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

Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• carbonyl groups of the urea fragment are observed (Figure 4). Values of spin–spin interaction constants 3JCH equal to 5.3–6.0 Hz indicate the cis-orientation of the vinyl proton and the carbonyl (for 4a, blue) or the carboxyl group (for 5a, red) relative to the double bond [24][25][26]. The values of spin

• –spin interaction constants of other doublets (2JCH = 1.3–1.5 Hz) indicate the position of the carboxyl (for 4a, red) or carbonyl (for 5a, blue) groups through two bonds relative to the olefinic proton. The structure of compound 5a was additionally confirmed by X-ray structural analysis data (Figure 5

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• -c]pyridines. From the analysis of the literature data [2][40][41][42][43], we suggested that the interaction of furanic amines with various aldehydes in an acidic media should be accompanied by the formation of the corresponding imine, the generation of the iminium cation, and subsequent Pictet

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

• components, asymmetric products containing a nitrogen-substituted stereocenter can be obtained. Chiral organocatalysts can easily influence asymmetric aza-Friedel–Crafts reactions. The asymmetric induction is attributed to the formation of a chiral complex through a noncovalent interaction with the imine

• . The products 16 were achieved with excellent enantioselectivites which were attributed to an attractive interaction between the indole ring and the anthracene substituent of the catalyst’s framework (Scheme 5) [29]. In 2018, Piersanti and co-workers developed a phosphoric acid-catalyzed cascade

• -unsubstituted pyrroles/indoles 4/9 and isoquinoline-1,3,4(2H)-trione-1-imines 45 installing an aza-quaternary stereocenter in isoquinoline-1,3(2H,4H)-dione frameworks 46/47. The spinol-derived catalyst P15 was applied for the asymmetric induction through H-bonding interaction with the NH group of 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

• interaction between DES and the amino group enhance the nucleophlicity of the amines. (3) Microwave-assisted reactions Microwave-assisted heating offers a number of advantages over conventional heating, such as greater precision, excellent product yields, and very rapid reaction. This section describes the

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• interaction between the drug candidate and the target protein, to further improve the efficacy of the potential drug [9]. The nitrile group can also function as a metabolic blocking site to inhibit the oxidative metabolism of molecules to improve metabolic stability in vivo [10]. Consequently, the development

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• cucurbit[6]uril (TMeQ[6]) and 1,2-bis(4-pyridyl)ethene (G) were used to construct a supramolecular fluorescent probe G@TMeQ[6]. The host–guest interaction between TMeQ[6] and G was investigated using 1H NMR spectroscopy, single-crystal X-ray diffraction and various experimental techniques. The results show

• detection of heavy metal ions. Results and Discussion The interactions of G with TMeQ[6] UV–vis spectroscopy analysis The binding interaction between G and TMeQ[6] in aqueous solution was studied using UV–vis absorption spectroscopy. Figure 2a shows that the absorbance of G decreases with the addition of

• complex with a molar ratio of 1:1. Fluorescent spectroscopic analysis The interaction between G and TMeQ[6] in aqueous solution was investigated using fluorescence titration experiments. The fluorescence titration curve (Figure 3a) shows that at the excitation wavelength of 351 nm, G has an emission peak

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

• 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

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• were not optimal and the process could be significantly improved. In order to employ the aforementioned approach for the preparation of pyrimidines containing an allomaltol moiety we initially selected the interaction of enaminone 13a with cyanamide as a model reaction. We varied time and temperature

• for the formation of pyrimidines 9 is presented in Scheme 3. At first, intermediate A is formed by Michael addition of cyanamide to enaminone 13. Further elimination of dimethylamine leads to cyanoenaminone B. Next, interaction of the cyano group with dimethylamine results in the formation of

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• plays a crucial role in activating IP towards the photoredox coupling reaction. Shifting of protons in the 1H NMR spectrum of 2-phenylimidazo[1,2-a]pyridine (1a) in the presence of Zn(OAc)2 in CDCl3 indicates a weak interaction of Zn(OAc)2 with 1a (see Supporting Information File 1 for details) [20][21

• quenching study (Scheme 3F), expressed that the photoredox reaction started with the reductive generation of a malonyl radical from bromomalonate by interaction with the photocatalyst. Analyzing all the observations from the above mechanistic studies, we propose a plausible mechanism involving sequential

