Synthesis, characterization, and photophysical properties of novel 9‑phenyl-9-phosphafluorene oxide derivatives

• Shuxian Qiu,
• Duan Dong,
• Jiahui Li,
• Huiting Wen,
• Jinpeng Li,
• Yu Yang,
• Shengxian Zhai and
• Xingyuan Gao

Beilstein J. Org. Chem. 2024, 20, 3299–3305, doi:10.3762/bjoc.20.274

• recent years, and they are mostly based on purely organic electron donor−electron acceptor (D−A) or D−A−D systems with significant intramolecular charge transfer interactions for frontier molecular orbital separation [28][29][30]. Due to the electron-accepting properties, PhFlOP can clearly act as an

• * transitions associated with the conjugated system, while the band at around 340 nm is attributed to intramolecular charge transfer processes. The low-energy absorption bands of 7-t-Bu (λmax = 345 nm, Table 2) and 7-Cz-2 (λmax = 342 nm) are slightly redshifted compared to 7-H (λmax = 338 nm), and larger

• redshifts are observed for 7-Ph-1 (λmax = 354 nm) and 7-Ph-2 (λmax = 366 nm). In contrast to 7-H, 7-Br (λmax = 327 nm) and 7-Cz-1 (λmax = 316 nm) show a blueshift. With a stronger electron-donating ability than 7-Cz-1, 7-Cz-2 shows a lower energy level for the absorption band stemming from intramolecular

Synthesis of acenaphthylene-fused heteroarenes and polyoxygenated benzo[j]fluoranthenes via a Pd-catalyzed Suzuki–Miyaura/C–H arylation cascade

• Merve Yence,
• Dilgam Ahmadli,
• Damla Surmeli,
• Umut Mert Karacaoğlu,
• Sujit Pal and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2024, 20, 3290–3298, doi:10.3762/bjoc.20.273

• %). This cascade involves an initial Suzuki–Miyaura cross-coupling reaction between 1,8-dihalonaphthalenes and heteroarylboronic acids or esters, followed by an intramolecular C–H arylation under the same conditions to yield the final heterocyclic fluoranthene analogues. The method was further employed to

• )-catalyzed [2 + 2 + 2] cycloaddition reactions with 1,8-dialkynylnaphthalenes to access azafluoranthenes and 2-pyridone-fused naphthalenes [27]. In 2017, we reported a Pd-catalyzed cascade reaction that involves a sequential Suzuki–Miyaura cross-coupling and a subsequent intramolecular C–H arylation between

• boronic esters of 1,8-DHN have recently been investigated and reported by Krempner and co-workers [51]. To our delight, the Suzuki–Miyaura coupling/intramolecular C–H arylation sequence between 12 and boronic ester 17d proceeded smoothly affording product 15a in 84% yield. The results summarized in Table

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

• molecular density of 1.688 g cm−3. In more details, the crystal structure reveals two short intramolecular F···H hydrogen contacts in the triphenylene core part with lengths of 2.047 Å and 2.114 Å, respectively (see Figure S33 in Supporting Information File 1). The triphenylene part of the molecule is

Intramolecular C–H arylation of pyridine derivatives with a palladium catalyst for the synthesis of multiply fused heteroaromatic compounds

• Yuki Nakanishi,
• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2024, 20, 3256–3262, doi:10.3762/bjoc.20.269

• % yield, respectively. The related reaction is also carried out with amides of non-pyridine derivatives terephthal- and benzamides to afford multiply fused heterocyclic compounds in 81% and 89% yields, respectively. Keywords: intramolecular C–H arylation; multiply fused heterocycles; palladium acetate

• efficiencies in atom economy [3][4]. The extension of the reaction to an intramolecular version represents a viable approach for the construction of several fused-ring skeletons [5]. Such ring structures containing heterocyclic rings would be of crucial importance because heterocycle-fused ring structures [6

• fused structure toward a phenanthroline diamide (Phen-2,9-diamide) [23] can be achieved by employing a palladium-catalyzed intramolecular C–H arylation [24][25][26][27][28]. One of the thus obtained products exhibited a remarkable extraction performance for a lanthanide ion, in which a metal-specific

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

• hydrogen bonding with the protonated tertiary amine. Then, a Michael addition of malononitrile to the azadiene takes place to obtain exclusively the (S)-intermediate A. Subsequently an intramolecular nucleophilic addition of the nitrile leads to the intermediate B, which undergoes tautomerization to

• -derived azadiene by H-bonding. This dual activation promotes a stereoselective addition of 3-chlorooxindole to the azadiene leading to intermediate A. The latter is also activated by the chiral guanidine and undergoes an intramolecular nucleophilic substitution which delivers the product 19b with the

• the bifunctional squaramide enables a stereoselective Michael addition of the azlactone to the azadiene forming intermediate A which transforms into intermediate B, which then undergoes an intramolecular cyclization to give the desired product 20. In 2020, Ni, Song and co-workers described a

