Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• years ago, the concept became increasingly accepted and popular only by the last decade of the last century [2][3]. Nowadays, organocatalysis is especially applied to asymmetric synthesis and a huge number of organocatalysts has been introduced in last three decades for the asymmetric synthesis of

• -substituted indoles which effectively attacked the electrophile through the C2 position. The reaction was even compatible with pyrroles (Scheme 7a). The utility of this methodology was successfully demonstrated by the synthesis of product 23a, the key intermediate of natural product (+)-trigonoliimine (Scheme

• substitutents. Excellent dia- and enantioselective synthesis of the products were caused by a chiral environment induced in the transition state through a dual H-bonding interaction between both the substrates and catalyst. In addition, π–π stacking between the aromatic moieties in both reagents brought more

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

• compounds. As a result, this review describes the use of various eco-friendly greener protocols to synthesize N-substituted pyrroles. This synthesis involves the reaction of various aliphatic/aromatic primary amines, and sulfonyl primary amines with 2,5-dimethoxytetrahydrofuran in the presence of numerous

• acid catalysts and transition metal catalysts. The goal of this review is to summarize the synthesis of various N-substituted pyrrole derivatives using a modified Clauson–Kaas reaction under diverse conventional and greener reaction conditions. Keywords: catalyst; Clauson–Kaas pyrrole synthesis; 2,5

• -dimethoxytetrahydrofuran; green synthesis; microwave-assisted reaction; N-substituted pyrrole; Introduction Heterocyclic compounds are the most explored molecules in organic chemistry in terms of their synthesis and various applications. Among the diverse heterocyclic compounds, N-containing heterocycles are found in

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

• accomplish by more conventional procedures, enables the synthesis of ergot alkaloid precursors. In addition, this work describes a mild, environmentally friendly method to activate, reductively and oxidatively, natural carboxylic acids for decarboxylative C–C bond formation by exploiting the same

• 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

• ground state catalyst [21][22][23][24][25][26]. While early research has focused on methods for the functionalization of relatively simple hydrocarbons [27][28][29][30], developments in photoredox catalysis have gained traction recently as a viable strategy for the total synthesis of natural products [31

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

• thiazole or thiazoline substituent, compounds 2–6 have not been reported before according to literature searches. Compound 1 was already described as an intermediate in the chemical total synthesis of micacocidin [35], but has not been isolated from a natural source before. Conclusion In summary, six

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

• the construction of a range of δ-olefin-containing aliphatic nitriles with (E)-configuration selectivity. This new method features wide substrate scope, mild conditions, and direct N–O activation. Keywords: direct N–O activation; E-selectivity; nitrile synthesis; ring-opening cross-coupling; sulfuryl

• of novel synthetic methods and strategies toward nitrile group construction continues to be a focus for synthetic chemists. The cross-coupling reactions of C–C bonds catalyzed by transition-metal complexes play a crucial role in modern organic synthesis, as they make it feasible to synthesize complex

• structures from available components [11][12][13]. Indeed, the formation of C(sp2)–C(sp3) bonds by cross-coupling has developed rapidly in recent years [14][15][16], but it still remains less advanced than the synthesis of C(sp2)–C(sp2) bonds [17][18]. This is attributed to the electron-richness of the C(sp3

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

• ). These structural features enable the construction of a five-membered ring upon treatment with alkenes [9], diazo compounds (reaction g) [10], and nitriles [11]. Several approaches are available for the synthesis of cyclopropanedicarboxylates 1a, which consist of three steps: 1) conjugate addition, 2

• 3b used in only three cases [12][13][19], to the best of our knowledge. Extending beyond Scheme 2, only two syntheses of nitrocyclopropanes containing cyclic keto esters or diketones have been reported [20][21]. These findings indicate that the synthesis of nitrocyclopropanes with an acyl group is

• quite difficult, although they would be very useful in synthetic chemistry, if available. In this study, we investigated the synthesis of nitrocyclopropanes using keto esters 3c–f and diketones 3b and 3g instead of diester 3a as the starting 1,3-dicarbonyl compounds. Results and Discussion We commenced

