N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• , indirubin, and isoindigo which can be regarded as blue, red, and yellow sugars, respectively. Review Indigo-N-glycosides (blue sugars) In 2002, Laatsch and Maskey reported the isolation of the akashins A, B and C, indigo-N-glycosides, from terrestric Streptomyces (Scheme 2) [17][18]. These natural products

• -glycoside 11a (Scheme 7) [20]. Debenzylation gave product 11b which was transformed to akashin A (11c) by reduction of the azide to the amine in the presence of propane-1,3-dithiol and subsequent debenzoylation. Akashin A was transformed to akashins B and C by acetylation and reaction with diacetyl

• -O-trimethylsilyl-ʟ-rhamnopyranose (4b) with TMSI gave intermediate A containing an anomeric iodide. Electrophilic addition of rhamnosyl iodide A to one of the two imino groups of 13 gave intermediate B. Another electrophilic addition of n-propyl mercaptane to the second imino group afforded

Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates

• Kento Iwai,
• Akari Hikasa,
• Kotaro Yoshioka,
• Shinki Tani,
• Kazuto Umezu and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238

• molecule on this cation, followed by tautomerism (path a). The intramolecular attack of an amide carbonyl on this cationic site in intermediate 10, leading to the formation of oxonium ion 11, is also possible (path b). After the addition of water, the formed hemiacetal 12 was hydrolyzed to give the

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• emission (green line, λex = 250 nm) spectra of 5 µM Tb.1 in 10 mM Tris-HCl buffer, pH 7.4, containing 5% DMSO. (a) Changes in the luminescence emission spectrum of 5 µM [Tb.1·3Cu]3+ upon the addition of Na2S (0–15 µM); spectra measured in 10 mM HEPES buffer (pH 7.4) with λex = 250 nm. (b) Change in

• luminescence intensity detected at 545 nm upon the addition of Na2S (n = 3). (a) Changes in the luminescence emission spectrum of 5 µM [Tb.1·3Cu]3+ upon the addition of Na2S (0–15 µM); spectra measured in 10 mM Tris-HCl buffer (pH 7.4) with λex = 250 nm. (b) Change in luminescence intensity detected at 545 nm

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• St., 344090 Rostov-on-Don, Russian Federation Clinical Laboratory Diagnostics Department, N. N. Burdenko Voronezh State Medical University, 10 Studencheskaya St., 394036 Voronezh, Russian Federation Gause Institute of New Antibiotics, 11 B. Pirogovskaya St., 119021 Moscow, Russian Federation Organic

• well as from intermediate 8a (∆G = +3.97 kcal/mol) is thermodynamically more favorable than for all other routes (path B). Fungal infections are a growing threat to public health, resulting in significant economic costs to healthcare systems [38][39]. One of the most common fungal diseases is invasive

• ]pyrimidines. Key correlations observed in the NOESY and HMBC spectra of the products 4d and 5d. Structures of imidazo[1,2-a]pyrimidines selected for docking and voriconazole selected for comparison. (A) Position of the (S)-isomer of compound 4e in the active site of CYP51 after molecular dockinga. (B

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• difluoromethyl enol ethers, which have the potential for further functionalization. Overview over difluoromethyl enol ether syntheses from acyclic and cyclic 1,3-diones (A), acyclic ketones (B), and cyclic ketones (C). Attempted difluoromethylation of 1a in solution. The reactions were performed on a 0.2 mmol

• scale. Method A: 2 (2.0 equiv), KFHF (4.0 equiv), CH2Cl2 (0.2 mL), H2O (0.2 mL), rt, 10 h; Method B: 2 (2.0 equiv), KOAc (4.0 equiv), CH2Cl2 (0.2 mL), H2O (0.2 mL), rt, 10 h. The yields were determined by 19F NMR spectroscopy using trifluoromethoxybenzene as the internal standard. Scope of ketones. The

