Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• solvents screened, 1,4-dioxane was found the best solvent in terms of yield of the target product, solubility of the reagents, and ease of separation of the product. Thus, the optimal conditions found were reacting amidine 1 with azide 2 in the presence of DBU in a 1:1:1 ratio in 1,4-dioxane at room

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• °C for 2 h (Scheme 1). Figure 1 depicts the changes in the visible–near infrared (vis–NIR) absorption spectra during the reaction, showing gradual changes with isosbestic points. Since the electrolyte interferes with the high-performance liquid chromatography (HPLC) separation and anionic species may

• not be eluted under typical fullerene HPLC separation conditions, trifluoroacetic acid was added to the reaction mixture. Notably, La@C2v-C82 is produced after the addition of trifluoroacetic acid to the La@C2v-C82 anion [20]. After removing the solvent under vacuum, the electrolyte was removed by

• adding CS2 and then filtering. Subsequent HPLC separation of the reaction mixture with 1a afforded products 2a, 3a, 4a, and 5a in yields of 40, 37, 9, and 1%, respectively, based on the consumption of La@C2v-C82 (Figure 2a and Supporting Information File 1, Figure S1). The yield was estimated from the

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• long and expensive process. Therefore, for sustainable application, the cost-efficient recovery and reuse of organocatalysts are critical issues. Fortunately, a wide range of recycling options are known in the literature, often based on liquid–solid phase separation [14]. Catalyst recycling can be

• achieved, for example, by immobilizing the catalysts to a solid support [15], e.g., silica gel [16][17][18], organic polymers [19][20][21], magnetic nanoparticles [22][23], or by membrane separation, e.g., using organic solvent nanofiltration (OSN) [24][25][26], which methods can be easily implemented in

• ). After phase separation, the product was isolated from the supernatant by preparative thin-layer chromatography, while the catalyst was reused in subsequent reaction cycles. The precipitated catalyst was further washed twice with acetonitrile, and dried in vacuo. The results are collected in Table 3

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

• separation by reducing Coulomb attraction and exciton binding energy. The resulting enhancement in exciton dissociation and reduced charge recombination contribute to the improved performance of polymer acceptors, especially Qx2 which achieved PCE of 5.32% with PBDB-T donor in an all-PSC device [20]. In a

• charge separation in all-PSCs such as switching from p-type dominated behaviour of polymer Qx5 to n-type dominated behaviour of Q6, with no off state due to presence of free charge carriers in the latter case [21]. Besides optimizing polymer structures, side chain engineering, introduction of electron

• -series acceptor with the Qx moiety (Y-O6) and copolymerized it with the PBDB-T donor in two ratios to give Qx11a and Qx11b. This approach enhanced charge transport and nanophase separation, resulting in a record PCE of 13.02% in an SCOSC device made of Qx11b with diluted YO6 component [24]. Table 1

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

• luminescence efficiency, while a significant spatial separation between hole and particle wavefunctions considered for CT component promoting RISC process along high-lying excitation state for enhancing an exciton utilization efficiency (EUE). The photophysical properties of TPECNz were studied in solution

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• separation between the cation and anion. Sessler and co-workers introduced a similar ion-pair receptor, in which the calix[4]arene-strapped calix[4]pyrrole 5 demonstrated an additional binding mode of CsF (Figure 5). The binding constant Ka = 1.3·104 M−1 in CHCl3/MeOH 9:1 was reported [101][102]. This

• deviations from the N3O plane. An intriguing feature of the helicates was their short metal–metal separation (3.151 Å [Fe], 3.521 Å [Mn], and 3.104 Å [Co]) enabled by the flexibility of the ligand incorporating the sp3-hybridised meso-carbons. Crownphyrins and similar systems In 2022 our group reported on

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• filtered and analyzed by HPLC without dilution. HPLC separation was performed on a 150 × 4.6 mm i.d. CAPCELL PAK C18 UG120 column (Osaka Soda) at 35 °C with isocratic elution using 20% CH3CN in 50 mM H3PO4 for 30 min and subsequent column washing with 90% CH3CN at a flow rate 0.8 mL/min. Detection at 250

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• with CH2Cl2/MeOH 97.5:2.5 (v/v) was subjected to a flash chromatography system (PLC 2020, Gilson) equipped with a VP Nucleodur C18 HTec column (10 µm, 250 × 40 mm). The chromatographic separation was performed by using a constant flow rate of 10 mL/min with the mobile phases made with solvent A

