Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• crystallised in the monoclinic space group P21 with R1 = 0.0285 clearly showing the expected (R)-configuration with a Flack parameter of −0.07(6). Starting from monomethylaniline derivative 7, the synthesis of the final building block was finalised by chlorination [20], Alloc protection and saponification [21

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• the chlorination reactions on the synthetic path to Cl2B and Me2B, chlorine gas was generated by reacting MnO₂ with HCl and then passed through a stirred suspension of the pyrazolinone. In the case of Me4B, trichloroisocyanuric acid (TCICA) was used as the chlorinating agent as a safer alternative to

• . Experimental Synthesis The studied bimanes were synthesized following the approach reported by Kosower and co-workers [17][19], and an alternative chlorination method developed by Neogi et al. [31]. The synthetic details can be found in Supporting Information File 1. Compounds were crystallized from a MeOH–DCM

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

• the extremes of SN1 and SN2 pathway by employing the effect of counter ions, showing close resemblance with the SNi mechanism [41], conforming to the famous Winstein’s ion-pair theory [42] and draws analogy with chlorination of alcohols by thionyl chloride [43]. Incorporating the role of counter ion

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

• oxidation. C–X Bond formation Cu-catalyzed electrochemical reactions have been developed for the formation of C–C, C–N, and C–X bonds. For instance, in 2013, the Kakiuchi group reported Cu-catalyzed electrochemical chlorination of 1,3-dicarbonyl compounds (Figure 13) [63]. Typical chlorination reactions are

• anodic oxidation of chloride ions, thus replacing stoichiometric chemical oxidants. This catalytic electrochemical chlorination method is suitable for β-ketoesters 68 with electron-withdrawing or electron-donating groups on aryl substituents, as well as for β-diketone, and β-ketoamides. In 2020, Fang

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

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

• oxidative chlorination with aqueous chlorine [30], or treatment with toxic sulfur dioxide. Thus, we envisaged to further investigate BBX reactivity to address the S–N-bond formation, as an alternative method towards sulfur-containing compounds [22]. Results and Discussion We initiated our study by extending

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• derivatives, were synthesized using two reaction sequences (Table 1). The first sequence involved the chloroformylation of isoxazolones 3 to 5-chloroisoxazole-4-carbaldehydes 4 by POCl3/DMF [20][21][22][23], followed by radical chlorination of 4 with SO2Cl2/AIBN [24]. The alternative route to acid chlorides 1

• that chromatography was not required to isolate the products. At the same time, compound 4i proved to be inactive under the used chlorination conditions, compounds 4g,h underwent partial hydrodebromination in the aryl substituent in the same step, while compound 4j yielded a product with difficult to

Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

• Jón Atiba Buldt,
• Wang-Yeuk Kong,
• Yannick Kraemer,
• Masiel M. Belsuzarri,
• Ansh Hiten Patel,
• James C. Fettinger,
• Dean J. Tantillo and
• Cody Ross Pitts

Beilstein J. Org. Chem. 2024, 20, 3134–3143, doi:10.3762/bjoc.20.259

• ). Addition of a CF3SF4 radical to 1 affords INT4, which can either abstract a Cl atom from CF3SF4Cl via TS5 to make 5 or add to another equiv of 1 via TS6 to access INT5. As anticipated, chlorination of the radical is thermodynamically favored over addition to 1 (ΔΔG = −10.7 kcal/mol). It is also predicted

• here that the free energy of activation is lower for chlorination, albeit only by 0.4 kcal/mol. This is consistent with the notion that the kinetic preference can be overcome by increasing the concentration of 1 relative to CF3SF4Cl. In the second product-determining step, Cl atom abstraction by INT5

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• agrochemicals has been shown to greatly increase the potency of a compound [45][46] and can be considered a bioisostere for a methyl group. Chlorination through HVI approaches provides a safe and mild approach to chlorinated cyclic compounds. Nitrogen nucleophiles Intramolecular chlorocyclisation promoted by

• support for the former pathway (Scheme 39). In 2023, Chai, Jiang, Zhu and co-workers included the oxybromination of alkenes to form brominated dihydro-[1,3]-oxazines 76 and 2-oxazoline 77 derivative (Scheme 40) [6][49], alongside their chlorination examples. Optimized reaction conditions were developed

