Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• to be able to produce meaningful changes in the reactivity of the cage [28][29][30][31][32]. In 2018, our group reported a catalytic process to transform C60 in bis(fulleroid) derivatives [33][34][35]. This transformation encompassed a partially intermolecular Rh-catalyzed [2 + 2 + 2] cycloaddition

• explore, both experimentally and computationally, the Rh-catalyzed intermolecular [2 + 2 + 2] cycloaddition reaction between diynes and C70 as a new procedure to generate C70 bis(fulleroids). We are particularly interested in the analysis of the regioselectivity of this [2 + 2 + 2] cycloaddition. Results

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• 5. As the XRD study of the crystals showed (Figure 3), the molecular and crystal structure of the isolated compound is strongly dominated, on the one hand, by intra- and intermolecular hydrogen bonds with the participation of N, Cl, and O heteroatoms (forming an endless slightly corrugated ribbon

• the present work, we succeeded in filling this gap by growing crystals of base 5 from pure acetonitrile. It turned out that molecule 5 is capable of self-association through multiple C–H…N–H-bond-like contacts involving pyridyl C(3)H and C(4)H protons (Figure 5). These intermolecular contacts, whose

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• melting point of indigo is bifurcated intra- and intermolecular hydrogen bonding [11], and face-to-face π–π stacking of parallel aromatic rings (Figure 2) [12]. Single crystal X-ray diffraction analysis showed that the indigo molecule is almost planar and exists in the E-conformation. The central C=C bond

• the Z-isomers in comparison with the E-forms [62]. In 2018, Nagasawa and co-workers provided a detailed investigation of the influence of solvent polarity and intermolecular hydrogen bonding on the photoisomerization of N,N'-diacetylindigo (9a) by transient absorption spectroscopy [63]. In principle

• , it was already known that the intermolecular hydrogen bonding with solvent molecules may hinder the photoisomerization of indigo derivatives [46]. Nagasawa and co-workers found that the photoisomerization of 9a was inhibited by polar DMF due to formation of weak hydrogen bonds with formyl groups

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• substrates to be submitted to the one-pot tandem transformation (Scheme 5). With only a few exceptions, the presence of ortho (R1), meta (R2), or para (R3) substituents on the benzyl moiety generally allowed the intramolecular Friedel–Crafts reaction, after the first intermolecular one in the presence of

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• intramolecular proton transfer and the methanol-mediated proton transfer, can occur. It has been described that intermediate B is more stable with enolizable electron-withdrawing groups such as esters [50] when compared to, e.g., a nitrile [49]. Accordingly, the intermolecular proton transfer pathway should be

• carbonyl moiety and for the intermolecular proton transfer in the presence of the hydrogen-donor solvent methanol. Yields and characteristic 1H, 13C, and 31P NMR shifts of compounds 2a–i. Supporting Information Accession codes CCDC 2287962 and 2287963 contain the supplementary crystallographic data for 2a

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• the following section. Small differences between the results obtained for the solutions and films appear to be due to different intermolecular interactions, which differ in solid films (between target molecules only) and solutions (between target molecules and molecules of the solvent) of the

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• transformations, as depicted in Scheme 14. The dual-catalytic cycle comprised a photocatalytic cycle and a copper catalytic cycle, interconnected through an intermolecular single-electron transfer. Within the context of the photocatalytic cycle, the generation of the C(sp3)-centered alkyl radical A was

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• excellent photoelectric properties such as strong emission, efficient excimer formation, and suitable intermolecular stacking for good charge carrier transport. They have been applied as active layer in OFETs with high ambipolar mobility due to their well-defined monocrystalline microstructures resulting

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• antiparallel dimers (marked as *) sandwiched between two non-parallel molecules. The planes in hdz-NO2 present similar intermolecular interactions, but they grow as (101) planes. The columns also present the antiparallel dimers, but they are intercalated by antiparallel slipped molecules (Figure 2C). The

• ), it becomes possible to calculate the contribution of each type of intermolecular interaction to the whole profile [44]. In our case, results show that the sum of π···π and C–H···π contacts comprises almost 20% of the Hirshfeld surface for both compounds. The curvedness maps were also plotted over the

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

• their optoelectronic properties to highlight the potential of their experimental exploration [33]. The introduction of an electron-withdrawing group has been shown to be a key strategy for enhancing intermolecular interactions and improving the optical absorption, molecular packing, and charge transport

• collection, while their extended conjugation enhances light absorption across a broad spectrum. Qx’s unique structure promotes effective incorporation into the dye-sensitized layer, ensuring good intermolecular connectivity and facilitating electron transport. In addition, they enable efficient electron

• of structural modification, the introduction of various functional groups into Qx derivatives has allowed for the precise control of energy levels, bandgaps, and carrier transport properties. For instance, Sharma et al. fine-tuned the intermolecular charge transfer (ICT) transitions and emission

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• with the PLQY dropped to 35% due to intermolecular interactions. However, the emission efficiency of the molecule is enhanced in the solid powder form with a PLQY of 64% owing to its AIE nature. To gain more information about the effect of the solvent on the optical properties of TPECNz, the absorption

• intermolecular steric interaction [53]. The weak AIE characteristic of TPECNz in the aggregate state could be attributed to the competition between the twisted ICT and AIE properties in the molecule [57][58]. The thermal properties of TPECNz were studied by thermogravimetric analysis (TGA) and differential

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• ]. Therefore, it is important to design CIL materials to have polar groups, appropriate FMO energetic levels, and functional groups known to promote ideal packing and intermolecular interactions with neighboring compounds. Several CIL compounds stand out as top-performing materials, such as PFN-Br [13], PDIN

• physical properties, the addition of benzyl and pentafluorobenzyl groups serve to break up NH···OH intermolecular bonding, which renders the materials soluble in a range of solvents suitable for solution processing [24]. Target organic solvents to use for the production of OPVs are those that are

• nitrile functional group would stabilize both the HOMO and LUMO, where a deep-lying LUMO energy level is sought after for increased stability of electron-transporting materials [25]. Additionally, the presence of a nitrile group introduces an additional means for intermolecular bonding between the CILs

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• (PBE0-D4/def2-mTZVPP/CPCM(DMSO) structures of these complexes. The lengths of intermolecular hydrogen bonds between R[4]A and amines are marked in green, while the intramolecular hydrogen bonds between the oxygen anion and the hydrogen atom of the adjacent hydroxy group in R[4]A are marked in violet

• fact may justify the absence of the formation of complexes with 1:3 and 1:4 stoichiometry. To evaluate the contribution of various types of intermolecular interactions in stabilizing the formation of R[4]A complexes with amines, calculations were performed using the HFLD method with the def2-TZVP(-f

• stoichiometry between R[4]A and dipropylamine and diisopropylamine. The intermolecular hydrogen bonds between the amines and R[4]A molecules are marked in blue, while the intramolecular hydrogen bonds between the oxygen anion and the hydroxy group in R[4]A are shown in violet. pKa values of protons of hydroxy

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

• chlorinated product 21 was detected, which with POCl3 gave the cyclized product 22. Also, the synthesis of benzo[b]thieno[2,3-c]quinolone 24 as an anticancer molecule was demonstrated in this approach (Scheme 13). An intermolecular sulfenoamination of alkenes 9 with sulfonamides 25 as the nitrogen source and

• the presence of N-(2-bromophenylthio)succinimide 1’ and copper catalyst led to intermolecular sulfenoamination of alkenes and subsequent C–N coupling to produce dihydrobenzothiazine structures 27 in a one-pot manner. Furthermore, deprotection of the amine unit by K2CO3 and Na metal was performed in

• alcohols. Arylthiolation of arylamines with (arylthio)-pyrrolidine-2,5-diones. Catalyst-free isothiocyanatoalkylthiation of styrenes. Sulfenylation of (E)-β-chlorovinyl ketones toward 3,4-dimercaptofurans. HCl-promoted intermolecular 1, 2-thiofunctionalization of aromatic alkenes. Possible mechanism for

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• interesting rearrangement with the intermolecular transfer of a phenyl group in the starting methoxy-substituted enone 2j under the rather harsh reaction conditions (TfOH at 80 °C). To study the cyclization further, reactions of some hydroxy ketones 1 were run for shorter time (1–4.5 h) in TfOH at 80 °C, i.e

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• directly related with the overlap integral between HOMO and LUMO orbitals and influences the energy differences between first singlet and triplet excited states [14]. Therefore, we expect a marked difference in the photophysical properties for 4BGIPN, vide infra. Analysis of the intermolecular interactions

• revealed that 4BGIPN molecules experience face to face intermolecular π–π stacking interactions between the benzoguanidine moieties similar to 4CzIPN (reported by Etherington et al., [12]). The average interplanar distance for close neighbor benzoguanidine moieties in 4BGIPN is 3.322(3) Å, which is

• significantly shorter (0.4 Å) than the 3.74(3) Å average distance between nearest neighbor carbazole ligands in 4CzIPN, indicative for much stronger intermolecular interactions. Cyclic voltammetry was used to analyze the redox behavior of 4BGIPN in THF solution containing [n-Bu4N]PF6 as supporting electrolyte

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• , where the byproducts typically associated with free carbene formation (e.g., dimerization or rearrangement) were not observed (Scheme 2). In 1988, Hadjiarapoglou was investigating transition metal- and photocatalyzed intermolecular cyclopropanations between ylide 8 and norbornene, and found indane 9 was

• reductive elimination of iodobenzene to give 11 (Figure 5, left). This was also the pathway subsequently suggested by Gallos et al. [116] for the synthesis of 13/14 from 12. In 2003, Hadjiarapoglou further investigated the intermolecular reaction between 8 and cyclopentene under thermal, metal-free

