Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• options for treating vinca alkaloid- and taxol-resistant cancers [79]. Therefore, the pharmaceutical investigation of these natural products started for the first time when they were isolated in the early 1990s and has lasted until the present. A synthetic analog, cryptophycin 52, completed phase I

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• terpene alkaloid; natural products; Penicillium; structure elucidation; Introduction Penicillium, a genus within the Ascomycota phylum, is a type of critical saprophytic fungus with over 400 strains identified in diverse environments such as mountains, oceans, and the human gut [1]. After the first

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• number of alkaloid natural products can be accessed from commercially available tropone in as little as five steps: 1) formation of tricarbonyl(tropone)iron, 2) aza-Michael addition, 3) amine protection, 4) photodemetallation, and 5) intramolecular Heck reaction (two steps – aza-Michael addition and

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• thiiranium ion by the tosylamide and deprotonation led to the final product 99 or 100 (Scheme 41). Through the coupling reaction of N-(aryl/alkylthio)succinimides 1 with 5H-oxazol-4-ones 101 in the presence of an organocatalyst named cinchona alkaloid-derived squaramide F, a series of α-sulfenylated products

• acid catalyst I, leading to the formation of an electrophilic sulfenium source (Scheme 49). The use of dimeric cinchona alkaloid J as another organocatalyst for α-sulfenylation of deconjugated butyrolactam substrates 117 with N-(arylsulfanyl)succinimides 1 demonstrated in Mukherjee′s work (Scheme 50

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

• . Cinchona alkaloid O2 was the efficient catalyst for this asymmetric C–C bond formation delivering the products with moderate to good enantioselectivities. One example was documented involving β-naphthol as nucleophile and another example included electron-rich phenol (Scheme 31) [61]. Lin, Duan and co

• benzothiazolimines. Thiourea-catalyzed reaction between β-naphthol and isatin-derived ketamine. Quinine-derived molecule as catalyst. Cinchona alkaloid as catalyst. aza-Friedel–Crafts reaction by phase transfer catalyst. Disulfonamide-catalyzed reaction. Heterogenous thiourea-catalyzed aza-Friedel–Crafts reaction

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

• demonstrated the synthesis of polygonatine, an alkaloid natural product, using this protocol. (2) Reactions under solvent-free conditions In recent years, interest in organic reactions that do not use toxic organic solvents has increased due to environmental considerations. Ramesh et al. [71] in 2012 reported

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

• position via a sequential electron transfer–proton transfer (ET/PT) [52][53][54][55][56][57][58][59]. With our ongoing interest of establishing new methods for the asymmetric synthesis of nonproteinogenic tryptophan derivatives as well as their associated indole alkaloid natural products [60][61][62][63

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

• ], the cyclic guanidine alkaloid massinidine [17], and the siderophore massiliachelin [18]. An antiSMASH analysis [19] of the genome of Massilia sp. NR 4-1 revealed the presence of additional biosynthetic gene clusters, including another putative metallophore gene cluster (ACZ75_RS05545–ACZ75_RS06020

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

• occurrence among natural products [1] and is a key structural component of several pharmaceuticals, agrochemicals, dyestuffs, and materials. Particularly, the well-known antimalarial alkaloid quinine isolated from Cinchona bark comprises a quinoline core (Figure 1a) [2]. Moreover, numerous quinoline

Synthesis, α-mannosidase inhibition studies and molecular modeling of 1,4-imino-ᴅ-lyxitols and their C-5-altered N-arylalkyl derivatives

• Martin Kalník,
• Sergej Šesták,
• Juraj Kóňa,
• Maroš Bella and
• Monika Poláková

Beilstein J. Org. Chem. 2023, 19, 282–293, doi:10.3762/bjoc.19.24

• modifications are possible and many of these compounds inhibit glycoprocessing enzymes [11][12][13][14]. One of the best known iminosugars is the natural alkaloid (−)-swainsonine, which is a nanomolar inhibitor of human Golgi α-mannosidase II (GMII, GH38 family, E.C.3.2.1.114). Although such inhibition has been

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

• . This protonation effectively prevents any possible side reactions of the dearomatized products with electrophiles. A remarkably wide substrate scope was observed for this dearomative indole cyclopentannulation reaction, as demonstrated by the smooth ring expansion of the natural alkaloid drug yohimbine

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

• –2022. Review Radical-based divergent synthesis Commonly, the most successful divergent plans apply where the natural molecular complexity is rich. Not surprisingly, most of the divergent total syntheses carried out thus far are performed on terpenoid and alkaloid targets, utilizing common synthetic

• ]: Reticuline-type alkaloid oxidative coupling is a well-established biosynthetic pathway that produces important pharmaceutical structures [93], such as (+)-corytuberine, (−)-codeine, (−)-morphine, (+)-sebiferine (181), etc., depending on the regioselectivity of the coupling (Scheme 15) [94]. During this

Navigating and expanding the roadmap of natural product genome mining tools

• Friederike Biermann,
• Sebastian L. Wenski and
• Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

• ])) [28]. In contrast, discrete multi-enzymatic assemblies utilize distinct, monofunctional enzymes. Examples are terpene (e.g., cyclooctatin (8) [29]), ribosomally synthesized and post-translationally modified peptide (RiPP), or NRPS-independent alkaloid pathways. In the case of terpene biosynthesis

• its decoration (e.g., in (I) ribosomally synthesized and post-translationally modified peptide, (II) terpene, or (III) alkaloid biosynthesis). Universal (A, B, F) NP class and NP family-specific (C, D, F) signature sequences in NP BGCs and selected examples of each scenario. Genome mining tools

• pathways), (D) as well as signature motifs (e.g., RiPP biosynthetic pathways that utilize tailoring enzymes containing RREs). (E) BGCs without signature sequences (e.g., NRPS-independent alkaloid biosynthesis) or (F) genomically dispersed (i.e., not clustered) genes (here also referred to as biosynthetic

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• structural component of the pyrrolizidine alkaloid monocrotaline. Keywords: β-hydroxylactone; intramolecular reductive aldol cyclization; necic acid lactone; rhodium catalyst; Introduction Carbon–carbon bond-forming reactions are among the most important reactions in the synthetic chemistry toolbox and the

• antimicrobial activity. Moreover, antiviral activity was also confirmed for aggregatin B [52] containing a 7-membered lactone ring, in which the β-position hydroxy group was dehydrated (Figure 1). Monocrotaline is a kind of pyrrolizidine alkaloid and was isolated from seeds of Crotalaria spectabilis in 1935 [53

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• acids. Keywords: alkaloid; amino acid; aza-Prins reaction; cascade reaction; natural product; Introduction Marine sponges produce a large number of structurally diverse natural products, including many that exhibit biological activity [1][2][3]. In 2019, Tsukamoto and co-workers isolated the

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

• hydrogenated base and fully aromatized base, in which natural fully aromatic alkaloids can be further classified into three subclasses: O4-base, O5-base, and O6-base [3]. Among these alkaloids macarpine is the most oxidized tetracyclic alkaloid with many bioactivities, including anesthesia, anticancer, anti

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• UHPLC–MS analysis of the extract from this sponge indicated the presence of a new alkaloid. Large-scale extraction and mass-directed isolation studies on the CH2Cl2/MeOH I. basta extract resulted in the purification of a new bromotyrosine-derived alkaloid, 5-debromopurealidin H (1), along with the known

• (6), hexadellin A (9) and bastadin 4 (5) showed inhibition towards larval motility after 72 h of exposure with IC50 values of 1.6 µM, 10.0 µM and 33.3 µM, respectively. Keywords: alkaloid; anthelmintic; biodiscovery; bromotyrosine; 5-debromopurealidin H; Ianthella; NatureBank; sponge; Introduction

• identify samples containing abundant or potentially new natural products. A sample from the Australian marine sponge Ianthella basta was chosen for large-scale isolation work after analysis of the UHPLC–MS data and the MarinLit database [1] suggested the presence of a new alkaloid. Herein, we describe the