C–H Trifluoromethylthiolation of aldehyde hydrazones

• Victor Levet,
• Balu Ramesh,
• Congyang Wang and
• Tatiana Besset

Beilstein J. Org. Chem. 2024, 20, 2883–2890, doi:10.3762/bjoc.20.242

• corresponding sulfur-containing heteroarenes, only a few methods have been developed (Scheme 1). In 1988, Lee and co-workers reported the synthesis of SR-containing hydrazones in a two-step process (chlorination [65] then reaction with thiols) from readily available aldehyde-derived hydrazones [66]. Wang et al

• aldehyde hydrazones using sodium sulfinates. These seminal works brought interesting proofs of concept for the synthesis of SR-containing hydrazones. Inspired by these previous works and taking benefit from our in-home expertise to forge N–SCF3 bond (after chlorination/anion metathesis with AgSCF3 from the

• Information File 1) [75]. Different reagents for the bromination or chlorination were also evaluated (Table 1, entries 1–3) and NBS was the most efficient one (Table 1, entry 1). With the best reaction conditions in hand, the nature of the hydrazone part was first investigated (Scheme 2). Under standard

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• agrochemical and pharmaceutical chemistry. In 2019, Jiao and colleagues reported that 1,2-dichloroethane (DCE) could be used as a chlorination reagent for the production of (hetero)aryl chlorides and vinyl chlorides [21]. The reactions were carried out in an undivided cell containing a mixture of DCE in

• products were obtained in good yields (51–81%). The reaction involves the catalytic dehydrochlorination of DCE at the cathode, simultaneously with anodic oxidative aromatic chlorination using cathodically released HCl as the chloride source (Scheme 13). Additionally, the Lei group demonstrated a double

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

• 130 through chlorination and Stephens–Castro coupling [148]. With 1,4-dioxane as a solvent, chlorination yields could be increased by activation of oxalyl chloride to give glyoxyl chlorides 133. The resulting ynediones 134 were cyclized in a consecutive three-component fashion with Boc-hydrazine to

• with electrophiles, such as deuteration or electrophilic chlorination using N-chlorosuccinimide, in this consecutive three-component synthesis to give persubstituted pyrazoles 165 (Scheme 55) [162]. (3 + 2)-Cycloaddition – C2 building blocks as substrates 1,3-Dipolar cycloadditions are important

Divergent role of PIDA and PIFA in the AlX₃ (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

• Kevin A. Juárez-Ornelas,
• Manuel Solís-Hernández,
• Pedro Navarro-Santos,
• J. Oscar C. Jiménez-Halla and
• César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

• Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Avenida Francisco J. Múgica S/N 58030, Morelia, Michoacán, México 10.3762/bjoc.20.141 Abstract The reaction mechanism for the chlorination and bromination of 2-naphthol with PIDA or PIFA and AlX3 (X = Cl, Br), previously

• reported by our group, was elucidated via quantum chemical calculations using density functional theory. The chlorination mechanism using PIFA and AlCl3 demonstrated a better experimental and theoretical yield compared to using PIDA. Additionally, the lowest-energy chlorinating species was characterized by

• halogenation via PhIX2. Keywords: aromatic bromination; aromatic chlorination; density functional theory (DFT); hypervalent iodine; iodine(III); Introduction Hypervalent iodine(III) reagents have gained attention as strong oxidants with a low toxicity [1][2][3][4][5][6][7][8] and due to the ability to mimic

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• HAT reagent. Difluorination could be achieved using excess fluoride and HAT reagent. Other nucleophiles were amenable to the reaction conditions, allowing various benzylic functionalisation reactions, including acetoxylation and chlorination. In 2023, Hamashima and co-workers disclosed an analogous

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• ]octane ring-system via the chlorosulfite intermediate. Analogous allylic alcohols with endocyclic and exocyclic unsaturations underwent chlorination without rearrangement due to formation of allylic cations. The rearrangement was also demonstrated using Appel conditions, which gave similar results via

• Diels–Alder adducts of 1, and similar results on the effect of configuration were observed [21]. During some recent attempts at the chlorination of the π-stacking chiral auxiliary 10a using SOCl2 [9], we observed the migration of O8 resulting in the formation of anomeric chlorides analogous to the

• ]. The unsubstituted derivative 11b was difficult to isolate in good yields as multiple products were formed giving complex reaction mixtures. The product 11b was consistently contaminated with a second inseparable product tentatively assigned as 14, which is the expected product of chlorination without

