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

• are desired in light of growing environmental concerns. As a result, this review will explain various green chemistry approaches to synthesize N-substituted pyrroles. Although, Wynn [54] summarized several Clauson–Kaas protocols for the synthesis of N-substituted pyrrole derivatives. However, a

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• photocatalyst. Keywords: decarboxylative cyclization; DMAT; ergot alkaloids; photoredox catalysis; radicals; Introduction Visible-light photoredox catalysis is rapidly changing the way organic chemists approach the design and synthesis of molecules by offering new synthetic disconnection opportunities that

• of all ergot alkaloids, specifically the decarboxylative cyclization of DMAT, is still a puzzle even though a radical mechanism has been proposed (Figure 1a) [72][73]. Results and Discussion Herein, we propose that visible light irradiation of the cationic iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy

• compound 5 in hand, the required radical–radical coupling was investigated next, and some of the representative results are shown in Table S1 (see Supporting Information File 1). Irradiation from blue light-emitting diodes (LEDs) in the presence of 2 mol % of the photocatalyst [Ir(dF(CF3)ppy)2(dtbpy)]PF6

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

• ], Liu [35], and Yang [36] achieved similar transformations through visible-light photocatalysis. In addition, Guo [37][38] improved the protocol by using low-cost nickel and iron catalysts. However, most of these advancements mainly relied on the excellent redox potential manipulation of cyclic oxime

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• Adrian Saura-Sanmartin Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, 30100 Murcia, Spain 10.3762/bjoc.19.64 Abstract Light-responsive rotaxane-based solid-state materials are ideal scaffolds in order to develop smart materials due to the properties provided by the

• counterparts and/or macroscopic motion of the interlocked materials are achieved. Although further development is needed, these materials are envisioned as privileged scaffolds which will be used for different advanced applications in the area of molecular machinery. Keywords: light irradiation; light

• -responsive materials; mechanical bond; mechanically interlocked materials; rotaxanes; Introduction Light turns out to be a suitable and tailorable stimulus in order to develop materials showing improved functionalities, such as those of smart materials [1][2][3][4][5]. The characteristics of light which

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• experimental and ECD spectra (Figure 3 and Figure S26 in Supporting Information File 1). Consequently, the structure of 4 is defined and named 5-O-methyldaphnegiralin C1. Compound 7, a light yellow gum, has the molecular formula C16H28O3 (three degrees of unsaturation) as determined by its HRESIMS [M + H]+ ion

• at C-3 remains undetermined due to its long carbon chain. As a consequence, the structure of compound 7, named kronoponoid A, was determined to be as showed in Figure 1. Compound 8, a light yellow gum, possesses the molecular formula C17H30O3 (three degrees of unsaturation) deduced from its HRESIMS

• /z): [M + H]+ calcd for C21H25O5, 357.1697; found, 357.1680; 1H and 13C NMR data, see Table 3. Kronoponoid A (7): light yellow gum; [α]D25 +7.50 (c 0.40, MeOH); UV (MeOH) λmax, nm (log ε): 202 (3.68); HRESIMS (m/z): [M + H]+ calcd for C16H29O3, 269.2111; found, 269.2116 ; 1H and 13C NMR data, see

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

• proposed. Keywords: allomaltol; dihydrobenzo[h]pyrano[2,3-f]quinazolines; 6π-electrocyclization; photocyclization; pyrimidines; Introduction Photochemical processes involve absorption of UV light leading to the generation of molecules in the excited state and subsequent chemical transformations [1][2

• bridge fragments. At the same time, it is obvious that the ring size can significantly influence the photochemical properties. In this regard, it seemed interesting to obtain terarylenes with a six-membered bridge and to study their behavior under the action of UV light. Continuing our research in the

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• –Alder reaction, yielded the polyphenylene precursor 124 in an overall 12% yield. At last, a Scholl oxidation, mediated by DDQ and TfOH, gave the target NG 125 in a 6% yield. Due to the extremely large conjugated structure, compound 125 shows an extraordinary panchromatic light absorption capability (ε

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

• Oleksandr V. Kolomiiets,
• Alexander V. Tsygankov,
• Maryna N. Kornet,
• Aleksander A. Brazhko,
• Vladimir I. Musatov and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

• ], olprinon (cardiotonic agent for the treatment of acute heart failure) [18], GSK812397 (with anti-human immunodeficiency virus (HIV) properties) [19] (Figure 1). In light of the numerous viral epidemics and even pandemics, antiviral drugs that can inhibit the activity of proteins and enzymes encoded by