• yields were determined by 1H NMR spectroscopy using 1,2-dichloroethane as the internal standard. In parentheses: yields after column chromatography (with product purities of ca. 90%). aWith CsCl. bWith KCl. Proposed mechanism (A) and mechanistic investigations (B and C). The yields were determined by 1H

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• one, may have slowed down the protodeboronation process, as substrates with electron-withdrawing groups are postulated to increase the Lewis acidity of the boronic acid, which may allow an increased incidence of protodeboronation to occur. It is also known that aryl–B(Pin) complexes have a greater

• octasubstituted 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP, 3). (B) Aim of this work, the arm extension of the meso-phenyl position of dodecasubstituted porphyrins. Substrates used for the investigations for the Suzuki–Miyaura coupling reactions. View of the molecular structure of compounds 26 (top left) and 27

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• generation by C60 and its derivatives [17][18][19]. The most important: upon the addition of PyBA to catC60-lip, the signal intensities of both types of ROS (1O2 and •OH) were decreased (Figure 5a(iii), b(iii), c(iv)). These results indicate that PyBA suppresses ROS generation by catC60-lip in liposome

• was taken into the ESR tube and ESR spectra were recorded at room temperature. (a) Chemical structure and schematic illustration of the charge-separated state of a triad molecule and (b) control of the membrane potential by the illuminated molecule with a favourable arrangement. (c) Strategy of the

• . (b) Effect of 1-pyrenebutyric acid (PyBA) addition at various concentrations to liposomes without catC60 and C60. The gel-to-liquid crystalline phase transition for 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes was observed at 25 °C. All the measurements were performed with liposome

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• reactions (Figure 1). Polycondensed heterocycles containing a uracil moiety have also been studied in recent years. For example, compound A exhibits antitumor and antimicrobial properties (Figure 2) [66][67]. Compounds A and B are used as starting materials for the synthesis of polyaromatic derivatives of

• other compounds with medicinal or photophysical properties [52][53][54][55]. Compounds A are related to the class of natural products known as coumestans, while B resembles flavins. While the medical potential of coumestans is still the subject of current research, interesting photocatalytic properties

• ; EIMS (70 eV) m/z (%): 352 (96, M+), 294 (28), 266 (67), 251 (14), 238 (30), 160 (100); HRESIMS-TOF(m/z): [M + H]+ calcd for C20H15F2N2O2, 353.1101; found, 353.1100. 5-(Benzo[b]thiophen-3-yl)-1,3-dimethyl-6-(p-tolylethynyl)pyrimidine-2,4(1H,3H)-dione (4i). Compound 4i was obtained as a brownish solid in

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• performance. In their contribution “Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs”, Moutayakine and Burke described a new synthetic route for the synthesis of 10,11-dihydro-5H-dibenzo[b,e][1,4]diazepinone (DBDAP

• -dihydro[1,3]thiazolo[4,5-b]pyridine derivatives that exhibited strong herbicidal activity against commercially significant grass weeds in preemergence greenhouse tests. The synthetic route for this new family of compounds was developed and optimized, involving several reaction steps, included Pd-catalyzed

• Suzuki couplings and the reduction of the thiazole moiety to 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a crucial intermediate, using BH3⋅NH3 and tris(pentafluorophenyl)borane as a Lewis acid, followed by treatment with formic acid. Gillie et al. reported the synthesis of a laterally fused N-heterocyclic

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• PL lifetime was measured using a Quantaurus-Tau C11367-34 fluorescence lifetime spectrometer (Hamamatsu Photonics, Japan). (a) Reported photophysics of diphenylacetylene after photoexcitation. (b) Our molecular design to suppress internal conversion. Relationship between the molecular structure of

• fluorinated diphenylacetylenes and photoluminescence (PL) color in their crystalline states. (a) PL spectra of the donor–π–acceptor (D–π–A)-type diphenylacetylene compounds 1a–g contained in a poly(methyl methacrylate) (PMMA) dispersion film. (b) Photographs of the PMMA dispersion films under ultraviolet (UV

