New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

• Elenilson F. da Silva,
• Krist Helen Antunes Fernandes,
• Denise Diedrich,
• Jessica Gotardi,
• Marcia Silvana Freire Franco,
• Carlos Henrique Tomich de Paula da Silva,
• Ana Paula Duarte de Souza and
• Simone Cristina Baggio Gnoatto

Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161

• representation) inside the IMPDH active site from Mycobacterium tuberculosis (cartoon representation – PDB code 4ZQP), with selected residues and interactions here also represented. Synthesis of 1-azido-3-nitrobenzene (c). Synthesis of the triazole-substituted triterpene derivatives 7 and 8. Antiviral activity

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

• characteristic of supramolecular catalysis is that the general modes of activation based on intermolecular interactions can operate on substrates in a selective way, and in confined environment, like the active site of natural enzymes [5][6][7][8][9][10][11][12][13][14]. As a result, molecular recognition of the

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• enzymatic coupling to complete the sugar nucleotide [7][8]. With this capability in place, we wished to explore the synthesis of further tools, targeting the active site cysteine residue (Figure 1c). We envisaged that access to C6–amino or C6–sulfhydryl species of type 8 would offer prospect to establish

• active site thiohemiaminal (amine to imine oxidation) or disulfide formation, respectively. Additionally, C6–Cl derivative 9 could probe cysteine alkylation. Reported herein is our exploration of this synthesis and the evaluation of GDP 6-chloro-6-deoxy-ᴅ-mannose 18 against GMD. Results and Discussion

• modifying C6 [4]. Substrate 18 was known to form a disulfide in solution [10], presumably resulting in the glycosyl-1-phosphate being unable to access the enzyme active site; unfortunately, the addition of higher concentrations of reducing agent (DTT) and solid-supported PPh3 to access the reduced form for

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• reactions (Figure S1, Supporting Information File 1). Due to the high reaction selectivity that the enzyme active site offers, these enzymes provide biocatalytic means for the biaryl linkage formation, and recent enzyme engineering efforts also demonstrated selective and efficient production of unnatural

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

• Shani Zev,
• Marion Ringel,
• Ronja Driller,
• Bernhard Loll,
• Thomas Brück and
• Dan T. Major

Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97

• two byproducts, isoelisabethatrienes A and B. Fascinatingly, a single active site mutation (M75L) diverts the product distribution towards isoelisabethatrienes A and B. In the current work, we study the competing pathways leading to these products using quantum chemical calculations in the gas phase

• , having antibiotic and anti-inflammatory activities, respectively [4][5]. Unexpectedly, a single active site mutation, M75L, significantly shifts the product distribution and IE A becomes the dominant product (44%) in this enzyme variant [6]. As suggested by Rinkel et al., both routes (HP and IE routes

• ) proceed from the same substrate (GGPP) with an initial C1–C10 cyclization. In other TPS enzymes, the initial fold of GGPP in the active site can result in different initial cyclization, for example C1–C6, C1–C7, C1–C10, C1–C11, C1–C14, and C1–C15. The main difference between the two pathways to HP and IE

The stereochemical course of 2-methylisoborneol biosynthesis

• Binbin Gu,
• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82

• solved [32][33]. Notably, the structure of 2MIBS has been obtained in complex with the non-reactive substrate analog 2-fluoro-GPP (2FGPP), showing the substrate surrogate in a stretched conformation in the active site of 2MIBS (Figure 1A). The observed conformation of 2FGPP, if this is also relevant for

• this sample (<1%). A possible explanation is that (S)-2-Me-LPP can bind to the active site of 2MIBS in a non-productive conformation. Its enzyme assisted isomerization to 2-Me-GPP followed by a conformational change may allow for another isomerization to (R)-2-Me-LPP and thus lead to the observed minor

• site water involved in the formation of 1, if (S)-2-Me-LPP occupies the active site of 2MIBS. The formation of 6 and 9 in the incubations of (R)- and (S)-2-Me-LPP with 2MIBS seems to be non-enzymatic in all cases, because the enantiomeric composition of these products is nearly the same for enzymatic

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• reduced to produce PGH2. PGH2 is metabolized by downstream enzymes to yield a series of prostaglandins, which play important roles in inflammatory responses [35][36][37]. Although the active site architectures of COX-1 and COX-2 are not completely identical, the reaction mechanisms and catalytic residues