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• commercial antidepressants, anxiolytics and anticonvulsants, but also in reengineering for other applications. More recently, the potential of the dibenzo[b,f]azepine moiety in organic light emitting diodes and dye-sensitized solar cell dyes has been recognised, while catalysts and molecular organic

• ; synthesis; Introduction The dibenzo[b,f]azepine (1a) scaffold (Figure 1) is featured in commercial pharmaceuticals [1] and other lead compounds [2][3][4], ligands [5][6] and in materials science with possible applications in organic light emitting diodes (OLEDs) [7] and dye-sensitized solar cells (DSSCs

• )-10,11-dihydro-5H-dibenzo[b,f]azepine-2,8-diyl)bis(N,N-diphenylaniline) (9) exhibits properties suitable for the use in organic light emitting diodes [7] whereas dyes 10–12 were found suitable for the use in dye-sensitised solar cells (Figure 4) [8][9][10]. Though analogous dibenzo[b,f]oxepines 1b, with

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

• chemodivergent formation of C-3 ethoxycarbonylmethylated and hydroxyalkylated IPs under visible light using water or alcohol as the source of the oxygenated group under degassed conditions [22]. However, all these photochemical methods require the usage of a substantial amount of base, the preactivation with a

• ), light (entry 15) or acetylation agent (entry 16) failed to provide the desired product 4a, displaying the necessity of each component for developing the reaction. Substrate scope With suitable reaction conditions (Table 1, entry 12), we systematically investigated the scope of this acetoxymalonylation

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

• extensive attention owing to their potential applications in biomedicine, chemical sensing and as catalysts [1][2]. It is possible to regulate the formation and breakdown of supramolecular structures using external stimuli, such as pH, light, temperature, enzymes, and competing reagents [3][4]. Among these

• powders of CS-TPE exhibit a pale-yellow appearance under normal daylight conditions and emit intense green-blue light when exposed to UV irradiation (365 nm). This phenomenon differs greatly from the fluorescence properties of conventional ACQ fluorophores, which are typically nonfluorescent under UV

• (Zetasizer Nano ZS90) with a scattering angle of 90° and a wavelength of 636 nm. Partial 1H NMR spectra (400 MHz, CD3COOD/D2O, 25 °C) of (a) CS, (b) CS-TPE-2%, (c) CS-TPE-10%, and (d) CS-TPE-20%. (a) Optical images of CS-TPE under daylight (top) and 365 nm UV light (bottom) in the solid state; (b

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

• and Technology Alliance (BRTA), Paseo de Miramón 194, 20014, Donostia San Sebastián, Spain Basque Fdn Sci, Ikerbasque, 48013 Bilbao, Spain 10.3762/bjoc.19.42 Abstract A light-driven metal-free protocol for the synthesis of sulfone-containing indoles under mild conditions is reported. Specifically

• substrates [13][14][15][16][17][18]. In this approach, an electron acceptor substrate (“A”) and a donor molecule (“D”) interact to form a new aggregate defined as EDA complex (Figure 1a). Although the two molecular entities might not directly absorb visible light, the newly formed complex usually presents a

• charge transfer state which results in a bathochromic shift of the absorption towards the visible range [19][20]. Upon light irradiation, the EDA complex may undergo an intramolecular single-electron-transfer (SET) process to produce a radical ion pair (D•+, A•−). To avoid the occurrence of a back

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

• aromatic unit between base pairs, or by unspecific binding of the stacked dye along the polynucleotide backbone. In addition, CD measurements did not give unambiguous results since the polynucleotide and the dye absorbed UV light in the same wavelength region: the small hypochromic change of the ct-DNA

• the Edinburgh FS5 spectrometer. Quantum yields were measured for argon-purged solutions in sodium cacodylate buffer, pH 7.0, I = 0.05 mol dm−3, or pH 7.0, Ic = 0.05 mol dm−3 (λexc= 280 nm) at room temperature (25 °C) in a quartz cuvette of 10 mm path length; to avoid the scattering of incident light

• at the liquid–air interface, testing solutions with a 2 mL volume were used. Fluorescence and CD spectra were recorded using appropriate 1 cm path quartz cuvettes; UV–vis spectra were recorded in 1 cm path quartz cuvettes or using an immersion probe with 5 cm light path length. Isothermal titration