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• synthesized a new chitosan bioconjugate CS-TPE with varying amounts of TPE labelling. It can self-assemble into fluorescent polymeric nanoparticles in an aqueous solution at pH 5.3, either alone or as a guest by electrostatic interaction with the TBTQ-C6 host. These nanoparticles were disassembled upon

• composed of TBTQ-C6, as illustrated in Scheme 1. Due to the electrostatic interaction between the host and guest molecules, pH is considered an influential control factor in regulating the assembly and disassembly of supramolecular nanoparticles, as changes in pH affect the protonation degree 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

• 61. On the other hand, the sterically bulky diphenylphosphorane group afforded the (R,R,R)-diastereoisomer 63 as the main product. The large protecting group likely overrides the repulsive interaction between the enolate and a phenyl group in a preferred synclinal Mg-bound arrangement of the reagents

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• deuterated acetonitrile (Figure 3). Interestingly, a change in chemical shift of the diagnostic α-protons of 2a was displayed upon addition of increasing amounts of DABCO, suggesting the presence of the halogen-bonding interaction [30]. More precisely, the 1H NMR signal of the α-hydrogens (Hα) within 2a was

• found to shift to lower ppm values because the Hα nuclei have been affected by higher electron density caused by the formation of the halogen-bonded complex between 2a and DABCO. To confirm that the shift of Hα was indeed produced by a halogen-bonding interaction, 19F NMR analysis of compound 2d, which

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• isomer (see Figure 2). The presence of the tert-butyl group induces an additional dispersion interaction between this group and the benzyl fragment in the ʟ-(AlaNi)L7 complex, bringing the benzyl group and the o-phenylene moiety even closer to each other (the distance between the C20 and C8 atoms is 3.45

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

• modelling combined with spectrophotometric experiments revealed that in neutral and acidic buffered water solutions conjugates predominantly exist in intramolecularly stacked conformations because of the π–π stacking interaction between pyrene and phenanthridine moieties. The investigated systems exhibited

• signalize complex formation (interaction with a biomolecule, cyclodextrine, metal cation, etc.) or change of receptor conformation [5][6]. Employment of pyrene as a biosensor is complicated due to its large aromatic surface's hydrophobicity and fluorescence sensitivity to oxygen. Therefore, modifications of

• solvents, including water. The exciplex was formed by the intramolecular interaction of guanine and pyrene, linked by a flexible methylene chain [10]. Our lab has conducted considerable research on phenanthridine derivatives, and earlier research has demonstrated that two phenanthridine units can also

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

• obtained value for the analysis of the full systems should be the sum of each tether calculated from the individual models plus the term representing the interaction exerted by the combination of both tethers, i.e.: ΔE≠tether = ΔE≠t1 + ΔE≠t2 + ΔE≠ti (Equation 1). In addition, and for the purpose of

• parameters for transannular cyclizations illustrated in Scheme 1.a Calculated activation parameters for transannular cyclizations illustrated in Scheme 2.a Distortion–interaction analysis for fused cyclohexanes. Distortion-interaction analysis for fused cyclopentanes and system 7-8. Comparison of relative

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• hypothesize that in this CO2 adduct, the guanidine moiety is unavailable to perform its assisting part in catalysis through hydrogen-bonding interaction [48]. As additional evidence to support the formation of the CO2 adduct of 5, we can show that bubbling of CO2 through a solution of 5 leads to catalytically

Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C

• Karolina Wątroba,
• Małgorzata Pawełczak and
• Marcin Kaźmierczak

Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33

• fluorinated aminophosphonates [23][24] with the simultaneous deprotection of the amino group. The free amines were subjected to kinetic studies to investigate their interaction with cathepsin C. The required steps should be simple and fast, and the conditions of the reactions should be as mild as possible

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• -dihydroxyphenyl- and 3-methoxy-4-hydroxyphenyl moieties in the hesperidin, naringin, and rutin aglycones or silibinin). There are many studies revealing the interaction of flavonoids, flavonoid glycosides, and flavonolignans with CDs, especially for obtaining binary complexes [42][43][44][45][46][47][48][49]. In

