The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• use of triflic acid (TfOH) resulted also in the cleavage of the alkyl group derived from the isocyanide, with formation of 47 (Scheme 18). Kanizsai et al. [51] have reported the synthesis of 4,5-disubstituted 2-amino-1H-imidazoles and their further modification through the GBB-3CR. The 2

• precursors which can be involved in further modifications. In addition, the GBB-like reactions can also be used to deliver other heterocyclic motifs. 3.1 One-pot synthesis As an efficient approach in organic synthesis, one-pot synthesis has been exploited in the post-modification of GBB products. This

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• is recognized by post-translational enzymes and a core peptide where these enzymes produce the formation of Dha-Cys or Dhb-Cys residues. The post-translational modification enzymes involved span different functional domains (a cyclase and a dehydratase), and their activity is tightly controlled at

• -translational modification enzymes The selected supercluster is predicted to be formed by two adjacent, biosynthetically complete transcriptional units, each with specific promoter and terminator sites (Figure 2) containing two LanM enzymes (CloM1 and CloM2), the precursor peptides CloA1 and CloA2, as well as

• predictions suggesting that this should be a functional system. This lack of modification could be due to the amino acid sequence of the precursor, which differs from those described in the literature, or to mutations in the CloM1 enzyme. These mutations may require additional co-factors or specific

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• well as their analogs, is outlined with an emphasis on comparing these chemo-enzymatic syntheses with the corresponding natural biosynthetic pathways. Keywords: chemo-enzymatic synthesis; late-stage modification; reactive biosynthetic intermediate; regio- and stereoselective (macro)cyclization; total

• pentacyclic scaffolds. The designed and chemically synthesized substrate analog 96 was tolerated by the key NRPS module SfmC despite the structural modification (Scheme 10A). In vitro enzymatic conversion of 96 with tyrosine derivative 86 [103] followed by the addition of KCN concisely furnished the

• relies heavily on enzyme selection and substrate design. The first strategy, "site- and stereoselective late-stage modification", was highlighted by demonstrating the systematic total synthesis of cotylenol (1) and its related natural products, brassicicenes (Scheme 2 and Scheme 3). Natural and

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• encoded in the same BGC as the precursor peptide install post-translational modifications in the core peptide. Finally, a protease releases the modified core peptide, creating the mature natural product [2]. The transfer of a methyl group is a common post-translational modification in RiPP biosynthesis

• ]. Further O-MTs can be classified based on a common acceptor group of modification, namely C-terminal carboxy-MTs and peptide/protein ʟ-aspartyl O-MTs (PAMTs). C-terminal carboxymethyltransferases Carboxy-MTs catalyse the formation of a methyl ester by methylating the oxygen atom within the hydroxy group of

• aspartimide intermediates (Figure 6). The activity of most PAMTs depends on a cyclised precursor peptide. Modification of the aspartate/isoaspartate residue was found only in a hairpin-like or the macrocyclic region [71][78]. The underlying purpose of this structural requirement of PAMTs has not yet been

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• fundamentally signaling molecules and enzymatic modification of AQs by Microbulbifer could represent a mechanism of ecological cross-talk among marine microbiomes. Enzymatic halogenation of other signaling molecules, such as that of acyl homoserine lactones, has been postulated to modulate bacterial

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• membranes for these electrochemical devices [14][20]. However, many technological limitations remain due to the high dependence of the membrane’s performance on the presence of water or other electrolyte content. To overcome these limitations, the modification of the membrane can be done by the

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• photoisomerization from O-DA7 to C-DA7 and from O-DA6 to C-DA6 in aqueous solutions. No thermal back reaction was observed for DA7 (Figure S3, Supporting Information File 1) and DA6 (Figure S4, Supporting Information File 1), similarly to DA11 and DA10. The results indicated that even a subtle modification of the

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• -translational modifications by specific tailoring enzymes [5][6]. This precursor peptide substrate can be subdivided into multiple segments including 1) an N-terminal leader or recognition sequence used for binding by the tailoring enzymes and 2) a core peptide that is targeted for modification by the

• (Figure 7 and Supporting Information File 1, Figures S13–S15). While unusual, this motif could be biosynthetically related to the alpha-hydroxy modification seen in vignatic acid [35]. These potential compounds are bicyclic which resemble the bicyclic motif found in moroidin from the closely related C

Bioinformatic prediction of the stereoselectivity of modular polyketide synthase: an update of the sequence motifs in ketoreductase domain

