Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• -mediated domino reaction of chromone-3-carboxaldehydes and amines [41], Pd-catalyzed redox-neutral C–N coupling reaction of iminoquinones with electron-deficient alkenes [42], NH3 insertion into o‑haloarylynones [43], gold(III)-catalyzed azide-yne cyclization [44], Michael/Truce-Smiles rearrangement

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

• colleagues reported on the photocatalytic decarboxylative alkenylation reactions facilitated by cooperative NaI/PPh3 catalysis [9]. These conversions involved the coupling of 1,1-diarylethene/cinnamic acid derivatives (1, 2) with redox-active esters 3 (Scheme 3). Notably, the reactions were driven by blue

• the photoredox cross-coupling reactions discussed above. A recent elegant study conducted by Chen and colleagues introduced a straightforward method that directly employed sodium iodide for photoinduced deaminative alkenylation processes [11]. This method enabled the synthesis of β,γ-unsaturated

• radicals for alkenylation, was primarily facilitated by the electrostatic interaction between NaI and Katritzky salts 7. This innovative approach not only expanded the scope of photoredox cross-coupling reactions but also offered valuable insights into the role of NaI in facilitating these transformations

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• the reaction used to complete rotaxane synthesis, hence the name “active template”. This strategy was first applied by Saito and co-workers [35], using a Cu(I) template to catalyze a Glaser coupling reaction. The method has been extended for other reactions, for example Ni-catalyzed homocoupling of

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• -withdrawing property of the trifluoromethyl group is key to this coupling reaction [45] (Scheme 7). Trifluoromethylated hydrazonoyl halides Hydrazonoyl halides, which offer a reactive 1,3-dipole, can easily be transformed to nitrile imines in the presence of a base, and they have shown to be useful building

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

• coupling constants, can be found in Table S5 of Supporting Information File 1. The azomethine hydrogen H7 appears as a singlet at 8.58 ppm for hdz-CH3 and is slightly deshielded in the nitro-derivative, resonating at 8.74 ppm, since the electron density-withdrawing substituent in hdz-NO2 increases the

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

• [11], laser dyes [12], and DR/NIR electroluminescent devices [13][14][15][16][17][18]. However, DR/NIR chromophores typically suffer from low photoluminescent quantum yields (PLQY) because of their intrinsic small band-gap energy causing larger vibronic coupling between the ground and excited states

• loss through the vibronic coupling natures of the DR/NIR fluorophores [53]. As a result, TPECNz effectively possesses a strong deep-red emission with combined HLCT, weak AIE, and ambipolar transporting properties, which enabled its application as non-doped emitter. The TPECNz-based non-doped deep-red

• OLED realized a maximum external quantum efficiency (EQEmax) of 3.32% with an emission peak at 659 nm. Results and Discussion The designed TPECNz molecule was synthesized by a multistep reaction as described in Scheme 1. Initially, an Ullmann coupling reaction of bromo-TPE 1 and carbazole provided TPE

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

• quantum filtered (DQF)-COSY correlations (Figure 2). The spin–spin coupling constants (SSCCs) in the 1H NMR spectrum and the rotating-frame Overhauser effects (ROEs) between H-2β/H-3, H-2β/H-5β, H-3/H-4, H-3/5β, H-4/H-5α, H-4/H-17, H-5α/H-6, H-5β/H-6, H-11/H-12, H-12/H-13β, H-16/H-22(24), and H-17/H-21(25

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• ]. The semiquinone radicals formed during the oxidation of catechol can undergo a cross-coupling reaction to form polymers (Scheme 1). One example is the radical polymerization of urushiol. The earliest recorded application of natural radical polymerization can be traced back to the manufacture of

• addition. The termination step occurs by either disproportionation (radical β-elimination, Equation 4) or biradical coupling (Equation 5). Chain transfer (Equations 6–8) is usually considered as a type of side effect in radical polymerization [18]. It occurs between the growing chain and a transfer agent

