and the conversion of EDA was completed in less than 5 min as judged by TLC analysis. After

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• adjacent to oxygen via an N-halosuccinimide- (NCS or NBS)-assisted copper-catalyzed process. As shown in Scheme 2, both cyclic and acyclic compounds 6 containing a benzylic C–H bond could be readily converted to N-alkylamides 8 or sulfonamides 9 via this much milder catalytic method. In addition, this

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• be acquired. In this regard, a synthetic approach allowing the tunable synthesis of mono- and dihalogenated products was highly desirable. Recently, Han and co-workers [36] achieved successfully this kind of tunable reaction via a CuX-mediated aryl C–H halogenation with the assistance of NXS (N

• -halosuccinimide, X = Cl or Br). The application of different acids which participated in the in situ formation of acyl hypohalites enabled the selective generation of products 2 and 7 (Scheme 5). Notably, the C–H iodinated product of type 2 was also observed as key intermediate in the copper-catalyzed pyridinyl

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• introduced by our group, both employing an N-halosuccinimide as the halogen source in combination with either the amidine base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or sodium hydride (NaH). In these reports, the obtained α-halodiazoacetates and α-halodiazophosphonates were successfully applied in