Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• synthesis pathway involving a diastereoselective hydroboration towards (aryltriazolyl)methyl galactopyranosyl derivatives and determined the viability of this as a scaffold for galectin inhibitors by screening a library of fourteen different products against galectins -1, -3, -4C (C-terminal CRD), -4N (N

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• library of aldehydes (aromatic: 97–99% ee; aliphatic: 84–98% ee) [28]. Thereafter, many different kinds of hydrogen bonding-based organocatalysts have been developed for oxo-DA reactions [29][30][31][32][33][34][35]. One kind of organocatalyst in particular, which is based on an oxazoline template with

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• , Finland Oakland University, Department of Chemistry, 146 Library Drive, Rochester, Michigan, 48309-4479, USA 10.3762/bjoc.15.91 Abstract Single crystal X-ray structures of halogen-bonded assemblies formed between host N-hexylammonium resorcinarene bromide (1) or N-cyclohexylammonium resorcinarene

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

• Angélica de Fátima S. Barreto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

• combination of two isocyanide-based multicomponent reactions (azido-Ugi and Passerini reactions) allowed easy access to a library of macrocyclic depsipeptides in only four steps with variations in the size of the macrocycle as well as in the side chains (Scheme 15). This was the first example in which the

• has been found in the use of dynamic combinatorial chemistry (DCC) [42]. One of the most accessible reversible bonds is the imine bond and has been widely used in DCC. In this context, a freezing process of a dynamic combinatorial library (DCL), which is a system of recognition and thermodynamic

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• combinatorial chemistry (DCC) is one of the most important topics which make us understand the relationship between complex molecules and living systems. With this approach, a library of chemical species called dynamic combinatorial library (DCL) can be designed which are in thermodynamic equilibrium with each

• other. Nitschke and co-workers reported, that mixing of 2-formylpyridine (3.0 equiv), 6-methyl-2-formylpyridine (3.0 equiv), tris(2-aminoethyl)amine (1.0 equiv) and ethanolamine (3.0 equiv) in aqueous solution afforded a dynamic library of imines which subsequently could be self-sorted into two distinct

• differences in the crystal packing in the solid state. The products 32 were obtained via thermodynamic control (Figure 18) from a dynamic combinatorial library [53][88]. In 2010, Otto and co-workers observed unprecedented product selectivity for the formation of disulfide macromolecules based on mechanical

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• %). Then, in order to expand the library of DAGs, other fatty acids containing various degrees of unsaturation and chain length were tested. For instance, esterification of MAG 4a with oleic acid (3b), linoleic acid (3c), and arachidonic acid (3d) underwent smoothly in the ball mill affording DAGs 5b–d in

Stereochemical investigations on the biosynthesis of achiral (Z)-γ-bisabolene in Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 789–794, doi:10.3762/bjoc.15.75

• BbS’s native product 5, for (S)-NPP formation of the acyclic elimination product (E)-β-farnesene (1) was observed, which was identified by EI mass spectral library and GC retention index (I = 1460 (HP-5MS), lit: I = 1459 (HP-5MS) [31]). Incubation with (rac)-NPP resulted in a nearly 1:1 mixture of both

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts

• Rodrigo Abonia,
• Luisa F. Gutiérrez,
• Braulio Insuasty,
• Jairo Quiroga,
• Kenneth K. Laali,
• Chunqing Zhao,
• Gabriela L. Borosky,
• Samantha M. Horwitz and
• Scott D. Bunge

Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60

• Table 1 as a guide, an adaptation of entry 3 was chosen to obtain a library of diversely substituted bisindole triads 8. Since coumarin 7 remained unreacted in this approach the examples described in Figure 1 were performed by employing a 2:1 ratio of precursors 1 and 6, respectively, in the absence of

Back to the future: Why we need enzymology to build a synthetic metabolism of the future

• Tobias J. Erb

Beilstein J. Org. Chem. 2019, 15, 551–557, doi:10.3762/bjoc.15.49

• ]. Third and lastly, there cannot enough enzymes be described. The discovery of new enzymes as well as the characterization of homologs of known enzymes needs to be continued and eventually even intensified. Only these efforts will allow to build an exhaustive library of enzyme parts for level 3, level 4

Selectivity in multiple multicomponent reactions: types and synthetic applications

• Ouldouz Ghashghaei,
• Francesca Seghetti and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2019, 15, 521–534, doi:10.3762/bjoc.15.46

• helped to pave the way of combinatorial chemistry and its applications for the fast generation of pharmacological hits through library deconvolution. The reactivity of the system led to complex product mixtures, with no practical substrate selectivity. However, if in analogous experiments several

Design of indole- and MCR-based macrocycles as p53-MDM2 antagonists

• Constantinos G. Neochoritis,
• Maryam Kazemi Miraki,
• Eman M. M. Abdelraheem,
• Ewa Surmiak,
• Tryfon Zarganes-Tzitzikas,
• Beata Łabuzek,
• Tad A. Holak and
• Alexander Dömling

