On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• to be a helpful strategy in the synthesis of compound LY2784544 (41), a potent inhibitor of Janus kinase 2 that is under clinical trials for the management of myeloproliferative disorders (Scheme 14B) [109][110]. Beyond that, this class of molecules (imidazopyridazines) are known to present a potent

• effects (85–89, Scheme 31A), such as antioxidant, α-amylase inhibitor, anticancer, and anti-inflammatory activities [164]. The reaction was promoted by non heme-Fe catalyst, behaving similarly to the bioinspired iron catalyst in a redox-selective way. The combination of Fe(phen)3(PF6)3 and tertiary

• anilines afforded α-aminoalkyl radicals that could be coupled with a wide range of electrophilic partners to afford the products in moderate to good yields. The new reaction was also used in the first step of the total synthesis of a caspase-3 inhibitor (90), and mechanistic investigations showed that O2

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

• since it was shown to be an effective inhibitor of tumor necrosis factor-alpha (TNF-α) production by preventing the activation of TLR4 by lipopolysaccharide (LPS) and was thus proposed for potential use against atherosclerosis [67]. Furthermore fumigaclavine C has also proven effective against MCF-7

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• derivatives of complex biologically active compounds and natural products were evaluated in the late-stage benzylic C–H amination process using MnIII(ClPc) (18) and iminoiodinane. For example, the amination of FKGK11 (17a), a potent inhibitor of iPLA2, proceeded smoothly in a moderate yield. Notably

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• spectrum of biological activities [1][2][3]. Some representative compounds comprising this skeleton are illustrated in Figure 1. Cycloolivil (Figure 1, 2) [4], which is isolated from the stem bark of Olea europaea, has been recognized as inhibitor of cyclic AMP dependent phosphodiesterase, can act as a Ca2

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• -pyrido[3,4-b]indole (β-carboline) is the most naturally abundant, present for instance, in the alkaloid harmine, a well-known selective inhibitor of monoamine oxidase-A (MAO-A) [1]. On the contrary, 5H-pyrido[4,3-b]indoles (γ-carbolines) are comparatively less examined, although these heterocycles have

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• -nucleoside reverse transcriptase inhibitor (NNRTI) doravirine (49) in flow (Scheme 5) [100]. The aldol reaction of an aromatic ester 44 with a vinylogous ester 45 was achieved in a continuous manner, yielding the hydroxyl adduct, 46, in 85% yield within just a 15 second residence time. Here, a slightly

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• . Final reaction with di-tert-butyl dicarbonate led to functionalized 2-piperidinones 136 [127]. These compounds are interesting reaction intermediates because they can be transformed by conventional reactions into, for instance, compound L-685,458 (137), an inhibitor of γ-secretase, with potential

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• pancreatic carcinoma and triple-negative breast cancer (Scheme 23B) [55]. Konteatis et al. adopted a similar approach by using the direct fusion for the preparation of bisdifluorocyclic biguanides as IDH1/2 inhibitor intermediates (Scheme 23C) [56]. However, sodium dicyanamide has been mainly used as an

• reaction by using hydroxylamine as a nucleophile to substitute the thiomethyl group, followed by pyrrolidine addition on the cyano group to form the corresponding hydroxybiguanidine that was used as an IDO-1 inhibitor (Scheme 37) [77]. In conclusion, despite the obvious synthetic constraints such as the

Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

• Rashmi Singh,
• Tomas Horsten,
• Rashmi Prakash,
• Swapan Dey and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 977–982, doi:10.3762/bjoc.17.79

• cancer cell lines [12][13]. Fluoroquinophenoxazines 2 have been used as telomerase inhibitors in anticancer research [14]. Furthermore, benzofuroisoindoles 3 were part of a kinase inhibitor study [15]. Photobiologically active psoralene (linear furocoumarin) dibenzofurans 1 and angular furanocoumarin

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• produced 90. Similarly, the reaction of 91 produced all-cis-2,3,6-trisubstituted tetrahydropyran 93. The application of this reaction was further extended by an exceptionally concise formal total synthesis of the nuclear export inhibitor (+)-ratjadone A, as shown in Scheme 20. Stereoselective Prins

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• attributes, nuclease stability, and hybridization to single and double stranded nucleic acid targets have led to studies to investigate 3'-NP DNA for antisense and antigene purposes. For example, as an antisense agent in the treatment of human leukemia [67], as an inhibitor of transcription elongation

