Cyclodextrins as building blocks for new materials

• Miriana Kfoury and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2023, 19, 889–891, doi:10.3762/bjoc.19.66

• biocompatible. Thus, these supra-architectures have a multitude of uses in food, biomedicine, regenerative medicine, cosmetics, molecular electronics, polymer chemistry, gold recovery, gas absorption, depollution, biochemical material sciences, nanotechnology, self-healing materials, 3D printing, and so on [19

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

• , photoswitchable rotaxane-based materials have shown very interesting machine-like operation modes, highlighting the macroscopic transport of iodomethane drops along an inclined gold surface caused by light-triggered variations in the polarophobicity of interlocked fumaramide-based films [30]. Another application

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

• % yield via a gold/silver catalyst system (Scheme 27). 4 Oxidative C–C coupling Whereas oxidative C–C coupling precedes amination in the industrial route to 5H-dibenzo[b,f]azepine, oxidative C–C coupling may also be the final step in the construction of the dibenzo[b,f]heteropine skeleton. Comber and

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

•  56B) [103]. These complex natural compounds exhibit strong pharmacological activities like anti-inflammatory, antituberculosis, analgesic properties, etc. The key reaction steps included a highly stereoselective gold-catalyzed or thermally activated Cope rearrangement and a gold-catalyzed 6-endo-dig

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• the relative stereochemistry (Scheme 17) [108][109]. 6 Synthetic equivalents of vinyl carbenes in (2 + 1) cycloadditions: Au(I)-catalyzed generation of 1,4-dithiane-fused vinylcarbene species In 2007, Wang and co-workers reported a gold-catalyzed Parham-type 1,2-sulfur migration to generate in situ a

• use in intermolecular cycloadditions, as the putative gold(I)-coordinated intermediates like 112 are indeed quite similar to those expected to arise from dihydrodithiin alcohol 90 (see Scheme 19) [112]. However, our results with the simple 2-ethynyl-1,3-dithiolane (116) immediately showed that the

• expected allyl cation (3 + 2) cycloaddition reactivity is not operating under gold(I) catalysis, but instead it behaved as a reliable and quite stereoselective vinylgold carbenoid species, affording exclusively cyclopropanation products with a wide range of olefin substrates (Scheme 18c). The carbene-type

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• different times and the percent emergence of the liquid fraction was plotted vs time (see also Figure 1). Characterization of matrices: Scanning electron microscopy (SEM) of gold-sputter-coated samples was carried out using a Phenom Pro 739 microscope. Infrared analysis was carried out for the crushed

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• [98][99][100]. Preliminary biological screening indicates that members of this class are able to overcome multidrug resistance in vincristine resistant cells [98][99][100]. To access the common scaffold 188, the group relied on an intramolecular gold-photocatalyzed radical-mediated cyclization of an α

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• Conia-ene-type cyclization, classically considered as a reliable method for the construction of bridged bicyclic structures [41], was envisaged. However, using a gold(I) catalyst the desired 5-exo-dig cyclization failed and only a 6-endo-dig cyclization was observed. Thus, Hong et al. explored a Mn(III

Synthetic study toward the diterpenoid aberrarone

• Liang Shi,
• Zhiyu Gao,
• Yiqing Li,
• Yuanhao Dai,
• Yu Liu,
• Lili Shi and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2022, 18, 1625–1628, doi:10.3762/bjoc.18.173

• the 6-5-5 tricyclic skeleton includes the mediation of Nagata reagent for constructing the C1 all-carbon quaternary centers and gold-catalyzed cyclopentenone synthesis through C–H insertion. Keywords: aberrarone; C–H insertion; gold; Pauson–Khand; total synthesis; Introduction Marine natural

• were reported [30][31] and more recently, Carreira and co-workers reported [32] the first total synthesis of aberrarone through an impressive cascade reaction including a gold-catalyzed Nazarov cyclization, a cyclopropanation followed by intramolecular aldol reaction to forge the A, B and D rings

• one quaternary carbon stereocenter and 1,2-dikeone moiety, Nazarov cyclization [33] of 7 was proposed for synthesizing this challenging moiety. The corresponding precursor cyclopentenone 8 may be prepared from alkynone 9 through a gold-catalyzed C–H insertion [34]. Alkynone 9 could be achieved through

Formal total synthesis of macarpine via a Au(I)-catalyzed 6-endo-dig cycloisomerization strategy