• Changjun Xiang,
• Shunyu Yao,
• Ruoyu Wang and
• Lihan Zhang

Beilstein J. Org. Chem. 2024, 20, 1476–1485, doi:10.3762/bjoc.20.131

• formed during post-PKS modification [22][34]. To gain a better understanding of the stereoselectivity of KRs in γ- and δ-modules, we focused on KRs associated with an inactive DH domain (DH0) that still produce a β-hydroxy intermediate. These KRs are phylogenetically mixed together with those in γ- and δ

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• reaction media led to higher yields. More precisely, dimethoxyethane (DME) gave a superior result to THF, affording 4aa in 82% yield (Table 1, entries 10–16). Subsequently, modification of the reaction temperature or concentration turned out to be unsatisfactory (Table 1, entries 17–19). We also added 4 Å

Synthesis of substituted triazole–pyrazole hybrids using triazenylpyrazole precursors

• Simone Gräßle,
• Laura Holzhauer,
• Nicolai Wippert,
• Olaf Fuhr,
• Martin Nieger,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2024, 20, 1396–1404, doi:10.3762/bjoc.20.121

• sources and thus as building blocks for synthesizing pyrazolyltriazoles by CuAAC reactions. To find a feasible approach to pyrazolyltriazoles of type 1 with a highly substituted scaffold, we decided to explore the benefits of a modification of the triazene-protected pyrazole core. In the next step, a

Synthesis and physical properties of tunable aryl alkyl ionic liquids based on 1-aryl-4,5-dimethylimidazolium cations

• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2024, 20, 1278–1285, doi:10.3762/bjoc.20.110

• introduced a new class of ionic liquids based on the 1-aryl-3-alkylimidazolium cation in 2009, the tunable aryl alkyl ionic liquids (TAAILs) [29]. This class of ionic liquids allows the modification of physical and chemical properties by variation of the functional groups present at the aryl ring of the

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• [8][9]. In the last few years we have been active in isatin modification using new synthetic approaches, anticipating the creation of new libraries of small-molecule hybrids with potential as cholinesterase inhibitors [10][11][12][13], important to treat neurodegenerative diseases, and anticancer

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• dissolved in aqueous hydrogen peroxide and was gradually added to the reaction mixture, containing the remaining chemicals. The addition time of this aqueous reagent was also shortened to 15 minutes, to counteract the slow decomposition of H2O2 caused by NaBr. This modification ultimately resulted in nearly

• , when used with light irradiation as halogen initiator, is capable of selectively convert xylene isomers and mesitylene into their corresponding benzyl bromides, regardless the presence of halogen atoms on the core. Moreover, under dark conditions, a modification of the same method allows the

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• modification, the storage energy of 158.57 kJ/mol, energy storage density of 1.48 MJ/kg, TBR barrier of 136.36 kJ/mol, and the absorption onset of 305.00 nm is achieved in acetonitrile. These values are substantially higher when compared with the storage energy (96.06 kJ/mol), energy storage density (1.04 MJ

Novel analogues of a nonnucleoside SARS-CoV-2 RdRp inhibitor as potential antivirotics

• Luca Julianna Tóth,
• Kateřina Krejčová,
• Milan Dejmek,
• Eva Žilecká,
• Blanka Klepetářová,
• Lenka Poštová Slavětínská,
• Evžen Bouřa and
• Radim Nencka

Beilstein J. Org. Chem. 2024, 20, 1029–1036, doi:10.3762/bjoc.20.91

• . We focused on the modification of the central heterocyclic core and on the simplification and truncation of the relatively large molecule 1 (Figure 1). In this work, replacing the sulfur atom with a (bio)isosteric oxygen atom yielded two novel structural analogues, whilst our effort towards more

• and thiadiazolopyridone derivatives because molecules based on these cores have already shown promising antimicrobial activities [25][26]. Results and Discussion Synthesis of HeE1-2Tyr (1) structural analogues Modification of the core: synthesis of pyridobenzoxazole derivatives The synthesis of the

• most successful modification. The potential of the truncated derivatives was further illustrated by the thiazolopyridone and thiadiazolopyridone compounds 4a,b, which showed inhibition with IC50 = 88.1 μM and 128.7 μM, respectively. Even though the measured inhibitory concentration was higher than that

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• selectivity with the noncanonical prenyl substrates. To enable the biotechnological synthesis of irregular terpenes, the product selectivity of 2-methylenebornane synthase from Pseudomonas fluorescenes was altered using a semi-rational engineering approach [56]. In contrast to GPP methylation, modification of

