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

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

• 54, 10000 Zagreb, Croatia Laboratory for the Computational Design and Synthesis of Functional Materials, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia Laboratory for Physical Chemistry and Corrosion, Department of Chemistry and

• Synthesis The phenanthridine derivative of the amino acid alanine (Phen-AA) has been prepared according to the procedure described earlier [19]. Phen-AA was deprotected under acidic conditions (TFA–H2O) at room temperature for 20 hours. The amide coupling reaction was performed in anhydrous acetonitrile

• , this result could lead to the development of new probes based on pyrene–phenanthridine chromophores that can switch fluorescence signals on/off upon binding to biomacromolecules. Experimental Synthesis The phenanthridine derivative of alanine amino acid (Phen-AA) has been prepared according to the

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• ]. Therefore, as relevant building blocks, tremendous efforts have been made to develop reliable methods for their synthesis. Transition-metal-catalyzed cyclopropanation of alkenes with trifluoromethyldiazoalkanes is a commonly used synthetic strategy for the construction of trifluoromethylcyclopropanes

• , the synthesis of difluoromethylcyclopropanes utilizing difluoromethyldiazo reagents remains rather unexplored. Nevertheless, some difluorocarbene reagents, including HCF2CH(N2) [32], Ph2S+CH2CF2H TfO− [33], and difluoroacetaldehyde N-triftosylhydrazone (DFHZTfs) [34], have been developed (Scheme 1B

• fluorinated diazo compounds might be rationalized by their low accessibility and high volatility [44]. As a part of our continuing investigations in fluorinated carbene chemistry [45][46][47][48][49], we hypothesized that the synthesis of cyclopropanes with geminal trifluoromethyl and

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

• -catalyzed domino reactions of strained bicyclic alkenes, including both homo- and heterobicyclic alkenes. These compounds are important synthons in organic synthesis, providing an important platform for the construction of biologically/medicinally significant compounds which bear multiple stereocenters. The

• review has been divided according to the metal used in the reaction. An overview of the substrate scope, reaction conditions, and their potential applications in organic synthesis is discussed. A comprehensive outlook on the reactivity paradigms of homo- and heterobicyclic alkenes is discussed and should

• branch of organic chemistry dedicated to the synthesis of highly functionalized products through sequential transformations in a single reaction. Classically, a domino reaction has been defined by Tietze as a reaction involving two or more bond-forming transformations that take place under the same

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• ; Introduction Transannular cycloaddition reactions (TCRs) are useful for the synthesis of complex natural products and other biologically active compounds with high efficiency and stereoselectivity [1][2][3][4]. There are several different ways in which TCRs can occur, depending on the nature of the starting

Total synthesis: an enabling science

• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 474–476, doi:10.3762/bjoc.19.36

• Bastien Nay Laboratoire de Synthèse Organique, École Polytechnique, CNRS, ENSTA, Institut Polytechnique de Paris, 91128 Palaiseau, France 10.3762/bjoc.19.36 Keywords: chemical complexity; natural products; synthetic methodologies; total synthesis; Total synthesis is a topic strongly related to

• synthetic methodology developments and to natural product isolation or biosynthesis. Thus, thematic issues dealing with total synthesis in the Beilstein Journal of Organic Chemistry have naturally been published in these fields, such as "Transition-metal and organocatalysis in natural product synthesis

• " (edited by D. Chen and D. Ma) [1] or "Natural products in synthesis and biosynthesis" (edited twice by J. Dickschat) [2][3]. Previously, the early thematic issue "Indolizidines and quinolizidines: natural products and beyond" (edited by J. P. Michael) from 2007 [4] displayed some of the very first total

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

• Louis Monsigny Floriane Doche Tatiana Besset Normandie University, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000 Rouen, France 10.3762/bjoc.19.35 Abstract The last decade has witnessed the emergence of innovative synthetic tools for the synthesis of fluorinated molecules. Among these

• retrosynthetic disconnections. In this context, a strong interest from the scientific community was shown towards the challenging synthesis of fluorinated molecules by transition-metal-catalyzed C–H bond activation [44][45][46][47][48][49][50], allowing the functionalization of complex molecules and even for

• late-stage functionalization strategy [51][52][53] for the synthesis of natural products [42][54][55][56][57][58][59]. The goal of this review is to highlight and discuss the recent approaches for the synthesis of fluorinated derivatives by the direct incorporation of a fluorinated group of XRF type

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• , Germany 10.3762/bjoc.19.34 Abstract A protocol for the mechanochemical synthesis of copper(I)/N-heterocyclic carbene complexes using cheap and readily available K3PO4 as base has been developed. This method employing a ball mill is amenable to typical simple copper(I)/NHC complexes but also to a

• been shown to be active in a variety of reduction/hydrogenation transformations employing dihydrogen as terminal reducing agent. Keywords: ball mill; bifunctional catalysis; catalytic hydrogenations; copper; mechanochemical synthesis; N-heterocyclic carbenes; Introduction Prominent goals of green

• focus has seldomly been on the preparative methods to access the required catalysts themselves. As case in point, we decided to re-investigate the synthesis of copper(I)/N-heterocyclic carbene (NHC) complexes, which are broadly applicable catalysts for a wide variety of transformations [4][5][6]. While

Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C

• Karolina Wątroba,
• Małgorzata Pawełczak and
• Marcin Kaźmierczak

Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33

• . The reactions should proceed with high yields, and any byproducts should be easily removeable. Results and Discussion Dipeptide analogues of α- and β-fluorinated aminophosphonates 5 and 7 were obtained from the corresponding ʟ-amino acids [23][24] 1. In the key step of the synthesis fluorine was

• result of the reactions carried out, the dipeptide analogues of α- and β-fluorinated aminophosphonic acids 8 and 10 were obtained. All the samples were solids, with very poor solubility in water and organic solvents such as DMSO and MeOH. The final step of the synthesis was the reaction of the resulting

• of more effective fluorinated inhibitors of cathepsin C in our laboratory. Dixon plot for the hydrolysis of Gly-Phe-pNA substrate catalyzed by bovine cathepsin C in the presence of 9b (T = 37 °C, pH 5.0). Synthetic strategy towards 5 and 7. Synthesis of 9 and 11. (a) R = -CH3; (b) R = -CH(CH3)2; (c

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

• , France 10.3762/bjoc.19.32 Abstract Latrunculins are marine toxins used in cell biology to block actin polymerization. The development of new synthetic strategies and methods for their synthesis is thus important in order to improve, modulate or control this biological value. The total syntheses found in

• analogue synthesis, starting from (+)-β-citronellene. Key stereoselective transformations involve an asymmetric Krische allylation, an aldol reaction under 1,5-anti stereocontrol, and a Tishchenko–Evans reduction accompanied by a peculiar ester transposition, allowing to install key stereogenic centers of

• the natural products. Keywords: allylation; aldol reaction; latrunculins; stereocontrol; total synthesis; Introduction Latrunculins constitute a class of marine polyketide natural products isolated from Sponges like Negombata (= Latrunculia) magnifica [1][2]. They are characterized by the presence

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

• called cyclic diaryl ether heptanoids (DAEH). This review is intended to highlight the structure elucidation, biosynthesis, and biological activity of these compounds as well as the use of different strategies for their synthesis. Keywords: combretastatin D; corniculatolide; isocorniculatolide

• macrocycles and their synthesis finds several examples described in the literature and has already been the subject of review articles [2][3][4]. More recently, cyclic diaryl ether heptanoids (DAEH) [5], another class of macrocycles has been attracting attention not only because of their structural and

• characterized as an oxa[1.7]meta-paracyclophane framework. In the literature we can find reports about the isolation/synthesis of combretastatins D and their analogues which showed different biological activities, e.g., antineoplastic, anti-inflammatory, and α-glucosidase inhibition [13][14][15]. The presence