• ) irradiation (λex = 365 nm). (c) A PL color diagram defined by the Commission Internationale de l'Eclairage (CIE). (a) PL spectra of PMMA dispersion films containing 1 wt % of blue fluorophore 1a and green–yellow fluorophore 1c in various weight ratios. (b) Photographs of the PMMA dispersion films under UV

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• , depicted by the purple points in Figure 1B. Results and Discussion The following nomenclature will be used during the volcano plot analysis: FX_LBLA_S1_S2 where X is the label of the family (1, 2, 3, 5, or 6), LB is the Lewis base considered (N or P), LA is the Lewis acid (in this particular study only B

• , fourteen FLP scaffolds have been evaluated (Figure 3), focussing specifically on N/B and P/B FLPs because of their widespread application in this field, especially considering the initial step involving CO2 capture [6][12][21]. Selection of the scaffolds and substituents Volcano plots were introduced to

• , families can be selected to cover a wide energy range. The obtained free energies of formation are presented in Figure S2 (Supporting Information File 1). The stabilities of the N/B adducts range from −9 to +48 kcal·mol−1, while the P/B adducts vary from +10 to +36 kcal·mol−1. The reliability of a volcano

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• Bhaskar B. Dhotare Seema V. Kanojia Chahna K. Sakhiya Amey Wadawale Dibakar Goswami Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai, PIN-400085, India NMIMS Sunandan Divatia School of Science, Vile-Parle, Mumbai-400056, India Chemistry Division, Bhabha Atomic Research Centre

• enolization of benzofuranone 3 in the presence of a base produced intermediate A. The latter reacted with hydroperoxide to form B with the concomitant generation of the radicals, which further reacted with intermediate B to form intermediate C. Finally, C is hydrolysed with the release of one molecule CO2 and

• two molecules 2-hydroxytetrahydrofuran to give the target product 4. One of the commercially important 2-hydroxybenzophenones, oxybenzone, is widely used as an ingredient in sunscreen lotions, due to its ability to absorb UV light, both in the UV-A and UV-B region [28][29]. However, oxybenzone, having

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• ., B and B’ here. The molecular ion and one of the fragment ions both increased by 14 Da, respectively, within the series. This suggests that A–F have the same core structure, but different chain lengths. Although the mass spectra showed small ions m/z 60 and 73 characteristic for aliphatic carboxylic

• procedures, NMR spectra. Acknowledgements We thank A. Faasen, R. Hartdegen, C. Hollowed, and B. Lawrence for the permission to access to snakes at the Bronx Zoo, New York. The photo in the graphical abstract was taken by Junkyardsparkle from wikipedia.org https://upload.wikimedia.org/wikipedia/commons/c/ca

Deciphering the mechanism of γ-cyclodextrin’s hydrophobic cavity hydration: an integrated experimental and theoretical study

• Stiliyana Pereva,
• Stefan Dobrev,
• Tsveta Sarafska,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2024, 20, 2635–2643, doi:10.3762/bjoc.20.221

• the other complexes only two options were modelled (Figure 2, n = 2–7, structures a and b). The first water molecule can bind to the narrow rim (n = 1; Figure 2, structures a–c) or the wide rim (n = 1; Figure 2, structures d and e). All attempts to position single water molecule in the cavity or near

• , structures a–c) suggest, the structures with a water molecule positioned at the narrow rim of γ-CD (n = 1; Figure 2, structures a–c) appeared to be the most stable ones. Isoenergetic structures b and c arise from initial structures with the water molecule positioned differently, in the middle of the CD

• cavity (b) and in the center of the upper rim plane. Therefore, the narrow rim with the H-bonded primary OH groups can be considered as a major attractor (anchor, hot spot) for the incoming water molecules. The identification of this hot spot location provides very useful information for modelling the γ

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

• Alfiya R. Gimadieva,
• Yuliya Z. Khazimullina,
• Aigiza A. Gilimkhanova and
• Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