• Jiayue Fu,
• Bingbing Li,
• Zefang Zhou,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2022, 18, 1589–1595, doi:10.3762/bjoc.18.169

• . The convergent synthetic strategies feature the utilization of Au(I)-catalyzed cycloisomerizations of a 1,5-enyne and alkynyl ketone substrates, which were prepared by Sonogashira coupling reactions. Keywords: benzo[c]phenanthridine alkaloids; 1,5-enyne; formal total synthesis; gold catalysis

• building blocks 5 and 8 in hand, ketone 9 was prepared via a palladium-catalyzed Sonogashira coupling reaction in a yield of 95%. The precursor 10 for the gold(I)-catalyzed [19][20][21][22][23][24] cycloisomerization was then synthesized by treating ketone 9 with sodium bis(trimethylsilyl)amide (NaHMDS

• ) and tert-butyldimethylsilyl chloride (TBSCl) (Scheme 5). To find the best cycloisomerization conditions, the 1,5-enyne substrate 10 was subjected to different reaction conditions as listed in Table 1. It was observed that [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]gold(I) chloride (IPrAuCl

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• showcasing innovative research regarding supramolecular catalysis using macrocyclic and acyclic hosts, as well as other molecular architectures such as self-assembled capsules and metallocages. In their contribution, Secchi and Cera [15] reported the synthesis of diphosphine gold(I) calix[6]arene complexes

• whose geometry, in low-polarity solvents, is controlled by the 1,2,3-alternate conformation of the calix[6]arene skeleton. These catalysts can tune the selectivity of the catalytic cycloisomerization of 1,6-enynes in response to the relative orientation of the coordinated gold(I) atom with respect to

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• oxidations of alcohols to aldehyes or ketones using gold nanoparticles in the presence of oxygen gas or atmospheric air was achieved by modifying the silica shell of nanostructured MagSilicaTM with gold nanoparticles (Scheme 12, case B). After heating these modified SPIONs in an electromagnetic field, a

Direct C–H amination reactions of arenes with N-hydroxyphthalimides catalyzed by cuprous bromide

• Dongming Zhang,
• Bin Lv,
• Pan Gao,
• Xiaodong Jia and
• Yu Yuan

Beilstein J. Org. Chem. 2022, 18, 647–652, doi:10.3762/bjoc.18.65

• applied in amination reactions [17][18][19][20][21][22][23][24]. Especially, N-hydroxyphthalimide can react with arenes directly in the presence of palladium [25] or gold [26] (Scheme 1, reactions 1 and 2). Recently, we found that iron catalyzes the amination of arenes with N-hydroxyphthalimide under air

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• . Transition-metal catalysts play an important role for the development of intricate pharmaceutical drugs. Although transition-metal catalysts based on rhodium, cobalt, and palladium have been intensively studied, gold catalysis has received encouraging attention only recently [67][68]. Since selectivity of

• gold-catalyzed reactions is still a concern, the catalytic transformation is often controlled by introducing a ligand as a first coordination sphere of the active gold species. In a supramolecular approach, introduction of the ligated gold complex inside a hollow cage may significantly improve the

• reactivity and selectivity because the cage provides a second coordination sphere around the catalyst thus controlling the catalytic reaction. This idea has been impressively demonstrated by Reek [69], Ballester [70], and Raymond [71], where a single gold-based catalytic unit is encapsulated inside a

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• catalyst (Table 1, entry 14) [60]. Other less common oxidizing agents have also been used for the oxidation of 2-methylnaphthalene (16) to produce menadione (10). Sulman and co-workers, for instance, achieved the oxidation of 10 using peracetic acid as oxidant in the presence of gold nanoparticles

• also reported the oxidation of 2-methylnaphthol (17) using molecular oxygen in the presence of gold nanoparticles as catalyst and the best yield of menadione (10) was obtained using 1.5% Au/TiO2 as catalyst (57%, Table 2, entry 9), while the best conversion of 17 was furnished using 1% Au/C-2 catalyst

• of 10 occurred in two steps and at high selectivity conversion rates when using AlF3-57 and MgF2-71 (Scheme 22A). The second proposal explored the reductive acetylation reaction of menadione (10) with acetic anhydride catalyzed by gold(III) deposited on the qualified metallic fluorides. The