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• its applications in the total syntheses of complex natural products and other molecules of biological relevance [13][14]. Acylimidazoles proved to be versatile building blocks broadly applicable in asymmetric catalysis and organic synthesis. Today, acylimidazoles are used as ester/amide surrogates

• , because of their particular chemical and physical properties [15]. In addition to ester/amide synthesis, enoyl imidazolides were developed as excellent Michael acceptors. Acylimidazoles are unique electrophiles that demonstrate moderate reactivity, relatively high stability, chemical selectivity, and high

• solubility in water. Among exceptional properties belongs to easy post-transformation of acylimidazoles to common carbonyl analogs. These tunable properties allow the use of acylimidazoles in chemical biology research, which includes chemical synthesis of proteins/peptides, structure analysis, and functional

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• of several methods for the synthesis of functionalized pyridines or their integration into an organic molecule, new methodologies for the direct functionalization of pyridine scaffolds have been developed during the past two decades. In addition, transition-metal-catalyzed C–H functionalization and

• materials [1][2][3][4][5][6][7][8][9][10]. Due to its different characteristics such as basicity, stability, water solubility, small molecular size, and ability to form hydrogen bonds, pyridine continues to be a suitable moiety in organic synthesis. In addition, it has been observed that pyridine rings

• serve as bioisostere for aromatic rings, amines, amides, and N-containing heterocycles. Due to the aforementioned qualities, numerous U.S. FDA-approved medications have pyridine scaffolds in their molecules (Figure 1). In this context, the synthesis of the pyridine motif is always there in trend. Many

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• thiazole synthesis and elimination to nitriles) were identified. The key factor that enables the successful Eschenmoser coupling reaction involves the optimum balance in acidity of nitrogen and carbon atoms of the intermediary α-thioiminium salts. Keywords: Eschenmoser coupling reaction; Hantzsch thiazole

• synthesis; isoquinolin-4-ones; primary thioamides; structure–reactivity relationships; Introduction During several past years, we have developed [1][2] a novel synthetic approach toward (Z)-3-[amino(phenyl/methyl)methylidene]-1,3-dihydro-2H-indol-2-ones and have demonstrated [3][4] its application

• potential in the synthesis of various tyrosine kinase inhibitors, including hesperadin and the approved drug nintedanib. The key step of the synthesis involves the Eschenmoser coupling reaction (ECR) between a substituted 3-bromooxindole 1 and appropriate primary, secondary or tertiary thioamides which

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• have developed a new convenient protocol for the synthesis of 3-sulfonyl-substituted quinolines (sulfonamides and sulfones). The approach is based on a Knoevenagel condensation/aza-Wittig reaction cascade involving o-azidobenzaldehydes and ketosulfonamides or ketosulfones as key building blocks. The

• synthesis of quinoline-3-sulfonyl chlorides which are the most common reagents for their preparation. As a possible solution, the approach to the heterocyclic core construction from a sulfonamide-containing building block may be considered. In turn, diversely substituted quinoline-3-sulfones are available

• . While the ortho-amino carbonyl reagents are not always easily accessible and sometimes unstable (e.g., aminoaldehydes), both o-azidoaldehydes [58][59][60][61][62][63][64][65] and o-azidoketones [66][67][68][69] have been proved to be appropriate substrates for quinoline derivatives synthesis. Recently

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

• method for the synthesis of pyrimidines containing an allomaltol unit. The suggested approach is based on the reaction of 2-(1-(dimethylamino)-3-oxo-3-arylprop-1-en-2-yl)-3-hydroxy-6-methyl-4H-pyran-4-ones with cyanamide. The photochemical behavior of the obtained pyrimidines was investigated. It was

• [h]pyrano[2,3-f]quinazolines were confirmed by X-ray diffraction analysis. Based on the performed studies, a two-stage telescopic method for the synthesis of polyaromatic benzo[h]pyrano[2,3-f]quinazolines including the initial photocyclization of the starting pyrimidines and the final dehydration was