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• atorvastatin, a potent HMG-CoA reductase inhibitor. Dömling and co-workers efficiently demonstrated an Ugi-based MCR approach towards the synthesis of atorvastatin in four steps ruling out the lengthy seven step protocol, and paving a rapid entry to the drug discovery market [12]. Alternatively, microwave

• double bonds. Numerous natural compounds containing pyrans and benzopyrans (fused pyrans) are identified. Epicalyxin (45) is used as an anticancer agent against human HT-1080 fibrosarcoma and murine 26-L5 carcinoma. Laninamivir (46) is a pyran-based drug used as a neuraminidase inhibitor and zanamivir

β-Lactamase inhibition profile of new amidine-substituted diazabicyclooctanes

• Zafar Iqbal,
• Lijuan Zhai,
• Yuanyu Gao,
• Dong Tang,
• Xueqin Ma,
• Jinbo Ji,
• Jian Sun,
• Jingwen Ji,
• Yuanbai Liu,
• Rui Jiang,
• Yangxiu Mu,
• Lili He,
• Haikang Yang and
• Zhixiang Yang

Beilstein J. Org. Chem. 2021, 17, 711–718, doi:10.3762/bjoc.17.60

• therapy employs the combination of an existing antibiotic with a β-lactamase inhibitor (BLI). A few of BLI/BL combinations have been approved [6] so far for clinical applications by different countries, clavulanic acid/amoxicillin (augmentin) [7][8][9] being the first one, while others are in clinical

• led the researchers to develop second generation β-lactamase inhibitors, finally succeeded with the approval of avibactam and relebactam as non-β-lactam-based BLIs. Avibactam proved potent as inhibitor of Klebsiella pneumoniae carbapenemases (KPCs), AmpCs and some of class D β-lactamases [18] is now

• different kinds of substituents (R) introduced in the final compounds A1–23 are depicted in Table 1. In vitro antibacterial activities of compounds A1–23 were determined first without combining the compounds with an antibacterial drug and the minimum inhibitor concentration (MIC) of each compound was

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• high anticonvulsant activity after tests in silico and in vivо [7]. Moreover, compounds C and D reveal high activity as casein kinase 2 (CK2) inhibitor and high antitumor activity which makes compounds to be promising anticancer drugs [8]. There are quite a few methods for the synthesis of the

The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst

• Deniz Tözendemir and
• Cihangir Tanyeli

Beilstein J. Org. Chem. 2021, 17, 494–503, doi:10.3762/bjoc.17.43

• inhibitor activity [33]. Due to the shown biological attractiveness of those 1,3-biarylsulfanyl derivatives, the enantioenriched products can serve as important building blocks for new drugs. The sulfide moiety of β-naphthyl-β-sulfanyl ketones can be oxidized to form sulfones. Despite that sulfones were

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

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

• molecule libraries against a bacterial TGase, an iminocyclitol was conjugated with a pyrophosphate mimic. After in situ screening, the first potent iminocyclitol-based inhibitor against bacterial TGases was efficiently developed [27]. The synthesis of N-pyrrolidine-derived β-phosphonodepsipeptides 64 is

• 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

• general method to prepare these compounds [58]. (R)-1-Amino-3-methylbutylphosphonic acid ((R)-204), a phosphonic ʟ-Leu analogue, is a potent inhibitor of the metalloenzyme leucine aminopeptidase. Racemic dibenzyl 1-hydroxy-3-methylbutylphosphonate (203), an oxyanalog of phosphonic leucine, was partially

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• inhibitor screening can be expected. In the field of 19F NMR protein conformational studies another area that has seen increasing attention is that of membrane proteins (MPs). Despite their physiological importance, analysis of the structural biology of MPs is significantly limited due to difficulties

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

Novel library synthesis of 3,4-disubstituted pyridin-2(1H)-ones via cleavage of pyridine-2-oxy-7-azabenzotriazole ethers under ionic hydrogenation conditions at room temperature

• Romain Pierre,
• Anne Brethon,
• Sylvain A. Jacques,
• Aurélie Blond,
• Sandrine Chambon,
• Sandrine Talano,
• Catherine Raffin,
• Branislav Musicki,
• Claire Bouix-Peter,
• Loic Tomas,
• Gilles Ouvry,
• Rémy Morgentin,
• Laurent F. Hennequin and
• