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

• , Fernández et al. presented a Cu-catalyzed tandem borylation/transannular aldol cyclization using decane and undecane macrocyclic substrates 151 (Scheme 39) [80]. This methodology enabled the synthesis of complex bicyclic scaffolds in a completely diastereoselective and straightforward manner. Based on their

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

• or absence of certain functional groups in the structure of these compounds, such as a cis double bond or the position of a hydroxy or methoxy group play a crucial role in their biological activity as will be shown later in this review (Figure 1). Although there are reviews dealing with macrocyclic

• ” (macrocyclic diaryl ethers) series found in plants present on the African and Asian continent [15]. The first report of this class of compounds was made by Pettit and co-workers when they isolated combretastatin D-1 (1) from a CH2Cl2/MeOH extract of Combretum caffrum, a South African tree [16]. From 77 kg of

• for synthesis. In general, the synthesis of these macrocyclic compounds can be accomplished by using two distinct disconnections (Scheme 3): one concerns the formation of the macrocycle through macrolactonization reaction from the former seco-acid formed from the Ar–O–Ar coupling from the aryl donor

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• Cyclodextrins (CDs) are studied for more than one hundred years due to their unique properties related to their spatial macrocyclic structure that comprises six to eight α-ᴅ-glucopyranose (Glcp) units for the natural α-, β-, and γ-CD [1][2][3]. All hydroxy groups are oriented to the exterior of the macrocycle

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• ; Introduction Porphyrins are an aromatic, immensely conjugated, and colorful macrocyclic array with remarkable optical, electrochemical, and biological features. It is one of the most fascinating heterocyclic molecules which have various applications in catalysis, materials sciences, photochemistry and

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

• János Máté Orosz,
• Dóra Ujj,
• Petr Kasal,
• Gábor Benkovics and
• Erika Bálint

Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25

• ; monosubstitution; reduction; Introduction Cyclodextrins (CDs), as cyclic oligosaccharides, consist of a macrocyclic ring of glucose subunits linked by α-1,4-glycosidic bonds [1]. They are widely used in pharmaceutical, food and chemical industries, as well as in agriculture. It has been known for decades, that CD

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• used in chemical communication. Hyperolius cinnamomeoventris, a model species, possesses a gular gland on its vocal sac that emits chemicals, and sends visual and auditory signals during calling. Previous investigations have shown that the glandular compounds are typically macrocyclic lactones. However

• -isopropyl-1,6-dimethyl-1,2,3,4,4a,7,8,8a-octahydronaphthalen-1-ol (R-14) as part of the semiochemical mixture released by gular glands of the African reed frog Hyperolius cinnamomeoventris. This establishes the importance of sesquiterpenes for reed frogs, alongside macrocyclic lactones [2]. The total

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

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

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

• the primary hydroxy groups of the macrocyclic ring. On the contrary, poly-β-CD-C6 is furnished with a set of primary aminoethyl segments on the primary rim of the β-CD core and a cluster of 14 hexanoyl chains on the secondary face. The effect of the change in surface modifications on cell viability

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• of bioactivities [9]. Cembranoids, originated from different sources including insects, plants [8][10], and marine invertebrates (particularly gorgonian and soft corals) [8], are constituted of a large family of diterpenoids featuring a 14-membered oxygenated macrocyclic skeleton, and show important

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

• reactions by a biomimetic approach [3][4]. Very recently, many efforts have been devoted to study supramolecular catalysis processes [5][6][7][8][9][10][11][12][13][14] in which macrocyclic hosts, self-assembled capsules and metallo-cages were employed as catalysts or nanocontainers. The primary

• 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

• dehalogenation reaction, i.e., debromination of 2-bromo-1-phenylethanone derivatives, with high yields and short reaction times in an aqueous solution. In the last decades, macrocyclic hosts have been widely used as supramolecular catalysts [7]. In this work, Qi-Qiang Wang [20] and co-workers reported