Beilstein J. Org. Chem. 2019, 15, 513–520, doi:10.3762/bjoc.15.45

• synthesis was accomplished by a rapid, one-pot synthesis of indole-based macrocycles based on Ugi macrocyclization. The reaction of 12 different α,ω-amino acids and different indole-3-carboxaldehyde derivatives afforded a unique library of macrocycles otherwise difficult to access. Screening of the library

• -pocket as shown by our docking studies (Figure 1A,B, Figure S4 in Supporting Information File 1). Thus, extending our previous work [13], the Leu26 subpocket was probed by utilizing the different ring sizes and the different heteroatoms (oxygen or sulfur) of our macrocyclic library. In addition, the

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• synthesis of a novel library of 9-alkyl-2-amino-6-triazolylpurine derivatives. Thus, copper-catalyzed azide–alkyne 1,3-dipolar cycloaddition reaction of compounds 6a–c with different para-substituted phenylacetylenes produced the expected compounds 7a–f, 8a–f and 9 (Scheme 1). The yields of 1,3-dipolar

• biocompatibility could be applied for the cell staining in fluorescence microscopy. Applications in the cell studies The newly prepared compound library with purine and 7-deazapurine derivatives was submitted to the screening of their biological activity. The compounds of interest were studied on two cancer cell

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• combinatorial library [88]. The work carried out by Davis and co-workers led to the metabolic incorporation of unnatural amino acids (uAAs) bearing a terminal alkene as CM substrates for protein modification [89]. The authors investigated the possibility to incorporate methionine (Met) analogues in a Met

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• heterocycles; thioamides; Introduction Omnipresent among natural compounds and drugs, the indole core is a privileged scaffold for library design and drug discovery [1]. Its dioxo derivative, isatin (1H-indole-2,3-dione), is an important building block for the construction of diverse indole-based compounds

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• olefin metathesis, a small library of indenylidene and Hoveyda-type complexes bearing unsaturated unsymmetrical NHCs combining a flexible cycloalkyl moiety and a mesityl unit as N-substituents (85–89, Figure 18) was synthesized by Mauduit and co-workers [34]. These systems were tested in the RCM of

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• these established methods necessary. Examples from the past 15 years include transition metal-catalyzed transformations [21][22][23], solid-phase synthesis directed at combinatorial library design [24] and organocatalytic annellation reactions [25][26]. Sparked by our interest in the development and

Synthesis of indole–cycloalkyl[b]pyridine hybrids via a four-component six-step tandem process

• Muthumani Muthu,
• Rakkappan Vishnu Priya,
• Abdulrahman I. Almansour,
• Raju Suresh Kumar and
• Raju Ranjith Kumar

Beilstein J. Org. Chem. 2018, 14, 2907–2915, doi:10.3762/bjoc.14.269

• -carbonitrile hybrids 15–18 were isolated (Table 4). The structure of all the hybrid heterocycles 15–18 was elucidated using NMR spectroscopy and in the case of 16f the structure was further confirmed from single crystal X-ray studies (Figure 4) [74]. Conclusion The syntheses of a library of novel indole

Protein–protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics

• Laura Carro

Beilstein J. Org. Chem. 2018, 14, 2881–2896, doi:10.3762/bjoc.14.267

• the peptide-binding pocket of the β-clamp, they carried out a fluorescence anisotropy titration screening of the Rockefeller University chemical library containing 30,600 polar organic compounds which led to the discovery of RU7 (9, Figure 3) with an inhibition constant of 10 μM. Pleasingly, it was

• ECSC 10 (Figure 3), which displayed an IC50 in the low micromolar range (IC50 = 40 μM). X-ray crystallography studies revealed that this biphenyl oxime derivative 10 also occupies subsite I of the β-clamp [61]. In 2014, the Zenobia’s First Pass Screen fragment library containing more than 350 fragments

• was screened by X-ray crystallography leading to the identification of four fragment hits. In an attempt to improve their binding affinities, another library was searched for compounds displaying similarity to these initial hits. After a docking-based screening followed by a fluorescence polarization

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

• Clémentine Minozzi,
• Jean-Christophe Grenier-Petel,
• Shawn Parisien-Collette and
• Shawn K. Collins

Beilstein J. Org. Chem. 2018, 14, 2730–2736, doi:10.3762/bjoc.14.251

• conversion of an alcohol to bromide involved screening a wide variety of structurally varied complexes. Our group has previously demonstrated that the nature of each ligand influences the physical and photophysical properties as well as catalytic activity of the resulting catalyst (Figure 2) [27]. A library

• adapted to continuous flow using purple LED reactors. The batch and continuous flow processes were all made possible due to the ability to screen highly modular copper-based complexes for photocatalysis. Alcohol→bromide functional group transformations. Ligands used in the library generation of

