A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• ]quinoline-2,4(1H,3H)-dione cyclic system. The absorption spectra of the methoxy derivatives 2f, 2j and 2n in DMF provide interesting information on the effect of the position of the methoxy group in the core of deazaalloxazine on the absorption maxima (Figure 2). The 8-methoxydeazaalloxazine 2n exhibited a

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• resulting peptides exhibit unique structural features due to thioether bridges between dehydrated serine or threonine (Dha/Dhb) and cysteine (Cys). These thioether bridges lead to cyclic peptides with the modified amino acid lanthionine (Dha-Cys) or methyllanthionine (Dhb-Cys). The strong antimicrobial

• times dehydrated was identified. Cyclization reactions introduced thioether cross-links between dehydrated Thr/Ser residues and specific cysteine thiol groups. However, due to identical masses of dehydrated linear peptides (lacking thioether rings) and cyclic forms (containing Dhb and Dha rings), a

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• cyclic imides. The solid-state structures of the N-phenyl derivatives, determined by X-ray crystallography, reveal changes in packing preference based on the number of aromatic rings in the core. The optical and electronic properties of the title compounds compare favorably with other previously

• robust polymers, supramolecular assemblies, and (opto)electronic materials. The vast majority of this research has focused on 1,2,4,5-benzene (pyromellitic), 1,4,5,8-naphthalene, and 3,4,9,10-perylene diimides. Beyond these, researchers have demonstrated that translocating the cyclic imides around the

• been achieved as well. Other efforts have demonstrated that anthracene diimides (ADIs) can be tuned to achieve decent electron mobilities in electronic settings [13][14]. Although there have been calculations conducted that suggest 6-membered cyclic imides are more compelling than 5-membered cyclic

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• . The specific quinones formed were guided by the position of an initial hydroxy group on the polycyclic aromatic hydrocarbon. An available para-position in the PAPs gave p-quinones, while hydroxy groups in the 2- or 3-position led to o-quinones. The substrates were analysed by cyclic voltammetry for

• estitmation of the HOMO/LUMO energies to shed more light on this transformation. The easy separation of the supporting electrolyte from the product will allow recycling and makes this a green transformation. Keywords: acetal formation; cyclic voltammetry; flow electrochemistry; green oxidation; polycyclic

• aromatic hydrocarbons; Introduction Quinones and their derivatives are applied in various fields such as chemical, environmental, and pharmaceutical industries [1][2][3][4]. Their cyclic diketone structures can easily transform into intramolecular unsaturated structures, and their distinct physical

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• reactions. To increase the molecular diversity at the morpholine ring, tertiary amines were formed by nucleophilic substitution. A final removal of the cyclic ketal group in aq sulfuric acid provided spiromorpholinone derivatives 134a–e, 136a–e, and 138 (Scheme 37). Spiromorpholinones were evaluated as

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• oxidation of the alcohol. Only small amounts of benzoic acid 4a’ were observed in all reactions with additional AlCl3, suggesting that the additive inhibits the previously observed overoxidation. Surprisingly AlCl3 activated the cyclic tetrazole iodane 1a but had almost no influence on the reactivity of the

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• producing divamide A. Divamide A contains a trimethylated glutamate at the N-terminus (Figure 4), which is installed by DivMT as the final step in divamide A biosynthesis. The presence of the cyclic lysinoalanine moiety is required for this post-translational modification. The addition of other N-terminal

• Epichloë. Epichloëcyclins A–E are cyclic heptameric peptides, all produced from the same precursor GigA. They carry a dimethylated lysine residue; this modification is installed as a final step in the biosynthesis by GigC. Genome mining showed that analogues of the GigA precursor are widespread in fungal

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• conformational stability of proline-rich proteins such as collagen [2]. Therefore, pyrrolidine derivatives are particularly susceptible to conformational control induced by a fluorine substituent. The 5-membered pyrrolidine ring is a cyclic alkylamine that adopts a conformation that resembles the familiar

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• semihydrogenation of alkynes to form Z-alkenes using a PEM reactor [31]. The Pd/C catalyst was essential for the reaction. They recently found that a PEM reactor with a Rh/C catalyst was effective for the stereoselective reduction of cyclic ketones [40]. Nagaki et al. reported the electrochemical deuteration of

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• ; transcriptome mining; Introduction Plants are prolific producers of cyclic peptide natural products, making 1000s of different molecules [1]. While the orbitide [2] and cyclotide [3] classes of peptides are well known, it has been recently discovered that a new class of molecules called burpitides are also

• chair) produced more than 20. Analysis of the predicted core sequence seemed to suggest moroidin-like molecules (Figure 3), but no cyclic peptides have been isolated from any member of this family. Unfortunately, sourcing members of this small family proved challenging and we were unable to evaluate

• burpitide natural products from plants. Phylogenetic visualization of the potential precursor peptides validated families known to make these cyclic peptides, but also suggested new producers. Finally, metabolomic analyses supported the predicted new sources of burpitides, aiding in our understanding of the