• )sulfate ions, thus enabling activated A or B particles to attack the substrate molecule, resulting in the intermediate σ-complex C. A like particle B [Pc–Me–Oδ−–Oδ+–SO3−] has been previously described in [33]. The formation of particle B is possible via the interaction of the catalyst PcM with the SO52

• mixture to room temperature, concentrated H2SO4 was slowly added until pH 6–7 according to litmus paper and left standing for 12 h. The precipitated white crystals were filtered off, washed with water, and dried in air. Compound 2 yields are given in [13] and compound 5 yields are given in Table 1. b

• yields of compound 8 are given in Table 2. b) In a 150 mL three-neck flask equipped with a reflux condenser, a mechanical stirrer, a solution of 0.06 mol of pyridine in 20 mL of azeotropic solution of water and acetone (1:1) was slowly added to 20 mL of 24% NaOH solution, the reaction temperature was

Synthesis and cytotoxicity studies of novel N-arylbenzo[h]quinazolin-2-amines

• Battini Veeraiah,
• Kishore Ramineni,
• Dabbugoddu Brahmaiah,
• Nangunoori Sampath Kumar,
• Hélène Solhi,
• Rémy Le Guevel,
• Chada Raji Reddy,
• Frédéric Justaud and
• René Grée

Beilstein J. Org. Chem. 2024, 20, 2592–2598, doi:10.3762/bjoc.20.218

• Battini Veeraiah Kishore Ramineni Dabbugoddu Brahmaiah Nangunoori Sampath Kumar Helene Solhi Remy Le Guevel Chada Raji Reddy Frederic Justaud Rene Gree Anurag University, Ghatkesar, Hyderabad 500088, TS, India Chemveda Life Sciences India Pvt. Ltd., #B-11/1, IDA Uppal, Hyderabad-500039, Telangana

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• deprotonates to the anion B under action of DBU. Subsequent intramolecular cyclization at the double bond of pyranone fragment leads to the formation of spiro compound C. Next, opening of the dihydropyranone ring results in pyrrolidin-2-one D which further transformed to the salt of 3-acyltetronic acid E

Transition-metal-free synthesis of arylboronates via thermal generation of aryl radicals from triarylbismuthines in air

• Yuki Yamamoto,
• Yuki Konakazawa,
• Kohsuke Fujiwara and
• Akiya Ogawa

Beilstein J. Org. Chem. 2024, 20, 2577–2584, doi:10.3762/bjoc.20.216

• generated from triarylbismuthines by our developed methods would be successfully trapped by diboron to form a new C–B bond. In this study, we report a facile and versatile synthesis of arylboronates using triarylbismuthines as aryl radical sources under transition-metal-free and open-air conditions (Scheme

• the presence of TEMPO, the decomposition of 2 was sightly occurred, and almost all of 2 was recovered (see Supporting Information File 1). Based on the results, diboron 2 could also be activated via the thermal homolysis of the B–B bond in the presence of oxygen (air). Based on the results of the

• • would react with air to form pinB–O–Bpin and pinB–OH (path A). The corresponding arylboronates could also be formed via aryl radical trapping with pinB• generated by heating (pinB)2 in air (path B). Conclusion In this study, we have developed a novel method for the transition-metal-free synthesis of

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• assemblies, 2+-BF4− was further treated with NaPF6, LiB(C6F5)4, and NaPCCp for the ion-pair metathesis to afford ion pairs 2+-X− (X− = PF6−, B(C6F5)4−, and PCCp−) in 44–68% yields. The obtained ion pairs were characterized using 1H, 13C, and 19F nuclear magnetic resonance (NMR) and matrix-assisted laser

• orthogonal arrangement in comparison with the phenyl moieties in 1b+. Solid-state ion-pairing assemblies of the ion pairs 2+-X− (X− = Cl−, BF4−, PF6−, B(C6F5)4−, and PCCp−) were investigated by X-ray analysis of the orange rod-shaped single crystals, which were obtained by vapour diffusion using CHCl3/n