• developed for this reaction, allowing for the synthesis of pyrimidines 9 containing an allomaltol unit in good yields (Scheme 2). The process is of a general nature and is suitable for the synthesis of various target products 9 with electron-rich or deficient substituents. The plausible reaction mechanism

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• synthesis of synthetically useful N-arylsulfonylimines from N-(arylsulfonyl)benzylamines using K2S2O8 in the presence of pyridine as a base is reported herein. In addition, a “one-pot” tandem synthesis of pharmaceutically relevant N-heterocycles by the reaction of N-arylsulfonylimines, generated in situ

• their unique stability, defined reactivity, and versatility in organic synthesis [2]. Leveraging their electron-deficient nature, N-arylsulfonylimines are widely used in organic transformations including nucleophilic addition, cycloaddition, imino-aldol reaction, ene reactions, aza-Friedel–Crafts

• reactions, and C–H functionalizations ([3] and references therein), leading to the synthesis of diverse nitrogen heterocycles of pharmaceutical relevance [4]. The traditional synthetic method for the preparation of N-arylsulfonylimines, similar to the preparation of N-arylimines, is based on the

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• from operators or the equipment can have disastrous consequences. Because the large headspace of batch reactor aggravates these safety risks, the use of O2 in batch manufacturing is very limited [14]. Recently, continuous flow synthesis has recently been studied as a way to mitigate the safety risks

• ], and its screening results can be transferred to obtain a wide variety of benzaldehydes from benzyl alcohols. The screening was conducted under batch conditions. Toward its application to continuous-flow synthesis, we considered the description of the reaction mixture as well as the reaction rate

• equiv at 80°C, the reaction time was significantly prolonged, which is not suitable for the flow synthesis (Table 2, entry 7). Based on these findings, entry 6 was considered to be the optimal reaction conditions, and the application to flow synthesis using the honeycomb reactor was tried under these

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

• nanomaterials, the design, and construction of chiral nanographenes is a hot topic recently. As a classic nanographene unit, hexa-peri-hexabenzocoronene generally serves as the building block for nanographene synthesis. This review summarizes the representative examples of hexa-peri-hexabenzocoronene-based

• on representative examples of HBC-based chiral molecular NGs. All the examples in the context can be treated either as HBC-like monomers, or HBC-based dimers, trimers, tetramers, or oligomers. The synthesis of HBC is shown in Scheme 1. Pioneered by Scholl [30] and Clar [31] and further developed by

• precursors. Review seco-HBC-based chiral NGs In the HBC synthesis, a small fraction of a partially cyclodehydrogenated intermediate was indeed isolated during the conversion of hexaphenylbenzene to HBC [32]. Conceptually, the partially ring-closed intermediate by cutting one C–C bond of HBC can be treated as

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

• attention to another isocyanide multicomponent reaction – the Ugi reaction [21], which is one of the most important methods for the synthesis not only of peptidomimetics but also of other types of complex organic compounds. The presence of several diversity points and modification of starting components for

• carbonyl component was proposed, but these aldehydes did not have the structure of imidazo[1,2-a]pyridine. Interestingly, in 2019 [1], the synthesis of the amine component using GBB-3CR and the modification of the imidazo-pyrimidine scaffold by a peptidomimetic chain was carried out using the Ugi reaction

• (Scheme 2). It is obvious that the exploration of the possibility to create hybrid molecules by combining GBB-3CR and Ugi is successful, so one of the promising areas is to increase the diversity of relevant compounds using substituted aminopyridines in GBB-3CR and the synthesis of new peptidomimetics

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• , sulfonamides and aryltrifluoroborates is described. This process provides modular access to the important α-arylglycine motif in moderate to good yields and enantioselectivies. The formed α-arylglycine products constitute useful building blocks for the synthesis of peptides or arylglycine-containing natural