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• synthase from Allokutzneria albata. The availability of a selective enzyme for allokutznerene is particularly interesting, because the separation of phomopsene and allokutznerene is reportedly very difficult [50]. Last but not least, a sesterterpene synthase for sesterviolene was discovered from

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

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

• -conjugation of benzoguanidine induced a larger hole–electron separation resulting in a smaller energy gap between the excited singlet and triplet states (S1 and T1) and ΔEST resulting in faster radiative rates. This study aimed to synthesize and explore the luminescent properties of the 4BGIPN material

• and E1/2 for quasi-reversible processes (*), V, vs FeCp2), onset potentials (E, V, vs FeCp2), peak-to-peak separation in parentheses for quasi-reversible processes (ΔEp in mV), EHOMO/ELUMO (eV) and band gap values (ΔE, eV) for the redox changes exhibited by 4BGIPN.a UV–vis data for compounds 4BGIPN

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• another experiment, the team chemically oxidized the sacrificial donor and regenerated it by hydrogenation. Carpenter and co-workers briefly discussed phase separation to enable sacrificial donor recycling by improving the recovery of the oxidized donor [32]. This idea was central to the works published

• facilitated the in-situ redox mediator recycling and separation. The authors actually employed this strategy using 3 different reactor configurations (Figure 2). The first and simplest ex-situ photorecycling method involved adding and extracting 2 aqueous phases containing the catalysts and reactant to

• microscopy [36][37]. In nature, chemical gradients and phase separation are maintained by compartmentalization in liposomes, micelles, and vesicles rather than at interfaces such as ITIES. Artificial photosynthesis systems are being designed to mimic this behavior and recently the field of artificial

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• , Milford, MA, USA). The solvent system was as follows; deionized H2O + 0.1% formic acid (FA, v/v) (solvent A) and acetonitrile (ACN) + 0.1% FA (v/v) (solvent B). The separation gradient was operated as follows; 5% B for 0.5 min, 5% B to 100% B for 20 min, and 100% B for 10 min. The flow rate was maintained

• Technologies, Santa Clara, CA, USA). The HPLC system’s stationary phase was composed of a C18 Acquity UPLC BEH column (Waters). The mobile phase employed was as follows; deionized H2O + 0.1% FA (v/v) (solvent A) and ACN + 0.1% FA (v/v) (solvent B). The separation gradient was operated as follows; 5% B for 0.5

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

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• transient absorption spectra showed that the charge separation takes ca. 0.6 ps, and admixtures of locally excited (3LE) state and charge separated (1CS/3CS) states formed (in n-hexane). The subsequent charge recombination from the 1CS state takes ca. 7.92 ns. Upon oxidation of the PTZ unit, the beginning

• of charge separation is at 178 fs and formation of 3LE state takes 4.53 ns. Nanosecond transient absorption (ns-TA) spectra showed that both 3CS and 3LE states were observed for the dyads showing TADF, whereas only 3LE or 3CS states were observed for the systems lacking TADF. This is a rare but

• . The Gibbs free energy changes (ΔGCS) for charge separation (CS) as well as the energy of the charge transfer states (ECS) were calculated using the Rehm–Weller equation (Equations 1–3) and the obtained values are listed in Table 4 [62][63][64]. It should be noted that the E00 values used in the

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• resin with methanol. The resulting extract was concentrated to dryness. For an initial separation of its components, the raw extract was resuspended in water and extracted three times with ethyl acetate. The organic phases were pooled. A testing in the CAS assay indicated the presence of iron-chelating

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• ), 133.8 (CH), 135.1 (C), 137.8 (C), 167.0 (C), 192.7 (C). Although the adduct was obtained as a mixture of diastereomeric isomers (54:46), these isomers were subjected to subsequent cyclization without separation. When other 1,3-dicarbonyl compounds 3 or nitrostyrene 2b were used, the reaction was

Cyclodextrins as building blocks for new materials

• Miriana Kfoury and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2023, 19, 889–891, doi:10.3762/bjoc.19.66

• solubilizers, stabilizers, permeation enhancers, cryoprotectors, sequestrants of toxic compounds, taste and odor maskers, coating materials of solid surfaces, and chiral receptors has been successfully explored in food, packaging, cosmetics, textiles, separation processes, environmental remediation, extraction