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• -cd]indoles 21 from the intramolecular cyclization of Ugi adducts 20 in moderate to good yields and excellent chemo-, regio-, and diastereoselectivity (Scheme 7) [17]. Mechanistically, the reaction involves a tandem gold(I)-catalyzed dearomatization/ipso-cyclization/Michael addition sequence to

Diametric calix[6]arene-based phosphine gold(I) cavitands

• Gabriele Giovanardi,
• Andrea Secchi,
• Arturo Arduini and
• Gianpiero Cera

Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21

• polarity solvents, of a novel class of diametric phosphine gold(I) cavitands characterized by a 1,2,3-alternate geometry. Preliminary catalytic studies were performed on a model cycloisomerization of 1,6-enynes as a function of the relative orientation of the bonded gold(I) nuclei with respect to the

• macrocyclic cavity. Keywords: 1,2,3-alternate conformation; calix[6]arenes; gold(I) catalysis; phosphines; Introduction One of the latest challenges in supramolecular chemistry is the design and development of novel macrocyclic-based entities able to influence the catalytic activities of the metal center [1

• , calix[4]- [9][10][11][12][13] and resorcin[4]arene [14][15][16][17] are the most exploited cavitands due to their inherent limited flexibility and already proved their ability to control the catalytic activity of late-transition metals and particularly gold(I) catalysts [18][19][20][21][22][23][24][25

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• and detection at 220 nm. Preparative reverse-phase HPLC was performed by using Thermo Scientific Ultimate 3000 equipped with a Thermo Hypersil Gold (5 µm, 150 × 21.2 mm) column adpoting the following buffer systems: A: 0.1% TFA in water. B: 0.1% TFA in MeCN using a 10–90–90–10 vol % MeCN gradient (10

A tribute to Carsten Schmuck

• Jochen Niemeyer,
• Ivo Piantanida and
• Thomas Schrader

Beilstein J. Org. Chem. 2021, 17, 2795–2798, doi:10.3762/bjoc.17.190

• have become the gold standard for undergraduate teaching, so everyone is well-advised to read “The Schmuck” when diving into the world of (Organic) Chemistry for the first time. On top of all that, he also took on the task to write an updated version of the classical organic chemistry encyclopedia

GlycoBioinformatics

• Kiyoko F. Aoki-Kinoshita,
• Frédérique Lisacek,
• Niclas Karlsson,
• Daniel Kolarich and
• Nicolle H. Packer

Beilstein J. Org. Chem. 2021, 17, 2726–2728, doi:10.3762/bjoc.17.184

• , Switzerland Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Box 440, 40530 Gothenburg, Sweden Faculty of Health Sciences, Department of Life Sciences and Health, Pharmacy, Oslo Metropolitan University, 0167 Oslo, Norway Griffith University, Gold Coast Campus, Southport

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• concept by application to isolated reactions, while in the following section, examples of tandem reactions in total syntheses are given. Inspired by the direct ring expansion of 1-alkynylcyclobutanols to α-methylenecyclopentanones catalyzed by gold reported by Toste and co-workers [9], Kim et al

• derivative 28, which has a lower tendency for ring expansion. At room temperature, this substrate stopped at the hydrated intermediate 29, which could be isolated and remained intact when heated to 80 °C alone in 1,4-dioxane. Inclusion of the gold catalyst while heating, however, initiated the rearrangement

• to 30, confirming the importance of Au(I) in catalyzing both steps in the tandem reaction. Notably, this is the first time in the literature that α-ketol rearrangements have been initiated by a gold catalyst. Optimization revealed that the tandem reaction is best performed with Au(JohnPhos)SbF6 in

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• cost-effective drug. Due to its impressive antimicrobial activity and limited adverse effect metronidazole (1) has been considered as a “Gold Standard” antibiotic (Figure 1). However, to avoid the problem related to clinical resistance to this antimicrobial agent some novel and improved analogues of

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• non-specific protein absorption. Su et al. [40] investigated the effects of a protein corona on active and passive targeting using 20 different types of PEGylated gold nanoparticles, which were decorated with cyclic RGD (arginylglycylaspartic acid) peptides. As a result, the active targeting

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• gold(III) [43], iridium(III) [44][45], iron(III) [46], or bismuth(III) [47][48] were used as catalysts for the intermolecular hydroarylation of unactivated alkenes. Organic Brønsted acids were also used as catalysts in a smaller number of studies [49][50]. In this work, we searched for some organic

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138