• -heptane for 2+-Cl−, 2+-BF4−, and 2+-PCCp−, CH2Cl2/n-heptane with small amounts of MeOH and toluene for 2+-PF6−, and toluene/n-hexane for 2+-B(C6F5)4− (Figure 3 and Figures S11–15 in Supporting Information File 1) [32]. In the single crystals, 2+ showed highly planar core structures with mean-plane

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• functionalized pyrimido[5,4-b]indoles due to its high functional group tolerance. Multiple examples were demonstrated with indole 1H-carboxamides linked to drug molecules or natural products at the R2 position. Additionally, an alkyl azide at the R2 position and an iodide at the R1 position were tolerated

• , due to the protonation of triticonazole, the participation of the protonated form in the overall reaction mechanism is also considered in pathway B (Scheme 21). Benzo[c][1,2]oxazines are useful scaffolds for the synthesis of natural products. In 2021, the Han group developed the electrochemical [4 + 2

• the DDQH• radical to generate a carbocation and DDQH−. In path B, the reaction involves direct hydride transfer to DDQ, forming DDQH− and a carbocation. In both pathways, the amine nucleophile captures the carbocation, resulting in the final amination product after losing a proton. Subsequently, DDQH

Visible-light-mediated flow protocol for Achmatowicz rearrangement

• Joachyutharayalu Oja,
• Sanjeev Kumar and
• Srihari Pabbaraja

Beilstein J. Org. Chem. 2024, 20, 2493–2499, doi:10.3762/bjoc.20.213

• ], spirulina [16], Ti(OiPr)4/t-BuOOH [17], VO(acac)2)/t-BuOOH [18], and enzymatic oxidation [19] etc., which may compromise the environmental benefits (Scheme 1a,b) and take longer reaction times. Alternatively, a new green pathway is necessary for the Achmatowicz reaction to be performed in a faster and safer

Machine learning-guided strategies for reaction conditions design and optimization

• Lung-Yi Chen and
• Yi-Pei Li

Beilstein J. Org. Chem. 2024, 20, 2476–2492, doi:10.3762/bjoc.20.212

• SMILES and are instead described using textual labels. A comparison of three types of reaction embedding methods: (A) descriptor-based, which use predefined features from reactants and products, (B) graph-based, which use neural networks to learn features from molecular graphs, and (C) text-based, which

HFIP as a versatile solvent in resorcin[n]arene synthesis

• Hormoz Khosravi,
• Valeria Stevens and
• Raúl Hernández Sánchez

Beilstein J. Org. Chem. 2024, 20, 2469–2475, doi:10.3762/bjoc.20.211

• described in the introduction (Scheme 1a and b) [56][58][59][63][66][80][84][85][86][87][88]. Furthermore, we successfully synthesized carboxylic acid-containing resorcin[4]arenes 1o–s employing HFIP under an optimized reaction time of 48 hours. Compounds 1o–s are reported here for the first time. Their

• translated to the formation of other macrocycles as long as they share a similar reaction mechanism. (a) Control experiment testing deiodination of 2-iodoresorcinol. (b) Molecular crystal structure of chlorinated resorcin[4]arenes 1h and 1i, and carboxylic acid-containing 1s at 100 K. Thermal ellipsoids are

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• in Scheme 2. Unfortunately, the substrates 8a,b displayed low reactivity due to their significantly higher oxidation potential compared to the excited photoredox catalysts (>2.5 V vs SCE) [49]. However, other derivatives exhibited a satisfactory product yield ranging from moderate to good. Substrate

• attack the radical cation A, giving the bicyclic radical intermediate B. Amide is an ambident nucleophile, and oxygen attack of radical cation A is also conceivable to give the corresponding imidate [28]. In our reaction, O-addition is disfavored due to the formation of an unsaturated four-membered ring

• vs SCE) [60][61] is sufficient to oxidize the radical form of IV (PC•/PC+ = −0.57 V vs SCE) [55][56]. Finally, PhS– is protonated and HAT from thiophenol to B furnishes the final product, closing the HAT cycle. Additionally, lutidine acts as a proton shuttle between the lactam NH unit and