• acceptor [61]. Beyond simply considering the strength of these bonds, other characteristics of this interaction should directly impact the outcomes of the reactions that they undergo. For instance, Mulliken’s initial description of an intermolecular halogen bond was of a charge transfer complex (also known

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• ). Nucleophilic addition of the amine to the acyl radical and amine-assisted intermolecular proton transfer [84] generates the α-hydroxy radical 24 from which formation of the amide 25 proceeds either via i) oxidation by [Ir2]+ and deprotonation or ii) radical chain propagation [85]. Electron-deficient, electron

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• expansion of the substrate scope was demonstrated by incorporating a β-naphthol ring as the C3 substituent of the indole moiety (substrate 73). In all classes of bi(heteroaryl) substrates, a phenolic OH group at the ortho-position was crucial as it was involved in an intermolecular hydrogen bonding with the

• potential electrophiles, N-methoxycarbonyl-substituted aldimines 105 were explored to activate the para-carbon of the phenol derivatives catalyzed by the chiral pyrophosphoric acid Py1. The high regioselectivity was mainly caused by catalyst–substrate interactions via intermolecular H-bonding which could

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

• proximal C–H functionalizations in pyridine substrates under different catalytic systems. However, the intermolecular undirected distal C–H functionalization in pyridine remained unstudied. In these circumstances, the distal C–H alkylation by addition of the pyridine C–H bond to an aldehyde 50 under

• reactions are very scarcely reported which specifically include the intramolecular C–H alkylation of pyridine with alkenes at the C3 or C4 positions. Hence, very recently in 2022, Shi and co-workers [64] adopted an intermolecular process and reported the enantioselective para-alkylation of pyridines with

• styrenes 64 using a Ni–Al bimetallic system and NHC ligand 65 through intermolecular hydroarylation with high levels of enantio- and regioselectivity in the alkylated products 66 (Scheme 13). Also, the authors performed DFT studies revealing the reaction mechanism and supported that the interaction of the

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• aldol addition step was performed either in a two-component (intramolecular aldol) or a three-component (intermolecular aldol) arrangement. The enantioselective implementation of this methodology was realized by Herraiz and Cramer in 2021 (Scheme 53) [98]. The reaction sequence is initiated by the C–H

• activation of aryl pyrazoles, followed by the asymmetric conjugate addition to the Michael acceptor. Then, the formed cobalt enolate participates in the intermolecular aldol reaction with an aldehyde 207. The stereochemistry of this tandem procedure is controlled by the chiral Co(III) complex C4 bearing

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• ]. Excimers are formed when pyrene moieties form supramolecular complexes by intermolecular or intramolecular π–π interactions, causing a significant shift of single pyrene bands to longer wavelengths. Pyrenes are often used as a sensor part of receptor molecules, so their excimer bands switch on/off to

• applications [9]. These compounds have a very large aromatic surface suitable to form self-assembled supramolecular structures by intermolecular π–π interactions and showed excimer fluorescence in thin film and in the solid state. Kawai et al. reported exciplex formation between pyrene and guanine in polar

• decrease of UV–vis spectra upon heating up to 90 °C and a baseline increase indicated intermolecular stacking and aggregation of compounds, which was more pronounced for Phen-Py-2. Spectroscopic characterization data are given in the Table 1 and Supporting Information File 1, Figure S1. A linker between

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• product 19c, the latter was obtained in a greatly reduced yield, perhaps due to less ring strain providing a thermodynamic driving force. In 2013, Mannathan et al. discussed a Ni-catalyzed intermolecular three-component difunctionalization of oxabicyclic alkenes 1 with organoboronic acids 20 and alkynes

• 25. Transmetalation of 25 with the organoboronic acid gives intermediate 26, which upon reductive elimination affords the difunctionalized product 21 and regenerates the Ni(0) catalyst. In 2019, the Stanley laboratory explored the Ni-catalyzed intermolecular three-component carboacylation of

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• also carried out an analysis of the electron localization function (ELF) [31][32] and the charge transfer along the reaction coordinate to determine the different stages and the polarity of the reaction. Results and Discussion The enantioselective intermolecular cycloaddition between hydrazones and

• groups the global charge transfer is not so high to be considered a polar process. The reaction, as previously reported by the classical intermolecular reaction takes place smoothly by the action of the organocatalyst that renders a protonated hydrazone as the reacting functional group. However, in

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• porphyrin groups were observed in nonpolar solvents. In addition, UV–vis and fluorescence spectra also showed that the 1,2,3-triazole moiety can stabilize zinc porphyrin by forming an intermolecular coordination complex. Also, it was found that porphyrin complex 160 is easy to synthesize, is fat soluble and

• . Furthermore, these two structurally similar porphyrins 166a,b were used as hosts for the intermolecular formation of inclusion complexes with tetrasodium tetraphenylporphyrintetrasulfonate 132 in aqueous solution, leading to the constructions of two different nanoarchitectures with alternating porphyrin and