• a ternary complex, considering the vegetable oil as a single component, an on-site antioxidant can protect labile FA glycerides by co-nanoencapsulation into a CD cavity. However, it is very difficult to evaluate the way of interaction in such multicomponent systems. There are some studies on the CD

• FA moieties interact with the β-CD host molecules. This was the reason to use such non-equimolar ratios. If a theoretical 3:1 interaction can be considered, the formation of such β-CD/triglyceride supramolecular system in practice is limited by the steric hindrance. On the other hand, ternary

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

• a photophysical investigation, a weak interaction was observed between two subunits at ground state in porphyrin-ferrocene dyads. Also, the fluorescence of porphyrin was significantly quenched in porphyrin-ferrocene conjugates due to photoinduced electron transfer from ferrocene to porphyrin

• protocol in a 42% yield by using CuI and DIPEA in THF at room temperature (Scheme 11). Their photophysical studies revealed that the fluorescence of zinc porphyrin 58 is strongly quenched due to the copper-corrole 59 in the dyad 60. Also, an efficient excited-state interaction was found between zinc

• 45–50% yields. This click reaction was performed between 3-azido-BODIPY 77 and zinc porphyrin 35a or 21,23-dithiaporphyrin 79 in the presence of CuI/DIPEA in THF/CH3CN (Scheme 16). UV–vis absorption and electrochemical studies revealed the presence and interaction of both the moieties in the

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

• novel azoiodazinium salts (Figure 3). An N4–I1 distance of 2.540 Å with a typical T-shape structure (N4–I1–C1 angle 185.74°) implies a significant interaction between the N-heterocycle and the iodine atom for the ortho-pyrazole-substituted derivative 5bb [35]. However, the presence of an ortho-methyl

Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives

• Martin Kalník,
• Sergej Šesták,
• Juraj Kóňa,
• Maroš Bella and
• Monika Poláková

Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24

• -mannosidase II (LManII) and JBMan). Finally, structural and physicochemical properties of inhibitor:enzyme complexes were investigated at the theoretical level using molecular docking, hybrid quantum mechanics/molecular mechanics (QM/MM) calculations and fragmented molecular orbital pair interaction energy

• derivatives synthesized in this work, pair interaction energies between the bound inhibitors (29, 10, 20, 28, 30 and DIM) and amino acid residues of dGMII were calculated at the quantum mechanics level (FMO-PIEDA-MP2/6-31G*) in an active-site model of the inhibitor:enzyme complexes optimized at the hybrid QM

• /MM level (BP86/LACVP*:OPLS2005). The FMO-PIEDA results are compiled in Table 2 and visualized in Figure 3. Firstly, the results for the complex 29:dGMII were analyzed: the overall interaction energy (ΔEI-E) between 29 and the enzyme is −563.6 kcal mol−1, towards which the interaction energy between

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• against human myeloid leukemia cells, and stabilizes the 14-3-3 – TASK3 protein–protein interaction [29][30]. Sugita et al. investigated the synthesis of the core structure of cotylenol (50) first through an RCM approach on the advanced intermediate 47 (Scheme 7) [31]. Despite many attempts, the authors

• commercial cyclopentenone 69. Protection of the alcohol function was mandatory prior to the cyclization as the free alcohol substrate failed to cyclize. As proposed by the authors, interaction between the free alcohol 70 and the molybdenum metal center may explain the reaction inhibition. Thus, after

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• NMR spectra (Figure S6), indicating no interaction between the solvent and the monomer. Polymerization of 2-ethyl-2-oxazoline Six different electrophiles, acetyl chloride (AcCl), propionyl chloride (PrCl), benzyl bromide (BnBr), MeOTf, MeOTs, and EtOxMeOTf, were examined as initiators for the EtOx

• ppm attributable to the product obtained after the interaction of initiator and solvent were not observed in the resulting NMR spectra. However, lowering the polymerization temperature definitely does not lead to improvement. Finally, a temperature of 120 °C was applied to obtain the PEtOx with [M]0

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• ]. The exact nature of the interaction between the active ate-ferrous complex and the NMP-ligated magnesium cation is so far unknown. Although often neglected in the mechanistic analysis of a cross-coupling system, the importance of the coordination sphere of the main-group cation brought by the