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

• shed light on future directions for further development in this field. Keywords: bicyclic alkenes; cascade; catalysis; domino; transition-metal-catalyzed; Introduction A well-orchestrated sequence of events – cascade, also known as domino, tandem, and sequential reactions, constitutes a fascinating

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• Co catalysis [165][166][167]. In 2022, Volla and co-workers reported the ortho-2,2,2-trifluoroethoxylation of benzamide using an N,O-bidentate directing group by merging Co- and visible light organophotocatalysis [168]. Palladium catalysis: In 2017, Ji, Li and co-workers reported a thorough study on

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• synthesize latrunculin analogues for chemical biology studies. In particular, our initial goal was to protect an inactive lactol-opened form of latrunculins, which could cyclize in vivo upon deprotection under a specific stimulus (light or enzyme, for instance) for biological applications. This challenge

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• conditions found by the authors gave the desired macrolide in only 30% yield together with the trans isomer, which was further isomerized to the cis-alkene during purification by column chromatography and light, being the first time that the trans isomer was reported (Scheme 19). Another strategy employed by

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

• well as optical properties. Moreover, the versatility of coumarin hybrids finds numerous applications including fluorescent brightening agents [16], optical sensors [17], organic light emitting diodes [18][19], light harvesting materials [20] and fluorescent probes in biological imaging [21]. Therefore

• . 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

• transfer quantum yield of 0.98. These conjugates could be useful in light-harvesting applications because of their optical characteristics. In 2008, Liu et al. [67] nicely demonstrated Cu(I)-catalyzed click chemistry for the synthesis of tetrakis(PM-β-CD)-modified zinc(II) porphyrin 166a and tetra(β-CD

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• should cause no interference with the measurement. Since interferences may also be caused by light scattering if the measurement is spectroscopic, centrifugation prior to measurement may be needed. However, it is good practice in any measurement to perform a control experiment to make certain that there

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

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• ], difenamizole [26], epirizole [27], rimonabant [28] etc. (Figure 1). Additionally, pyrazole derivatives hold a prominent position in the field of materials science as a result of their numerous applications in products like brightening agents [29], semiconductors [30], and organic light-emitting diodes [31

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• the treatment of CRC should be examined comprehensively and in detail, and each past study should shed light on possible future studies. In this study, 3D spheroid tumor models were studied to further elucidate the information we obtained in previous studies, and also mathematical release kinetic

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• revealed by X-ray single crystal structure analyses, and the NMR data are in agreement to the reported ones. In light of these findings, we herein correct the previous stereochemical assignments reported by one of us in the Beilstein J. Org. Chem. 2015, 11, 1922–1932 and the Monatsh. Chem. 2018, 149, 505

• inversion. For note, the 1H NMR spectrum of 5 revealed the presence of ca. 15% of the β-epimer 6, which could result from an incomplete stereospecificity of the substitution opening an alternative reaction path. Also in this case, the NMR data are then in agreement with the reported ones [18]. In light of

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

• analysis of lactam 19l. In order to shed light on the details of the reaction mechanism, we have performed carefully designed mechanistic studies which consist of experiments on the effect of β-silicon stabilization, the alkene geometry of the α,β-unsaturated acyl chloride reactants, and adventitious water

• in order to shed light on the mechanism and specific features of this transformation. Results and Discussion In the initial phase of our work, we used AgOTf as an anion-exchange agent in order to promote the desired aza-Nazarov cyclization [35]. The reaction between 3,4-dihydoisoquinoline (5a) and

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• is mediated by visible light irradiation. A wide range of substrates bearing different substituents and derived from ubiquitous carboxylic acids, including α-amino acids, were synthesized and examined under this very mild, efficient, and cost effective transition-metal-free synthetic method. These

• reported a Ru(bpy)3Cl2-catalyzed synthesis of N-Boc proline oxindole derivatives under visible-light assistance [47]. Therein, N-hydroxyphthalimide (NPhth) esters were utilized as alkyl radical precursors, which can be readily prepared from highly available carboxylic acids. In 2015, Cheng and co-workers

• disclosed a visible light-mediated radical tandem cyclization of N-arylacrylamides with N-(acyloxy)phthalimides to access 3,3-dialkylated oxindoles in the presence of [Ru(bpy)3Cl2]·6H2O [46]. However, these seminal methods remain limited by the need of noble-metal-based photocatalysts, excess additives and