• heteroleptic copper(I)-based complexes for photocatalysis. Evaluation of the library of copper-based complexes in photocatalytic alcohol→bromide conversion. Reactions irradiated with 394 nm light (pink) or 450 nm (blue). Front entries without an indicated phosphine ligand pertain to homoleptic Cu(diamine)2BF4

Assembly of fully substituted triazolochromenes via a novel multicomponent reaction or mechanochemical synthesis

• Robby Vroemans,
• Yenthel Verhaegen,
• My Tran Thi Dieu and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2689–2697, doi:10.3762/bjoc.14.246

• product 6. As variation of the substituents on the three different starting materials is necessary to obtain a diverse library, there is one main limitation to overcome. The first step of the reaction relies on the fluidity of salicylaldehyde (1a) to liquefy the reaction mixture. Salicylaldehyde analogs

Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

• Stephen M. Geddis,
• Teodora Coroama,
• Suzanne Forrest,
• James T. Hodgkinson,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

• , traditionally considered to be challenging scaffolds. Screening of the library provided valuable insights into the structure–activity relationship of the bacterial growth defects, and suggested that selectivity between bacterial species should be attainable. Furthermore, a structurally related series of

• substituent in our previous study, for which these copper-catalysed conditions resulted in dimerization [11]. Following the discovery of this substrate-dependent dichotomy with respect to optimal reaction conditions, the entire library of compounds was successfully cyclised. Whilst the yields ranged from low

• heterocyclisation with concomitant N–>N’ methyl transfer. With the library of natural products and analogues in hand, our attention turned to their biological activity. It was desired to further explore the growth defects which had been previously noted for natural products 1–4 against E. coli and S. aureus, and so

Non-native autoinducer analogs capable of modulating the SdiA quorum sensing receptor in Salmonella enterica serovar Typhimurium

• Matthew J. Styles and
• Helen E. Blackwell

Beilstein J. Org. Chem. 2018, 14, 2651–2664, doi:10.3762/bjoc.14.243

• identify an expanded range of synthetic ligands for SdiA. Herein, we report the screening of a focused library of AHL analogs for activity in the SdiA receptor from S. Typhimurium. Compound efficacies and potencies were measured in agonism and antagonism assays using an SdiA luminescence reporter system

• Selection of the AHL library for screening. We sought to examine a range of AHL-type scaffolds for activity in SdiA. We selected a series of sub-libraries from our in-house compound collections for analysis with demonstrated activities in other LuxR-type receptors, including TraR from Agrobacterium

• tested is shown in Supporting Information File 1. An overview of the structures in each sub-library is provided below. Sub-libraries A and H contained AHLs with differing acyl tail lengths and oxidation levels at the tail β-carbon, including many naturally occurring AHLs [51][55]. The B and D sub

The design and synthesis of an antibacterial phenothiazine–siderophore conjugate

• Abed Tarapdar,
• James K. S. Norris,
• Oliver Sampson,
• Galina Mukamolova and
• James T. Hodgkinson

Beilstein J. Org. Chem. 2018, 14, 2646–2650, doi:10.3762/bjoc.14.242

• chelating groups of the siderophore. The synthesis is readily amenable to the preparation of analogues whereby the siderophore component of the conjugate can be modified. The route will be used to prepare a library of siderophore–phenothiazine conjugates for full biological evaluation of much needed new

• antibiotic delivery. A library of mono-, bis- and tris-catechol phenothiazine–siderophore conjugates are currently being prepared using this route. Their synthesis and MIC values against pathogenic mycobacteria, Gram-negative bacteria and Gram-positive bacteria, along with compound 11, will be reported in

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• showed activity in the nanomolar range (Figure 8). Furthermore, a tetrazolopyrimidinone scaffold 19 has been reported to inhibit PqsD through a putative blockade of the CoA binding site [61]. The Böttcher group used a library of HHQ as well as PQS analogues to screen for PqsD inhibition [62]. To this end

• . In order to block the thioesterase activity of the enzyme, a library of 500 fragments was screened via differential scanning fluorimetry (DSF) and the hit fragments 24–26 (Figure 11) were further validated using isothermal titration calorimetry (ITC) [66]. Binding to PqsE could be confirmed with KD

• the same group used docking studies to select compounds from a quinolone-based compound library (Figure 17). The best fitting compounds 37–40 were then evaluated in a whole bacterial cell-based P. aeruginosa screening with IC50 values in the low micromolar range. Additionally, they showed that

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• heterocyclization. In order to enlarge the compound library available for pharmacological studies, the 3β-OH analogs 7a–j of the primary products 6a–j were also synthesized through simple alkaline deacetylation (Scheme 2, Table 1). The structures of all synthesized compounds were characterized by 1H and 13C NMR