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• intramolecular Michael addition. Preliminary conformational studies on tripeptides including this scaffold in the central position show an extended conformation in solution (NMR) and in the solid state (X-ray). Keywords: fluoroalkyl groups; heterocycles; hydrazino acids; peptides; tetrahydropyridazines

• ,anti. Then, hydrazones 3 were reacted with zinc and methyl 2-(bromomethyl)acrylate (4). This aza-Barbier reaction was performed in a biphasic medium (THF/aqueous solution of saturated NH4Cl) to avoid the formation of the α-methylene-γ-lactam obtained by intramolecular cyclization of the zinc amide on

• on an intramolecular Michael addition carried out in DMF and catalyzed by 10% of potassium carbonate. As previously observed [37], under these conditions, the 5-endo-trig cyclization was selective and the lactam resulting from the 5-exo-trig cyclization was not observed. Furthermore, in the case of

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• a multicomponent reaction to obtain SIRT2 inhibitors (Scheme 12). The authors suggest a Knoevenagel condensation approach between isatin derivatives and ethyl cyanoacetate, followed by a Michael addition with C–H activated carbonyl compounds and intramolecular cyclization [50]. They synthesized 45

• intramolecular SNAr reactions. Ugi-4CR/deprotection/cyclization (UDC) strategy: In the UDC approach a protected amine and an electrophilic functional group like esters or ketones are used. Convertible isocyanides can also be employed. Once the Ugi reaction is completed, the protecting group is removed, and the

• eliminated through microwave-assisted treatment under acidic conditions, resulting in the intramolecular cyclization of the amine onto the ketone derived from glyoxaldehyde (Scheme 14). Vézina-Dawod and co-workers [60] introduced a strategy, which consists of two reactions, for synthesizing highly

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

• , the intramolecular HVI-mediated halocyclisation of alkenes using carbon, oxygen, nitrogen or sulfur nucleophiles. Herein, we describe the examples reported in the literature, which are organised by the different halogens involved and the internal nucleophiles. Keywords: cyclisation; halogenation

• ; heterocycles; hypervalent iodine; oxidation; Introduction Halogenated carbocyclic and heterocyclic compounds are present in many active pharmaceutical ingredients [1][2]. The intramolecular halocyclisation of alkenes mediated by HVI(III) reagents allow access to a range of halogenated cyclic scaffolds in a

• firstly through the coordination of an alkene by the HVI reagent, which activates it toward intramolecular attack by an internal nucleophile. Following this, substitution of the iodane(III) can occur from the nucleophilic halide in solution to reveal the halo-cyclised product (Figure 2). In this review

Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction

• Cesia M. Aguilar-Morales,
• América A. Frías-López,
• Nadia V. Emilio-Velázquez,
• Alejandro Islas-Jácome,
• Angelica Judith Granados-López,
• Jorge Gustavo Araujo-Huitrado,
• Yamilé López-Hernández,
• Hiram Hernández-López,
• Luis Chacón-García,
• Jesús Adrián López and
• Carlos J. Cortés-García

Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256

• , an intramolecular cyclization takes place, facilitated by CuI. This step involves a 5-endo-dig cyclization, where the negatively nitrogen atom of the sulfonamide 25 attacks intramolecularly to yield the intermediate 26. The final product is formed when iodide is regenerated as CuI, allowing it to re

Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond

• Thomas Ma and
• John Chu

Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253

• megaenzyme machinery. Water can act as the nucleophile during the offloading step, which amounts to hydrolysis and results in a linear peptide. On the other hand, a cyclic peptide forms when an intramolecular functional group acts as the nucleophile in this step. Regardless of the resulting topology, the NRP

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

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

• and acceptor groups arranged in a specific sequence, such as in D–π–A chromophores. This creates the conditions for efficient intramolecular charge transfer (ICT), which plays a key role in the DSE phenomenon. Also, additional substituents can affect the geometry and conformation of the molecule

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

• generate the nucleophilic carbon radical B. The intramolecular 1,5-HAT of B provided the alkyl radical C, which then cross-coupled with the in situ-generated high-valent Mnn+1OO-t-Bu species to form the 1,6-difunctionalized product 42 via peroxy-ligand transfer. The remote trifluoromethylthiolation

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• ) to iodine(I). Intermediate II then undergoes an intramolecular aryl migration, yielding the diarylated products 41, analogous to the known iodoniumphenolate reactions that produce diaryl ethers. The same research group meliorated the N-arylation of aliphatic cyclic amines with the same fluorinated

• diaryliodonium salts 40 (Scheme 18) [69], which however, does not produce the diarylated compounds. The intramolecular aryl migration from the iodine to the nitrogen leads to a quaternary ammonium ion intermediate A. Consequently, a nucleophilic ring opening of cyclic amine in 42 occurred via cleavage of the

• bond, leading to the formation of the carbanion intermediate III. Lastly, this intermediate is protonated by bicarbonate to yield the final product 74 (Scheme 30). Furthermore, Wang and his team introduced a novel method to synthesize ortho-iodo diaryl ethers 77 using intramolecular aryl migration in

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• not visible, E/Z < 2:98). The configurations were determined by comparison of chemical shifts of our products with those of non-glycosylated indirubin, by the presence of an intramolecular hydrogen bond N–H···O and by crystal structure analysis. In fact, the chemical shifts of the H-4 proton signals

• with those of non-glycosylated indirubin, by the presence of an intramolecular hydrogen bond N–H···O and by crystal structure analysis. As mentioned above for the indirubins and thioindirubins, the chemical shifts of the H-4 proton signals are strongly influenced by the anisotropic effect of the

• coumaranone carbonyl group resulting in a downfield shift in case of the Z-isomers. The different E/Z-selectivity in case of oxoindirubins as compared to other indirubin derivatives can be explained, on the one hand, by the absence of the favorable intramolecular hydrogen bond which is present in case of

Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

• Kento Iwai,
• Akari Hikasa,
• Kotaro Yoshioka,
• Shinki Tani,
• Kazuto Umezu and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238

• molecule on this cation, followed by tautomerism (path a). The intramolecular attack of an amide carbonyl on this cationic site in intermediate 10, leading to the formation of oxonium ion 11, is also possible (path b). After the addition of water, the formed hemiacetal 12 was hydrolyzed to give the

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• intramolecular cyclization were observed (Table 1, entries 3 and 4). The best results were obtained when isopropyl alcohol was used, which furnished yields of the final product 4а up to 89% within 1 h (entry 9 in Table 1). In the case of methanol and ethanol, the maximum conversion was also observed during the

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• with the generation of difluorocarbene from TMSCF2Br and KFHF. This is followed by a nucleophilic attack of the oxygen atom of ketone 1 on the difluorocarbene. Subsequently, a protonation–deprotonation sequence occurs, which can either be intermolecular, involving a molecule of HF, or intramolecular

• process. As a result, no H/D-exchange was detected. The experimental results of both experiments suggest that the reaction predominantly proceeds through an intermolecular pathway. The occurrence of the CF2D product may be attributed to a minor intramolecular reaction path or the involvement of DF formed

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• , 6a–w). Interestingly, both Cu(I) and Cu(II) can promote the reaction and the reaction is not sensitive to water (Scheme 7, 6g). The intramolecular decarboxylative yne-allylic substitution can also be achieved (Scheme 8, 6a–u). O-Nucleophiles and C-nucleophiles are all suitable reactants, yielding

• as Meldrum’s acid and 1,3-dimethylbarbituric acid were used as the nucleophiles, the yne-allylic substitution products underwent further intramolecular cyclizations to give the spiro-cyclic products in high yields (Scheme 31, 30a–f). The generation of products likely begins with an α-attack on the

• yne-allylic cation intermediate, followed by an intramolecular cyclization. The disparity in reactivity could stem from the chelation between acyclic 1,3-dicarbonyl enolates and the copper catalyst, enhancing γ-position attack in an intramolecular manner. Conversely, Meldrum's acid's rigid cyclic

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• reacts with an isocyanide and an electron-rich aniline in a three-component Ugi-type reaction to give an α-aminoamidine. This compound might undergo an additional visible light-mediated oxidation to furnish a second iminium intermediate, which acts as electrophile in an intramolecular electrophilic

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• coefficients and bathochromically shifted absorption bands which might be a result of a certain intramolecular charge transfer between the donating N,N-dimethylamino group and the electron-deficient uracil moiety. Similar effects are observed for the emission spectra. The emission maxima of N,N-dimethylamino

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• intramolecular aminocarbonylation using Mo(CO)6. Both catalytic approaches successfully produced the desired DBDAPs. As previously mentioned, organic synthesis is a crucial tool for preparing complex molecules of high value to industry. Frackenpohl et al. [13] designed and synthesized a new library of 2,3

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• as electron-donating groups was shown to promote intramolecular charge transfer (ICT) and shifted the PL wavelength to longer wavelengths, resulting in yellow or orange fluorescence in the solid state [21][22]. In addition, cross-linking between the amino group and attached benzene ring effectively

• non-radiative deactivation process. On the other hand, the other derivatives, namely 1b and 1d–f, showed increased ΦPL values in the PMMA films compared with those in the crystalline state, presumably due to a suppression of the formation of non-fluorescent twisted intramolecular charge transfer (TICT

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• results, we looked into the literature to explore examples of asymmetric FLPs. This exploration revealed three main types, namely, intramolecular chiral FLPs, intermolecular FLPs composed of a chiral acid and an achiral base, and intermolecular FLPs comprising an achiral acid and a chiral base [61][62

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• -absorbing as well as photo-antioxidant properties via an intramolecular hydrogen transfer [5]. The structure–activity relationship between the substituents of 2-hydroxybenzophenones and their UV-absorption properties has been reported previously [6]. It was concluded that the ability to absorb UV light and

• , and 4ma. Whereas compound 4ja and 4ma showed an ideal single crystal behavior, compound 4fb showed a dynamic disordered structure due to intramolecular vibrations in the unit cells, particularly because of the presence of the tert-butyl group, which can assume any rotation angle [24]. Nevertheless