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

• ·2HF proved to be the best of the HF·amine reagents screened. The reaction was conducted under constant potential conditions, using cyclic voltammetry prior to electrolysis to determine the appropriate oxidation potential required for each substrate. Under these conditions, yields of up to 65% were

Tetrabutylammonium iodide-catalyzed oxidative α-azidation of β-ketocarbonyl compounds using sodium azide

• Christopher Mairhofer,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1510–1517, doi:10.3762/bjoc.20.135

• peroxide catalyzed by tetrabutylammonium iodide (TBAI). By utilizing these readily available bulk chemicals a variety of cyclic β-ketocarbonyl derivatives can be efficiently α-azidated under operationally simple conditions. Control experiments support a mechanistic scenario involving in situ formation of

• reagent/catalyst system allows indeed for high yielding direct α-azidations of different (cyclic) β-ketocarbonyl derivatives (Scheme 1C), thus resulting in an operationally simple protocol to access α-azidated carbonyl derivatives. In addition, we have also carried out some test reactions using NaNO2

• powerful approaches to access valuable organic azides. In this contribution we report the direct α-azidation of cyclic β-ketocarbonyl compounds using NaN3. This coupling of two inherently nucleophilic species is possible by carrying out the reaction under oxidative conditions using dibenzoyl peroxide in

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• using Maruoka’s spirocyclic binaphthyl-based quaternary ammonium salts B as catalysts this transformation can be achieved with enantioselectivities up to 83:17 er. Furthermore, the herein accessed cyclic products 5 could be successfully engaged in ring-opening reactions with different amines, thus

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

• Yukang Wang,
• Yan Yao and
• Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

• radicals are more challenging substrates. To our delight, both cyclic and acyclic secondary carboxylic acids performed well in our catalytic system, albeit with slightly reduced reaction efficiency (19–24). We also attempted simple primary carboxylic acids and got promising results. As outlined at the

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• reacted nicely to afford 4aq–as in 60–74% yields. This method was equally valid for β-phenylethylamine to provide 4at in 53% yield. Notably, not only linear but also cyclic primary amines were applicable for the established transformation, and targeted products 4au–ax and 4py were synthesized in 44–72

Predicting bond dissociation energies of cyclic hypervalent halogen reagents using DFT calculations and graph attention network model

• Yingbo Shao,
• Zhiyuan Ren,
• Zhihui Han,
• Li Chen,
• Yao Li and
• Xiao-Song Xue

Beilstein J. Org. Chem. 2024, 20, 1444–1452, doi:10.3762/bjoc.20.127

• both homolytic and heterolytic bond dissociation energies (BDEs) critical for assessing the chemical stability and functional group transfer capability of cyclic hypervalent halogen compounds using density functional theory (DFT) analysis. A moderate linear correlation was observed between the

• homolytic BDEs across different halogen centers, while a strong linear correlation was noted among the heterolytic BDEs across these centers. Furthermore, we developed a predictive model for both homolytic and heterolytic BDEs of cyclic hypervalent halogen compounds using machine learning algorithms. The

• results of this study could aid in estimating the chemical stability and functional group transfer capabilities of hypervalent bromine(III) and chlorine(III) reagents, thereby facilitating their development. Keywords: BDE; cyclic hypervalent halogen reagents; DFT calculation; graph attention network

Rapid construction of tricyclic tetrahydrocyclopenta[4,5]pyrrolo[2,3-b]pyridine via isocyanide-based multicomponent reaction

• Xiu-Yu Chen,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2024, 20, 1436–1443, doi:10.3762/bjoc.20.126

• -deficient alkynes [59][60][61][62][63]. The in situ generated cyclic intermediate C has a resonance hybrid C’. Then, the further nucleophilic addition of the electron-rich enamino unit to 5-(alkylimino)cyclopenta-1,3-diene intermediate C gave intermediate D. At last, the coupling of the iminium cation with

Synthesis of cyclic β-1,6-oligosaccharides from glucosamine monomers by electrochemical polyglycosylation

• Md Azadur Rahman,
• Hirofumi Endo,
• Takashi Yamamoto,
• Shoma Okushiba,
• Norihiko Sasaki and
• Toshiki Nokami

Beilstein J. Org. Chem. 2024, 20, 1421–1427, doi:10.3762/bjoc.20.124

• , Tottori University, 4-101 Koyamacho-minami, Tottori city, 680-8552 Tottori, Japan 10.3762/bjoc.20.124 Abstract The synthesis of protected precursors of cyclic β-1,6-oligoglucosamines from thioglycosides as monomers is performed by electrochemical polyglycosylation. The monomer with a 2,3-oxazolidinone