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• hydrochlorination. Silica gel-promoted hydrochlorination of alkenes with hydrochloric acid. Hydrochlorination with hydrochloric acid promoted by acetic acid or iron trichloride. Carreira’s first report on radical hydrochlorinations of alkenes. Radical “hydrogenation” of alkenes; competing chlorination reactions

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• -workers, it was found that in chlorination reactions, activation of alkenes is not driven by the electrophilicity of the reagent being attacked by an alkene, but instead depends on nucleophile assistance: the alkene becomes more nucleophilic upon interaction with the pendant attacking nucleophile [81]. In

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• (pathway b), while nucleophilic attack at C-14 of intermediate IV by a chloride could generate compound 5 (pathway a). In addition, compound 5 might also be derived from intermediate IV by cleavage of the ester bond at C-2 to form the intermediate VI [15], followed by chlorination (pathway c). Compounds 1

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• , sodium phenolate and thiophenolate salts give rise to products 157 and 158, respectively, while the chlorination product 159 was obtained upon the addition of tetrabutylammonium chloride (Scheme 31C). Mechanisms under electrochemical activation The electrochemical activation of NHPI esters provides

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

• , the synthesis of important C5-halogenated products gained particular attention since Stahl et al. reported the first chlorination example using LiCl as the halogen source [10]. Following this pioneering work, elegant strategies for the C5–H bromination of the quinoline ring employing simple inorganic

• chlorination and iodination reactions using ethyl chlorodifluoroacetate (6) and 1-iodobutane (8) as the respective halogenation reagents. However, these attempts ended in failure (Scheme 4, reactions 2 and 3). Furthermore, to demonstrate the synthetic usefulness of the protocol for industrial production, a

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• chlorination effects on the Qx20 series, resulting in four new NFAs, i.e., Qx22–Qx25 (Figure 4). The research revealed the strategic balance between molecular crystallinity, packing, and optical properties. Qx24 and Qx25, with lower steric hindrance in the alkyl side chains, showed slightly decreased

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• complex as a catalyst and a Brønsted base were applied in the procedure. It is interesting to note that in such a method, sulfenylation of NH-oxindoles resulted in the thiolated products with excellent enantioselectivities (up to 99% ee). In 2013, sulfenylation and chlorination of β-ketoesters 93, and 95

• . Sulfenylation and chlorination of β-ketoesters. Intramolecular sulfenoamination of olefins. Plausible mechanism for intramolecular sulfenoamination of olefins. α-Sulfenylation of 5H-oxazol-4-ones. Metal-free C–H sulfenylation of electron-rich arenes. TFA-promoted C–H sulfenylation indoles. Proposed mechanism

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• proposed to follow one of two pathways: formation of a carbocation through RPC followed by nucleophilic attack or direct RLT from a redox-active metal complex. Preliminary evidence for a radical decarboxylation/RLT cascade was reported in 1965, when Kochi demonstrated decarboxylative chlorination of

• high yields from their respective acids, a result incompatible with a carbocation RPC mechanism. This Kochi decarboxylative chlorination separated itself from other pioneering methods of decarboxylative functionalization (i.e., Barton and Hunsdiecker) because of its inclusion of RLT as a key element of

• recent work on decarboxylative functionalization involving a posited RLT pathway. I: In 1965, Kochi reported thermal and photochemical decarboxylative chlorination using stoichiometric lead(IV) acetate. LMCT on the carboxylate substrate and RLT on a Pb–Cl bond are supported by mechanistic studies. II

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• of this heterocycle is quite challenging due to the ease of the β-fragmentation pathway of lithiated derivatives (Scheme 2). Chlorination or oxygenation of the ring sulfur atom(s) in 1, followed by Pummerer-type rearrangement and elimination, affords a straightforward access to the more useful

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

• chloride and bromide where bromination occurred at higher rate, N-tosylpyridinium halide was the acylating agent in both cases. In 2017, M. Hossain and co-workers suggested a quite unique one-pot deoxygenative chlorination reaction procedure of 2-unsubstituted imidazole N-oxides using oxalyl chloride as

• tosyl halogenides. Solvent-free chlorination reaction of imidazole N-oxides. Multicomponent reaction of imidazole N-oxides 28 with Meldrum’s acid (26) and aldehydes. Multicomponent reaction of imidazole N-oxides with CH-acids and aldehydes. Reaction conditions: aThe mixture of 2-unsbstituted imidazole 1