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• Palau’amine (45), a dimeric pyrrole-imidazole-bisguanidine alkaloid, was first isolated from the marine sponge Stylotella aurantium in 1993 [16][17]. It received considerable attention from the synthetic community because of its broad range of biological activities and complex structure. In an early endeavour

• pentacyclic, antiproliferative quinoline alkaloid camptothecin (65), Peters et al. used an α-ketoester moiety in an auxiliary controlled approach towards the only stereogenic center present in the natural product (Scheme 10) [25]. First, the ketoacid 60 was esterified with 8-phenylmenthol (61) to yield the α

• also be used in photochemical reactions, as shown by Gramain et al. in the synthesis of the pyrrolizidine alkaloid (rac)-isoretronecanol (69, Scheme 11) [26]. A Claisen condensation of the lithium enolate of N-acetylpyrrolidine (66) with diethyl oxalate gave the ketoester 67. Irradiation of compound 67

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• Nisha Devi Virender Singh Department of Chemistry, DAV University, Jalandhar-Pathankot National Highway (NH 44), Jalandhar, 144012, Punjab, India Department of Chemistry, Central University of Punjab, Bathinda, India 10.3762/bjoc.18.92 Abstract β-Carboline is a privileged class of the alkaloid

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

• Martin Vrbický,
• Karel Macek,
• Jaroslav Pochobradský,
• Jan Svoboda,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

• -one derivative. Here, we extended the series of catalysts to include copper complexes with another six 2-(pyridin-2-yl)imidazolidin-4-ones Ia,b–IIIa,b [20][21][22], four bisoxazolines IV–VII [23][24], and as chiral diamine, the alkaloid (+)-sparteine VIII [25] (Figure 2). All Henry reactions were

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

• from cinchonine PTC 44 as catalyst. Despite of good yields, the method did not demonstrate good enantioselectivity results [104]. Berkessel and co-workers, in turn, described the use of asymmetric Weitz–Scheffer-type epoxidation of menadione (10), mediated by cinchona alkaloid PTC 45, showing high

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• intermediates have found use in the total synthesis of (+)-norchelidonine (an isoquinoline alkaloid) [55], sertraline (an antidepressant) [56], and arnottin I (an anti-inflammatory) [57]. Although OBD 1 has been shown to undergo many different modes of reactivity in both a stereo- and enantioselective manner

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• results, it was found that the yield of product did not increase significantly with the cinchona alkaloid-derived squaramide catalysts (Table 1, entries 2 and 3). Consequently, we decided to explore the effects of different types of catalysts on the reaction. Through experiments, it can be found that

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• Bratislava, Radlinského 9, 81237 Bratislava, Slovak Republic 10.3762/bjoc.17.188 Abstract A new highly diastereoselective synthesis of the polyhydroxylated pyrrolidine alkaloid (±)-codonopsinol B and its N-nor-methyl analogue, starting from achiral materials, is presented. The strategy relies on the trans

• evaluated using several cell line models. Keywords: alkaloids; antiproliferative effect; codonopsinol B; diastereoselectivity; pyrrolidines; Introduction Codonopsinol B (1) is a polyhydroxylated pyrrolidine alkaloid isolated from the roots of the plant Codonopsis pilosula (Figure 1) [1]. This compound was

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

• ][4][5]. In continuation of our recent work on the chemistry and pharmacology of benzylisoquinolines and related compounds [6][7][8][9][10][11][12][13][14] we investigated truncated analogues of the bisbenzylisoquinoline alkaloid tetrandrine as blockers of the calcium channel two-pore channel 2 (TPC2

• by lithium alanate reduction [18][19]. In a novel total synthesis of the racemic alkaloid N-methylcoclaurine (1) performed in this course we also used the ethoxycarbonyl group successfully for protection of two phenolic groups at two different rings during the N-acyl-Pictet–Spengler reaction [15

• comparison to tetrandrine and cepharanthine, we performed Ca2+ measurements in multiwell plates. Therefore, heterologously TPC2-expressing HEK293 cells were loaded with calcium indicator fluo-4/AM and Ca2+ entry was measured for 5 min after injection of various alkaloid concentrations (0.1–100 µM). None of