• , e.g., the antiplatelet drug clopidogrel [7] or the β-lactam antibiotic amoxicillin [8] (Figure 1). Therefore, the chemical synthesis of α-aryglycines has received considerable attention. Among the different methods introduced over time, multicomponent reactions utilizing an in situ generated reactive

• situ generation of reactive imine species, we have disclosed iron- and bismuth-catalyzed three-component reactions for the synthesis of α-arylglycines [14][15][16], in which the arylboronic acid could be replaced with an electron-rich (hetero)arene as nucleophile. In parallel, we have developed

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

• ; 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

• excellent neuroprotective properties for the treatment of Parkinson’s disease in rat models (Figure 5) [26]. Unfortunately, the promising preclinical studies of 19 could not be replicated in human trials [27]. For more details on the early synthesis of dibenzo[b,f]azepine (1a), the extensive review prepared

• heteroatoms (e.g., O, N, S, P, B and Si) in the heterocyclic ring result in analogues of dibenzo[b,f]azepines and -oxepines. This group of compounds will thus be broadly referred to as dibenzo[b,f]heteropines (1). The first section of this review will cover the synthesis of dibenzo[b,f]heteropines (1) and

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• /bjoc.19.50 Abstract Phostams, phostones, and phostines are a series of 1,2-azaphosphaheterocycle and 1,2-oxaphosphaheterocycle 2-oxide derivatives. They are phosphorus analogues of lactams and lactones and important biologically active compounds. The strategies for the synthesis of medium and large

• phostine derivatives, less attention has been paid to the synthesis of medium and large phostam, phostone, and phostine derivatives. They are also biologically active compounds, such as inhibitors of the human farnesyl pyrophosphate synthase [21][22], antitumor agents [23], and hapten for the production of

• the catalytic antibody [24]. They are also potential chiral ligands in asymmetric catalysis [25] (Figure 1). Cyclizations and annulations are two major strategies for the synthesis of medium and large phostam, phostone, and phostine derivatives. The cyclizations have been applied in the construction

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• , which exploit the carbon-rich nature, porous framework, and expanded π-electron system of these compounds [11]. And this is not a complete list. Recently, we reported on the synthesis of 1,4-diaryl-1,3-butadiynes 1–4 based on the “proton sponge” [1,8-bis(dimethylamino)naphthalene, DMAN] (Figure 1) [15

• ]. In the present work we describe the synthesis of a new family of proton sponge-based butadiynes 5 bearing arylethynyl substituents of different electronic nature. Oligomers 5 having electron-withdrawing groups on the aryl termini are interesting as push–pull A–π–D–π–D–π–A systems, whereas the

• us to undertake the current study. X-ray crystallography, UV–vis spectroscopy and cyclic voltammetry were applied to analyze the extent of π-electron conjugation and the efficiency of the particular donor–acceptor conjugation path in chromophores 5. Results and Discussion Synthesis The target

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• anticonvulsant agents had been developed based on PBTA derivatives (Figure 1) [2]. In addition, series of PBTAs (Figure 1) were found to exhibit antibacterial, antifungal, antioxidant, and cytotoxic activities [3][4]. Several strategies have been developed for the synthesis of PBTA derivatives [2][3][4][5][6][7

•  4). Results and Discussion It is known that [e]-fused 1H-pyrrole-2,3-diones (FPDs) (Figure 2) are versatile synthetic platforms enabling the synthesis of numerous heterocyclic species [33][34][35][36]. They are polyelectrophilic compounds, bearing five electrophilic centers, whose reactivity

• 17 as an undesired process during the synthesis of APBTTs 1. Reaction of APBTT 1a with methanol (2a) in different solvents.a Reaction of APBTT 1a with benzylamine in different solvents.a Reaction of APBTT 1a with aniline (11a) in different solvents.a Supporting Information Supporting Information

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

• on TBTQ-C6/CS-TPE supra-amphiphile, which may have potential applications in oral drug delivery materials and biomarkers. Results and Discussion Synthesis and characterization of CS-TPE. The host molecule TBTQ-C6 was synthesized as reported in our previously reported method [16]. Three CS-TPE