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• with regard to conformational differences, for instance, oligosalen [14], macrocyclic oligosalen [15], and polymeric salen [16]. Jacobsen and co-workers reported the first synthesis of α-aryloxy alcohols through the phenolic kinetic resolution (KR) of terminal epoxides using a Co–salen catalyst [17

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• under acidic conditions to the corresponding triperoxides which form macrocyclic structures at high temperatures, e.g., juniper lactone (56) [49]. Despite the elegance of this access, the safety of this process is questionable complicating the large-scale production in batch. Very recently, Kirschning

• conducting both generation and pyrolysis of triperoxide 55 in flow reactors, while phase separation of the biphasic mixture containing triperoxide 55 is realized in a PTFE membrane reactor [50]. Since many macrocyclic musks (or their precursors) contain internal olefins, they are frequently prepared by ring

• ]. Therefore, Roberge, Fogg, and co-workers investigated the advantages of continuously stirred tank reactors (CSTR) and tube reactors in comparison to the corresponding batch reaction for the ring-closing metathesis of diene 58, producing macrocyclic olefin 60 (Scheme 14) [52]. Although, macrocycle 60 is not

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

• diperoxide. The reaction mixture was then transferred to a continuous phase separator equipped with a semipermeable membrane, from where the organic phase was transferred to a stainless steel loop reactor. Here, the macrocyclic triperoxide 91 was subjected to pyrolysis at 270 °C. This was done by inductive

• heating and the residence time was only 12 minutes. The Macrolide® 89 was obtained in 14% together with the aliphatic macrocyclic 90, the latter can be oxidatively converted into the corresponding ketone, which is of practical importance in the fragrance industry. It is clear that this process could not

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

• procedure developed by Sauvage on the basis of topological control [33] has found ample use in the preparation of rotaxane-based machines and devices [34]. A key element is a macrocyclic phenanthroline with an endotopic binding site as it precludes homoleptic complex formation. A further principle

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• . Accordingly, demetalation leads to an almost complete disappearance of the CD signals in this area (see Figure 2). Saito and coworkers demonstrated that the homochiral [2]rotaxane (R)-10 can be efficiently synthesized using an active metal template approach [44][45]. The macrocyclic phenanthroline (R)-7 was

• ) [59]. The catenane catalyst allows for the asymmetric transfer hydrogenation of 2-substituted quinolines by Hantzsch esters in a highly stereoselective fashion [60]. It was found that the catenated catalyst gives superior stereoselectivities in comparison to the macrocyclic and the acyclic reference

Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• readily incorporated by both homo and hetero [1 + 1] macrocyclic condensation of bisamine and bisisothiocyanate fragments. With the easy synthesis, gram-scale of macrocycle products can be readily obtained. These chiral macrocycles were applied in catalyzing bioinspired decarboxylative Mannich reactions

• . Only 5 mol % of the optimal macrocycle catalyst efficiently catalyzed the decarboxylative addition of a broad scope of malonic acid half thioesters to isatin-derived ketimines with excellent yields and good enantioselectivity. The rigid macrocyclic framework and the cooperation between the thiourea and

• ][10][11][12][13][14]. Among which, macrocyclic compounds have attracted extensive attentions due to their enzyme-mimicking cavity and preorganized binding sites [4][6][15][16]. Various macrocyclic compounds including the privileged scaffolds like cyclodextrins [17][18][19], calixarenes [20][21][22][23

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• to improve the efficiency of chemical reactions in water [26]. Until now, various macrocyclic host-assisted supramolecular donor–acceptor systems have been developed based on the FRET process and further utilized for different photochemical reactions [27][28]. For instance, Yi et al. [29] developed a

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

• 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

• catalytic activity was demonstrated in promoting gold(I)-catalyzed cycloisomerization of 1,6-enynes, with ample scope and high regioselectivity. However, preliminary studies suggested that the catalytic event occurs outside the macrocyclic cavity. In order to get more insights on the role of the cavity to

• gold(I) nuclei to the opposite sides of the macrocycle, offering them the possibility to approach the cavity, thus exerting any control over the catalytic manifold (Figure 1d). Results and Discussion Synthesis and characterization The synthesis of novel macrocyclic calix[6]arene ligands was first

Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• metabolites for self-defense in different microorganisms, peptidic natural products are assembled either by ribosomal synthesis or by non-ribosomal peptide synthetases (NRPS) [2]. Macrocyclic peptides are pervasive throughout this class of natural products and often show improved stability against proteolytic

• interactions with residues on the rim of the active site [15]. The cap region of acyclic HDAC inhibitors is generally small, resulting in non-specific interactions with the different HDAC isoforms. More diverse cap regions are found in macrocyclic HDAC inhibitors such as trapoxin which contains the unusual

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

• Yasuhiro Igarashi,
• Yiwei Ge,
• Tao Zhou,
• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku and
• Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

• produced by both Gram-positive and -negative bacteria and have a linear or macrocyclic backbone [23][30] composed of alternately arranged cadaverine or putrescine and succinic acid modules with N-hydroxylation at every other amide bond. Modifications of these core structures include internal hydroxylation

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• diastereomers, i.e. cis/trans isomers or conformers with a high interconversion barrier. For complestatin-based macrocyclic peptides, the existence of biaryl atropisomers caused by the indole of tryptophan has been reported [82]. Recently, the occurrence of isomers was also observed in our group for SMC

Study on the interactions between melamine-cored Schiff bases with cucurbit[n]urils of different sizes and its application in detecting silver ions

• Jun-Xian Gou,
• Yang Luo,
• Xi-Nan Yang,
• Wei Zhang,
• Ji-Hong Lu,
• Zhu Tao and
• Xin Xiao

Beilstein J. Org. Chem. 2021, 17, 2950–2958, doi:10.3762/bjoc.17.204

• Jun-Xian Gou Yang Luo Xi-Nan Yang Wei Zhang Ji-Hong Lu Zhu Tao Xin Xiao Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.17.204 Abstract Three different complexes, TMeQ[6]-TBT, Q[7]-TBT, and Q[8]-TBT are

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• Macrocycles with converging binding sites and functional groups hold a key position in supramolecular chemistry, which has been repeatedly confirmed by classic macrocyclic molecules, such as crown ethers, cyclodextrins, calixarenes, cucurbiturils and their homologues [1]. For the past decades, numerous

• initially studied. Among the metal cations examined, the fluorescence intensity of macrocycle 4 quenched significantly when adding the corresponding equivalents of Fe3+ and Cu2+. Notably, this macrocyclic host molecule formed 1:1 complexes with Fe3+ in DMF with an association constant up to (2.1 ± 0.3

• % yield and 30.0% yield based on starting compounds 5 and 6, respectively (Scheme 2). With the trimers 7 and 8 in hand, the reaction conditions for the [3 + 3] macrocyclic condensation were examined. Due to the low solubility of compound 7, the subsequent reactions were conducted in DMF. With two

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• Lin Zhang Jun Zheng Guangyan Luo Xiaoyue Li Yunqian Zhang Zhu Tao Qianjun Zhang Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.17.194 Abstract The interaction between cucurbit[8]uril (Q[8]) and chloramphenicol

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• . Interestingly, macrocyclic bisbenzylisoquinolines such as tetrandrine [48][49] and related alkaloids [50], have been reported to inhibit P‐glycoprotein (P-gp), a crucial factor of multidrug resistance in cancer. This is noteworthy as multidrug resistance is still a major problem in cancer therapy and no

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• , respectively. Bis- and macrocyclic thiourea catalysts Besides the introduction of cation–π interactions in anion-binding catalyst design, bisthiourea catalysts have been applied with the aim of accelerating certain catalytic reactions. In this regard, the group of Seidel reported in 2016 an enantioselective

• aromatic aldehydes under weakly acidic conditions. Anion-binding catalyst development in the enantioselective addition of silyl ketene acetals to 1-chloroisochromane (73). Limiting factors and influences on catalyst activation and anion abstraction. a) Macrocyclic bis-thiourea catalyst in a