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

• including the thiolation discussed above). Insertion of the t-Bu group also makes the (GlyNi)L7 complex more soluble in diethyl ether as compared to the parent (GlyNi)L1 complex (21.3 mg/1 mL vs <1 mg/1 mL in Et2O; see Figure 3). This is beneficial for electrosynthesis, simplifying the separation of the

• the C=N bond), diffusion controlled (the slope of the ln ipc vs ln v dependence is 0.48), and reversible; the direct and reverse peak separation value was 57 mV at 100 mV/s, and Ia/Ic peak current ratio was close to unity. This means that the radical anion of (GlyNi)L7 is stable, at least in the

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

• with 300 mL of anhydrous petroleum ether (ACS reagent, 40–60 °C boiling range, Sigma-Aldrich, St. Louis, MO, USA). The extract was distilled and evaporated to dryness until no petroleum ether remained. The oil separation yield was ≈50%. The hazelnut oil was kept at −20 °C until further analyses and β

• ) of the FA glycerides to the corresponding FA methyl esters (FAMEs) [11][13]. The derivatization involved methanol–boron trifluoride (20% BF3), hexane (GC grade) and anhydrous sodium sulfate, all purchased from Merck & Co., Inc., Rahway, NJ, USA. Sodium chloride (reagent grade) used for the separation

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

• fluorescence investigation of hybrid 96 revealed that the fluorescence of zinc porphyrin was strongly quenched, and the electron-transfer quenching mechanism was validated by easy oxidation. Furthermore, femtosecond transient-absorption spectrum investigations offered proof of the charge-separation process

• . The ultrafast pump-probe technique was used to determine the photoinduced charge separation in zinc porphyrin 96 and the rate constant was found on the order of 1010 s−1, clearly showing ultrafast electron-transfer between graphene and porphyrin units. Hence, these hybrids could be useful for light

• -triazole linker significantly influences the charge separation, charge recombination, and photoinduced electron transfer processes. Since, the through-bond distance is approximately the same for all the synthesized ZnP-Tri-C60 conjugates, therefore, the variation in charge separation and charge

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• (±)-incarvilleatone (1) by utilizing an unexplored accelerated Rauhut-Currier (RC) dimerization as a key step. In addition to that HPLC separation of (±)-incarvilleatone (1) into its enantiomers (−)-incarvilleatone (−)-1 and (+)-incarvilleatone (+)-1 and their X-ray crystallographic analysis which has not yet been

• (±)-incarvilleatone (1) was confirmed by single crystal X-ray analysis [16]. We then undertook separation of both the enantiomers of (±)-incarvilleatone 1 (40 mg, Scheme 6) by HPLC using a Chiralpak IA analytical column with the mobile phase MeCN/H2O (70:30). HPLC on a chiral stationary phase resulted in the

• separation of enantiomers, (−)-incarvilleatone [(−)-1, 15 mg] and (+)-incarvilleatone [(+)-1, 14 mg]. The optical rotations of the individual enantiomers were recorded and compared with the ones of Zhang and co-workers [1] reported data and were found to be nearly the same, i.e., optical rotation of −13.0 (c

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• ) (for mass spectra see Supporting Information File 1). A minor diastereomer 14 was obtained in 9% yield after isolation by RP-HPLC using a LiChroPrep RP-18 phase because conventional column chromatography did not allow for good separation from the major products. Only one face of the carbonyl groups

• scent gland macrolides can be biosynthesized by the frogs [7], although the macrolides are produced from the fatty acid biosynthetic pathway. The gas chromatographic separation obtained with the chiral phase also allowed the determination of the identity of the minor diastereomers formed during the

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• reason for the low yield of compound 1 was eventually understood after it was determined to be a monoacylglycerol, which has a surface-active property and should have deteriorated the separation capacity of the chromatographic resins. The molecular formula of compound 1 was established to be C19H34O4

• ) to see the separation of activity at the top two and slow-eluting fractions. The top fraction was purified by repeated HPLC first on an ODS column (Cosmosil AR-II 1 × 25 cm) and second on a styrene-divinylbenzene polymer column (Hamilton PRP-1 1 × 25 cm) both eluted with MeCN/50 mM NaClO4 75:25 to

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• suitable mobile phase for the column chromatographic separation of the diastereomeric esters 16a and 16b. With the successful isolation of these esters in pure form, both were converted to the corresponding acyl chlorides 6ba and 6bb via an initial basic hydrolysis followed by treatment with oxalyl