• reported procedures [16][23]. The 1H NMR spectra were recorded by use of a Bruker AV 400 spectrometer in D2O and CDCl3. Synthesis of CS-TPE. The TPE-CHO [23] (2 mol %, 10 mol %, and 20 mol %) solution in THF (20 mL) was added to the CS (143.1 mg, 0.9 mmol) solution in 1% glacial acetic acid (30 mL), and

• μg/mL, [TBTQ-C6/CS-TPE-10%] = 68 μg/mL, [TBTQ-C6 /CS-TPE-20%] = 60 μg/mL). (a) Synthesis route to CS-TPE. (b) Structure of TBTQ-C6. (c) Construction of TBTQ-C6/CS-TPE supramolecular nanoparticles and their pH-responsive behaviors. Supporting Information Supporting Information File 22: Solid-state CP

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• . Short information on applications in total synthesis is also given. Keywords: asymmetric catalysis; conjugate addition; electrophile; enolate; tandem reaction; Introduction The formation of complex chiral molecules is a crucial task of organic synthesis that enables the synthesis of pharmaceuticals

• synthesis of enantiomerically enriched cyclobutanes 77 [52]. Their strategy employed a three-component process in which tert-butyl (E)-2-diazo-5-arylpent-4-enoates 74 were treated with the chiral rhodium catalyst C1 to provide enantiomerically enriched bicyclobutanes 75. These highly strained compounds then

• formylation products. The methodology was later exploited in the expedient synthesis of the Taxol core (Scheme 34) [71]. Tandem conjugate borylations and silylations Chiral organoboron compounds are well-known synthetic building blocks with diverse possibilities for subsequent derivatization (e.g., oxidation

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• well as monomers for materials science [9][10][11][12][13][14][15]. In this context, their functionalization is fundamental to further improve their inclusion in fine organic synthesis and industrial processes. For this reason, in recent years, innovative protocols for the formation of new bonds on

• synthesis has increased dramatically and has rapidly become a routine tool for classical synthesis [26][27][28][29]. In particular, many efforts have been devoted to the development of flow alternatives for transition-metal-catalyzed cross-couplings [30] and for some C–H functionalizations [31

• (triethoxysilyl)ethyl)phosphine L1 or triphenylphosphine [40][41][42]. Their synthesis, well-described in the literature, is detailed in Supporting Information File 1 (pp. S3–S6). Moreover, a kinetic study carried out in batch in the presence of the [Ru3(CO)11(L1)] (comp1), [Ru3(CO)10(L1)2] (comp2) or [Ru3(CO)9

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

• ) and carbon–heteroatom (C–X) bonds has been and still is a central topic in organic synthesis [1][2]. Historically, organic chemists have extensively relied on the use of noble-metal-based catalysts (e.g., Pd, Rh, Ir, among others) to achieve such type of functionalization [3][4][5]. However, reliance

• -iodosulfones and DABCO, that are able to produce reactive C-centered radicals under mild reaction conditions. (a) Exploitation of an EDA complex in organic synthesis. (b) This work: use of halogen-bonded complexes to photochemically initiate the C–H alkylation of indoles 1 with iodosulfones 2. Optical

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

• complex. Solubility of the t-Bu-containing ligand and its Schiff base complexes is increased, facilitating scaling-up the reaction procedure and isolation of the functionalized amino acid. Keywords: asymmetric synthesis; chiral auxiliaries; cysteine derivatives; Ni–Schiff base complexes; voltammetry

• testing; Introduction Asymmetric synthesis of functionalized amino acids is a subject of intense research because these compounds are of great demand for pharmaceutical industry, health care, and food production [1][2][3]. Various approaches to enantiomerically enriched amino acids have been developed

• base chiral template is a fairly versatile “tool” that can be adapted to a specific task. A relatively new approach to functionalization of amino acids is a combination of a stereoselective synthesis in a metal-coordination environment with electrochemical activation [31]. It increases the reactivity