• selective sesqui-TSs failed to transform 104–112. After further modification with cytochrome P450 CYP720B1 in the yeast host, 28 noncanonical terpenoids were generated, 10 of them are shown in Figure 8c (113–122) [58]. Notably, the widespread biosynthesis of C16 terpenoids was reported in a recent study in

Innovative synthesis of drug-like molecules using tetrazole as core building blocks

• Jingyao Li,
• Ajay L. Chandgude,
• Qiang Zheng and
• Alexander Dömling

Beilstein J. Org. Chem. 2024, 20, 950–958, doi:10.3762/bjoc.20.85

• moiety is introduced in a late-stage-modification approach, mostly from nitriles or isocyanides (Figure 1b) [13]. On the other hand, accessing diverse tetrazole scaffolds from MCRs, typically involves first de novo construction of the tetrazole scaffold and subsequent post-modifications (Figure 1c) [14

• synthetic utility of this tetrazole scaffold continues, particularly in other MCRs and post-modification processes, we anticipate more applications in the near future. Investigation of these drug-like molecules for the targets PD-1/PDL-1, caspase-1, and IL-17A are currently in progress in our laboratory

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• commercial drug baclofen as hydrochloride. Keywords: desymmetrization; enantioselective Heck–Matsuda reaction; lactam synthesis; N,N-ligands; palladium; Introduction Desymmetrization reactions consist in the modification of a molecule with the loss of one or more symmetry elements, such as those which

Monitoring carbohydrate 3D structure quality with the Privateer database

• Jordan S. Dialpuri,
• Haroldas Bagdonas,
• Lucy C. Schofield,
• Phuong Thao Pham,
• Lou Holland and
• Jon Agirre

Beilstein J. Org. Chem. 2024, 20, 931–939, doi:10.3762/bjoc.20.83

• filtering by linkage type is also possible, allowing niche glycosylation targets to be obtained. For example, filtering for C-glycans with a ‘BMA-1,1-TRP’ (the correct pair would be ‘MAN-1,1-TRP’, as the linkage in the modification is an alpha linkage) returns nine instances of incorrect sugar conformations

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• targets, making uracil very interesting for medical applications. The first modification of uracil was already synthesized in 1906 [6]. However, the medical potential of uracil was not discovered until 40 years later. One of the first antibacterial studies was carried out in 1945. The first

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• well as the impact they have on the physiochemical and biological properties of pharmaceuticals and agrochemicals. Keywords: bioisosteres; drug discovery; meta-benzene; ortho-benzene; Introduction The logical and iterative modification of the structure of a drug candidate is a critical part of the

• -workers also reported the modification of these 1,2-BCHs to increase the number of derivatives accessible using this approach (Scheme 3B) [38]. Transformation of the naphthyl ketone moiety of BCH (±)-25d by Baeyer–Villiger oxidation followed by hydrolysis gave carboxylic acid (±)-26. Through Curtius

• -substituted endo-1,5-BCHs (±)-57a–e. Substrate modification was also possible, with oxidative transformation of a bridgehead furan leading to 1,5-BCH acid (±)-60 and pyridine reduction to secondary amine (±)-61 (Scheme 5B) [42]. Furthermore, 1,5-BCH (±)-64 was synthesised as a bioisostere of the fungicide

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• portion of NNG would be expected to exist as the inhibitory nitronate form at physiological pH, suggesting another potential role for nitramine groups as potent warheads in antibiotics. This antibiotic activity may also require further modification of NNG or its incorporation into a larger natural product

• pET-28a(+)-TEV by GenScript. For protein expression, plasmids were electroporated into E. coli BL21(DE3) cells and protein was expressed and purified by immobilized metal affinity chromatography (IMAC) as previously described for Vs NnlA [21]. The only modification was that plasmids using pET-28a

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus

• Dongxu Zhang,
• Wenyu Du,
• Xingming Pan,
• Xiaoxu Lin,
• Fang-Ru Li,
• Qingling Wang,
• Qian Yang,
• Hui-Min Xu and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73

• derivatives 7–9. This study marks the first discovery of natural DMTs from bacteria and unveils the role of CavA in a novel late-stage modification pathway, expanding DMT biosynthesis beyond fungi and plants. Results and Discussion Discovery of three DMTs in S. clavuligerus S. clavuligerus is notably

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• oxidation, whereas in Nicewicz's report, the alkene is oxidized. This modification allows for a significantly larger reaction scope (Scheme 29). Terminal alkenes and several functional groups such as ethers (163), esters (165), ketones (166), nitriles (167), and enones (170) are tolerated. The