• activates the catalytic tyrosine residue, while the cyclooxygenase-site catalyzes the formation of di-peroxides. The active site of the peroxidase-site contains a heme cofactor in the solvent-exposed cleft on the opposite side of the membrane binding domain. Although the heme cofactor is located in the

• peroxidase-site and the active site of peroxidase-site and cyclooxygenase-site are separated, the heme cofactor plays a critical role in both of peroxidase reaction and cyclooxygenase reaction. The active site of the cyclooxygenase-site consists of a deep, L-shaped hydrophobic cavity, referred to as the

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

• stabilized within the catalytic cavity. Release from the active site then requires destruction of the stabilizing interactions. For instance, Nature has chosen in the ATP-synthase to use “fueled” nanomechanical motion to release ATP from the active site [23]. Switchable catalysis due to reversible assembly

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• the active site of the enzyme. Once bound, substrate activation is carried out by specific amino acid side chains that adorn the inner surface of the cavity by means of a combination of covalent and/or weak intermolecular interactions leading to the stabilization of intermediate species and transition

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• molecules orienting precisely fixed towards the active site of the enzyme through multiple noncovalent interactions [68][69]. Inspired by the magical ability of the enzyme’s receptor site to act on the substrate with fixed orientation, the Breslow group has done a lot of leading works [25][26] utilizing

• containers, which have drawn much attention in the past years and shown broad prospects in the future. The supramolecular cavity and its constrained microenvironment resemble the active site of natural enzymes, where the guest substrate is encapsulated and positioned with a specific fixed orientation and

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• graphene and the promotional effect of Co-dopants which lay out more Pd active site for the reactants. Mahyari et al. reported a facile, efficient, and environmentally friendly protocol for the coupling of aryl halides and phenylacetylene using a diverse strategy. Third generation polypropyleneimine

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

• Peterson de Andrade,
• Sanaz Ahmadipour and
• Robert A. Field

Beilstein J. Org. Chem. 2022, 18, 208–216, doi:10.3762/bjoc.18.24

• differentiate both enzymes. Moreover, such selectivity might be reasoned based on a possible steric hindrance caused by a bulky hydrophobic loop that sits over the TcTS active site and may prevent the hydrophobic inhibitors from binding. The present study is a step forward in exploiting subtle structural

• the development of potent and selective inhibitors can serve as the basis for new therapeutics [3]. Despite the low primary sequence similarity among human, viral and non-viral sialidases (bacterial and protozoa), they all share a similar catalytic domain with active site residues highly conserved

• [4]. For instance, hydrophobic pockets in the glycerol- and acetamide-binding subsites have been reported for neuraminidases [10][37] as well as for TcTS, which has a more spacious and hydrophobic active site around C9 of sialic acid [16]. Nonetheless, a simple comparison from the crystal structures

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

• ]. Three of these enzyme classes (I, II, and IV) contain Zn2+ within the active site, and therefore these enzymes can be affected by typical Zn2+-binding HDAC inhibitors. In cellular systems, an acetylated lysine of a histone is entering the cavity of the active site and gets coordinated to Zn2

• +. Subsequent attack of water forms a tetrahedral intermediate which results in a cleavage of the acetylated lysine. Most HDAC inhibitors act as substrate mimics and contain a zinc-binding motif. They competitively interact with the HDACs to form stable intermediates and therewith block the active site. Many

• 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

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• incorporated by its nucleophilic attack at a cationic intermediate, leading to terpene alcohols [5][6] or sometimes ethers [7][8]. Substrate ionisation by TPSs is achieved through binding of the diphosphate portion to a trinuclear Mg2+ cluster in the active site that is itself bound to two highly conserved

• synthases seem to be quite random, only the active site is lined with mostly non-polar residues. They contour the active site and force the substrate into a certain conformation which, after substrate ionisation, determines the reaction pathway that is taken by the cationic cascade. Here we present site

• -directed mutagenesis experiments with the sestermobaraene synthase SmTS1 [16] that target the positions usually taken by the described structural anchors and active site contouring residues. Results and Discussion Analysis of active site residues of SmTS1 The recently described sestermobaraene synthase

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• of the self-assembly of cellulose chains at the active site of the enzyme suggested that diffusion of the aggregated molecules and the monomers around the active center dictates the DP that can be obtained by enzymatic polymerization [70][71]. This could be the reason causing enzymatic reactions to

• stop after a certain chain length, as the active site becomes overcrowded. Thus, by modifying the reaction medium, a better control over the DP may be achieved. Longer cellulose chains (DP > 100) were obtained using DMAc/LiCl as reaction solvent and a cellulose surfactant complex, even though in low

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• decatetraenedioic acid connected via an ester bond. There is also a methoxy group, an epoxide and a terpene derived aliphatic chain that contains another epoxide, linked to cyclohexane. These unstable di-epoxides are responsible for the biological activity of fumagillin, which targets the active site of the

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• prochiral diol esters. The enzyme reacts enantiospecifically with the ester to release a chiral product, leaving the acyl group attached to the active site. In a second stage the achiral acyl group undergoes hydrolysis by water. In the desymmetrisation of diols (and diacids, below) kinetic amplification can

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• 3), whilst a high surface area around 150 m2⋅g−1 was proposed to increase the number of exposed sites [214]. Zn@TiNT afforded BHET in 87% yield at 196 °C reaction temperature. TiNT have received significant general interest in heterogeneous catalysis because of the better active-site-accessibility

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• derivatives 85 were obtained. The phosphonate moiety in these analogues represented an important new lead in the development of folylpolyglutamate synthetase inhibitors (Scheme 14) [29]. γ-Phosphonodepsipeptides were also designed and synthesized as potent inhibitors and active site probes of γ-glutamyl

• the macrocyclic phosphonodepsipeptide backbone closely approximated that of the lead inhibitor and showed the low-energy conformation accommodated in the active site of penicillopepsin without significant distortion (Scheme 34) [54]. Synthesis of γ-phosphonodepsipeptides The acyloxyalkyl esters 194

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• relative activities of 1 vs 2 in the AChE vs BACE-1 assays. One possibility is that analog 2 is induced to adopt the “correct” conformation when binding to both targets (i.e., 2f, Figure 2), and this structure fits well within the AChE active site but poorly within the BACE-1 active site, perhaps due to

• unfavourable interactions of the fluorine substituents of 2 with BACE-1 active site residues. A second possibility is that 2 adopts an “incorrect” conformation upon binding to both targets (e.g., 2a, Figure 2), and this novel molecular shape is readily accommodated by AChE [35] but not by BACE-1, perhaps due

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• short time frame. The current method involves a broad substrate scope, excellent functional group tolerance and leaves the active site for further synthetic transformation. The overall strategy allows the generation of new C–N and C–O bonds in one-pot. Experimental General considerations: The melting

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

• Rémi Martinent,
• Javier López-Andarias,
• Dimitri Moreau,
• Yangyang Cheng,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

• react with carboxylate in the active site to produce an ester, and thus covalently attach the transporter to the fusion protein (Figure 6b). The subsequently added reporter 26 passively diffuses into the cells and labels all free HaloTags. The fluorescence signal from the HaloTag reporter 26 is then

Synthesis, docking study and biological evaluation of ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones as potential inhibitors of the mycobacterial galactan synthesis targeting the galactofuranosyltransferase GlfT2

• Marek Baráth,
• Jana Jakubčinová,
• Zuzana Konyariková,
• Stanislav Kozmon,
• Katarína Mikušová and
• Maroš Bella

Beilstein J. Org. Chem. 2020, 16, 1853–1862, doi:10.3762/bjoc.16.152

• synthesized. We performed docking studies of these compounds into the active site of GlfT2 by computational chemistry methods. Although the docking study showed good binding affinities of the prepared compounds towards the GlfT2 active site, their biological evaluation revealed a very poor effect on the

• substrate of mycobacterial galactofuranosyltransferase GlfT2 in the transition state, we evaluated these compounds by computational methods, as well as in an enzyme assay for the possible inhibition of the mycobacterial galactan biosynthesis. Our data show that despite favorable docking scores to the active

• site of GlfT2, none of these compounds serve as efficient inhibitors of the enzymes involved in the mycobacterial galactan biosynthesis. Keywords: GlfT2; molecular modeling; mycobacterium tuberculosis; synthesis; transition state inhibitors; Introduction Tuberculosis (TB) is one of the most prevalent

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• ][31], gas separation and absorption [28][29], enzyme encapsulation [36], and even asymmetric synthesis (albeit with a framework that contained a transition metal ion) [37]. However, for the HOF and CAHOF catalysts to have a similar appeal to other regular active site distribution materials, such as