• protecting group afforded the cyclic disaccharide exclusively. Cyclic oligosaccharides up to the trisaccharide were obtained using the monomer with a 2-azido-2-deoxy group. Keywords: cyclic oligosaccharide; electrochemical glycosylation; glucosamine; polyglycosylation; Introduction Electrochemical

• reactions. Therefore, electrochemical polymerizations can be utilized for selective synthesis. Cyclic oligosaccharides are an important class of host molecules, and some natural cyclic oligosaccharides are produced by enzymatic processes. However, the corresponding chemical syntheses are still primitive [6

Challenge N- versus O-six-membered annulation: FeCl₃-catalyzed synthesis of heterocyclic N,O-aminals

• Giacomo Mari,
• Lucia De Crescentini,
• Gianfranco Favi,
• Fabio Mantellini,
• Diego Olivieri and
• Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

• a new example of cyclic N,O-aminals and carbinolamine derivatives, an interesting class of organic compounds that are common structural motifs embedded within diverse biologically important natural products and pharmaceuticals [32][33][34][35][36][37]. On the other hand, the N,O-aminals are stable

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• optimized or slightly modified conditions, cyclic secondary, and tertiary alkyl carboxylic acids were smoothly coupled with 1,1-diphenylethylene to give 3i–m. α,α′-Diarylated ketones serve as crucial building blocks in the construction of both natural and synthetic compounds with significant biological

• iodide leads to the formation of 23, which further undergoes 5-endo-trig cyclization, followed by fragmentation to produce an alkyl radical and a cyclic thiocarbonate 25. These alkyl radicals then interact with B2cat2 (19) to produce a variety of structurally intricate boronic esters. The reaction occurs

• final reductive elimination gives the desired alkene and Ni(I). The two catalytic cycles are finally completed by single-electron reduction of [Ni(I)] by [Ir(II)], which regenerates [Ni(0)] and ground-state [Ir(III)]. Cyclic oxalates readily form the corresponding alkyl radicals under iridium

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• ) acetylacetonate, the nanobracket 4b and HiPco SWNTs were bath-sonicated for 9 h in 2-propanol. Meanwhile, 4b is assumed to form complexes with SWNTs. After copper(II) acetylacetonate was added to the mixture, the cyclic Cu-nanobrackets 1b would be formed to interlock SWNTs with appropriate diameters during

• mechanically interlocking cyclic molecules are reported not to be removed with washing [11][22][23][24]. In addition, these Raman signals of 1b shift to higher frequencies at e- and i-SWNTs, similarly to our previous report [11], probably due to the structural change of Cu-nanobrackets 1b, or the energy

• transfer between the interlocked SWNTs and the cyclic Cu-nanobrackets. After thorough removal of the host molecules with DTT, weak signals are remained at p-SWNTs, known as intermediate frequency modes (IFM) of SWNTs [25]. The IFM signals are also observed in e- and i-SWNTs, showing the coexistence of both

Phenotellurazine redox catalysts: elements of design for radical cross-dehydrogenative coupling reactions

• Alina Paffen,
• Christopher Cremer and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2024, 20, 1292–1297, doi:10.3762/bjoc.20.112

• this reaction: PTeZ1 (3aa, 73% after 3 h). In other words, the cyclic phenotellurazine character of the catalyst does not seem to be essential in the context of this particular reaction, as opposed to the ortho/para substitution pattern of Te- and N-atoms. Nevertheless, all results considered, we

• elected at this point to keep the cyclic phenotellurazine structure of the catalyst in the hope of increased catalytic robustness, especially in view of further increasing substitution. Next, we therefore tested methoxy-substituted PTeZ2, a successful catalyst structure which we recently developed for the

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• molecular orbital (LUMO). To understand the electron affinity of t-Bu-FIDS, cyclic voltammetry was conducted. The cyclic voltammogram of t-Bu-FIDS in o-DCB showed reversible reduction waves at E1/2 = −1.14 V and −1.51 V (vs Fc/Fc+), as shown in Figure 3. Both the first and second reduction potentials of t

• -Bu-FIDS (black) and of toluene used to rinse the evaporated film of t-Bu-FIDS (red). Single-crystal structure of t-Bu-FIDS. (a) The π–π distance between two molecules. (b) Crystal packing. Cyclic voltammograms of fullerene derivatives in o-DCB solution containing Bu4N+(CF3SO2)2N− (0.1 M) as

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• , Supporting Information File 1). It allowed the molecule to self-align in a repeating cyclic ring pattern in one dimension. The molecular structure of the diorganyl monoselenide 12 is shown in Figure 6. It crystallized in an orthorhombic crystal system in the space group P21212. The C–Se–C bond angle was

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• best and afforded cyclic congeners from N3-[6]CMP to N6-[12]CMP (Figure S1, Supporting Information File 1) and isolated N3-[6]CMP (3a) and N4-[8]CMP (3b) in 7% and 3% yields, respectively [14]. Comparisons of the UV–vis spectra of the doped and undoped congeners revealed dopant-induced changes in the