• decades [28]. 1.3.1 Deactivation by reversible coupling: In 1982, Otsu and Yoshida [29] successfully polymerized styrene and MMA using dithiocarbamate compounds, and in 1986, Solomon et al. [30] published a patent entitled "Polymerization Processes and Polymers Produced Thereby", which led to the

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

• /USA) 500 MHz Avance III spectrometer with a BBFO (plus) Smart Probe (1H NMR: 500 MHz and 13C NMR: 125 MHz). Chemical shifts (δ) were reported in ppm using tetramethylsilane (TMS) (Sigma-Aldrich) as an internal standard, while coupling constants (J) were measured in hertz (Hz). Optical rotations were

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• and beyond. The Z-geometry of INT-1 was determined from its 3JH−F coupling constant of 35.7 Hz in the 1H NMR with a matching J value in the 19F NMR. This is in agreement with Cao’s report on the geometry of N-(α-fluorovinyl)azoles [33]. The configurations of the E- and Z-isomers were determined by

• their 3JH−F coupling constants in the 1H NMR spectra, circa 32.0 Hz for Z-isomers and 8.0 Hz for E-isomers [33]. A peak was observed at −158.2 ppm in the 19F NMR spectrum after 2 h of the reaction, which could be the fluoride salt of the dimorpholine adduct. This peak was also found when the reaction

Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• berberine variants none are as easily modulated to rapidly install substituent diversity [31][43][44][45][46][47][48]. The method deemed most amenable to varying substituents involves substituted 2-bromo-1-aminonaphthalenes which are used in subsequent palladium cross-coupling reactions [45]. As such, our

• complete decomposition. With the desired naphthylamines in hand, we were able to complete our synthesis of four chelerythrine variants as shown in Scheme 7. After N-formylation providing intermediates 11 and 12 in good yield, a three-step sequence was performed: Suzuki coupling of the aryl bromide with one

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

• functional materials and indispensable synthetic intermediates in drug discovery [31][32][33]. Because of their value, constructing C–S bonds has attracted significant attention via metal-catalyzed cross-coupling reactions and metal-free C–S bond formation [34][35][36][37]. Direct sulfenylation of the C–H

• science and the pharmaceutical area, there is a force for researchers to identify sustainable methodologies for efficient C–S bond coupling under mild reaction conditions for achieving these distinguished compounds. Recently, several reviews about sulfenylating reagents have been reported [41][42][43]. To

• -coupling, and direct sulfenylation reactions, which are classified into three categories: sulfenylation catalyzed by i) transition metal catalysts, ii) organocompound catalysts, and iii) catalyst-free sulfenylation. Review Sulfenylation of organic compounds by N-(sulfenyl)succinimides/phthalimides Metal

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• , the pathway to 1 can be reconstituted in vitro using the methyltransferase humMT from Micromonospora humi for the methylation of dimethylallyl diphosphate (DMAPP) to 2-methylisopentenyl diphosphate (2-Me-IPP) [25], followed by coupling with DMAPP to 2-Me-GPP and terpene cyclisation using farnesyl

• ppm) for 1H NMR and the 13C signal of C6D6 (δ = 128.06 ppm) for 13C NMR [39]. Coupling constants are given in Hz. IR spectra were recorded on a Bruker α infrared spectrometer with a diamond ATR probehead. Peak intensities are given as s (strong), m (medium), w (weak) and br (broad). Optical rotations

• coupling of DMAPP and 2-Me-IPP to 2-Me-GPP, and 2MIBS for the conversion into 1. Enzymatic synthesis of analogs of 1. A) Preparation of 2 from DA-4 and IA-1, B) preparation of 3 and the inseparable mixture of 4 and 5 from DA-5 and IA-1, C) structures of 2MIBS side products 6 and 7, and D) the

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• 1,4-silylation of hex-3-ene-4-one. An efficient conversion was observed in both cases and the silylated products were isolated in good yields (Scheme 37) [42]. Recently, in 2021, Cheng and Mankad reviewed NHC–Cu(I)-catalyzed carbonylative coupling reactions including the carbonylative silylation of

• [75]. However, the major drawback with using these catalysts in A3 reactions was the loss of the catalyst at the end of the reaction. Furthermore, on using Au(I), Ag(I), and Cu(I) in ionic liquids, as well as supported Au(III), Ag(I), CuI, and CuCl to catalyze A3 coupling reactions under heterogeneous

• conditions, although the transition-metal catalysts were preserved, the reactions require high temperature conditions [76]. In 2008, Wang and co-workers [77] for the first time employed an NHC–Cu(I) complex (2 mol %) and its silica-immobilized version 141 (2 mol %) as catalyst for an A3 coupling reaction

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• these results [37][38]. For several years, our group was interested in preparing multivalent carbohydrate mimetics [39][40][41][42][43] on the basis of efficient coupling reactions of aminopyran and aminooxepane derivatives with suitable linker elements. Hence, the aminopyran derivatives A could be

• aminopyrans [54], should be converted into divalent compounds via coupling of the terminal propynyl group with benzylic biazides. Since biazides are potentially explosive [22] it was very desirable to avoid their isolation and to generate these reactive species in situ from the corresponding benzylic halides

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• transition-metal catalysis [31], we disclosed an activating group-free alkynylation–cyclization sequence to (aza)indoles [32][33] that could be readily concatenated with a concluding N-alkylation of the 7-azaindole intermediate in the sense of consecutive three-component coupling–cyclization–alkylation

• synthesis of 1,2,5-trisubstituted 7-azaindoles [34]. Inspired by the coupling–cyclization–alkylation sequence and the stepwise Sonogashira coupling–cyclization–iodination protocol to give valuable 3-iodoindoles by Amjad and Knight [35], we reasoned that the interception by an electrophilic iodination step

• N-iodosuccinimide prior to N-alkylation to give substituted 3-iodoindoles in a concise consecutive four-component fashion in modest to good yields. These target compounds are versatile building blocks for instance for a Suzuki coupling to give 1-alkyl-2,3-diarylindoles that can be of particular

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• ., Zibo 256401, China 10.3762/bjoc.19.98 Abstract A visible-light-induced nickel-catalyzed cross coupling of alkyl carboxylic acids with N-trifluoroethoxyphthalimide is described. Under purple light irradiation, an α-hydroxytrifluoroethyl radical generated from a photoactive electron donor–acceptor

• complex between Hantzsch ester and N-trifluoroethoxyphthalimide was subsequently engaged in a nickel-catalyzed coupling reaction with in situ-activated alkyl carboxylic acids. This convenient protocol does not require photocatalysts and metal reductants, providing a straightforward and efficient access to

• trifluoromethyl alkyl acyloins in good yields with broad substrate compatibility. The complex bioactive molecules were also compatible with this catalytic system to afford the corresponding products. Keywords: alkyl carboxylic acids; cross coupling; EDA complex; nickel catalysis; trifluoromethyl acyloins

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

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• are widespread as essential building blocks in various drugs, natural products, agrochemicals, and materials. Modern economy requires developing green strategies with improved efficiency and reduction of waste. Due to its atom and step-economy, the cross-dehydrogenative coupling (CDC) reaction has

• become a major strategy for ether functionalization. This review covers C–H/C–H cross-coupling reactions of ether derivatives with various C–H bond substrates via non-noble metal catalysts (Fe, Cu, Co, Mn, Ni, Zn, Y, Sc, In, Ag). We discuss advances achieved in these CDC reactions and hope to attract

• interest in developing novel methodologies in this field of organic chemistry. Keywords: alkylation; cross-dehydrogenation coupling; ether; non-noble metals; Introduction Since the 1970s, organic chemists have developed many selective cross-coupling methods for the construction of C–C bonds, such as the

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• MHz) and 13C NMR (100 MHz) spectra were recorded in CDCl3 on a Jeol ECX-400P (400 MHz) NMR spectrometer. Chemical shifts are reported in δ scale in parts per million (ppm) relative to CDCl3 (δ = 7.26 ppm for 1H NMR and δ = 77.00 ppm for 13C NMR). The coupling constants are expressed as (J) and are

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

• artificial photosynthesis. Systems for photocatalytic carbon dioxide reduction are optimized using sacrificial electron donors. One strategy for coupling carbon dioxide reduction and water oxidation to achieve artificial photosynthesis is to use a redox mediator, or recyclable electron donor. This review

• because it can allow coupling of different reaction systems [2][8]. This strategy also works well for developing photoelectrochemical systems where the oxidation and reduction can be confined at separate electrodes. When developing reactions for carbon dioxide reduction in a modular fashion isolated from

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

• employed in numerous reactions such as metallocarbene chemistry [3][4][5][6][7][8], cycloadditions [9][10][11][12][13][14], and radiofluorinations [15][16][17][18]. As with most HVI reagents, reactions of iodonium ylides are often described using terminologies (e.g., ylide transfer, coupling or reductive

• resulting in two different ligand coupling outcomes. While most of their reactions expel an iodoarene to produce functionalized β-dicarbonyl motifs, ligand coupling with the arene motif is also possible, such as in the (radio)fluorination of iodonium ylides. Finally, intramolecular σ-hole bonding offers the

• analogous free-carbene mediated reactions, and they instead proposed iodine to have engaged with Lewis basic ligands and coordinated their coupling within its ligand sphere. An ylide’s positively charged iodine was consistently proposed to accept ligands, via either concerted or ionic steps, ultimately

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

• careful comparison of the 1H and 13C NMR data with those of related compounds and ROESY correlations. The orientation of H-3 (δH 4.68, t, J = 2.8 Hz) was determined to be β based on comparing the measured and the reported coupling constants and chemical shifts for related lanostanoid derivatives [13][23

• ][29][30]. Indeed, when the proton H-3 has a β-orientation as in compound 1, it resonates in the form of a broad singlet or else in the form of a triplet with a small coupling constant indicating its equatorial disposition [31][32]. When this proton has an α-orientation, it resonates as a doublet of

• doublet with coupling constants around 4.5 and 11 Hz [28][33]. The β-orientation of H-3 in compound 1 was further supported not only by the ROESY correlation observed between H-3 (δH 4.68, t, J = 2.8 Hz) and Me-29 (δH 0.95, s), but also by the fact that 3-epipachymic acid (3) and 3α,25S-3-O-malonyl-23

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

• halides and the coupling products were obtained in good yields (52–74%) (Figure 4B). To suppress the rapid HAT with solvent DMF that yields the dehalogenated product, DMSO was chosen as solvent for the C–H arylation. When applying the catalytic protocol to 2-allyloxy-1,3,5-tribromobenzene, the 5-exo-trig

• . Notably, carbonylative amidation of a borylated aryl bromide to 26d proceeded well, where a Pd-catalyzed carbonylative amidation reaction would be plagued by undesired Suzuki coupling. Several secondary cyclic and acyclic amines, as well as primary amines were successfully employed as amine coupling

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

• unambiguous experimental evidence that the spin–vibronic coupling of 3CS/3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even if the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse

• intersystem crossing (rISC) is slow, without coupling with an approximate 3LE state. These studies are useful for an in-depth understanding of the photophysical mechanisms of the TADF emitters, as well as for molecular structure design of new electron donor–acceptor TADF emitters. Keywords: charge-transfer

• facilitated by the 3LE state, which shares a similar energy with the 3CS state, e.g., the so called spin–vibronic coupling effect, and as a result, the rISC is fast and efficient, which can result in significant TADF [13][27][28][29][30][31]. It was also proposed that vibration facilitates the ISC in the TADF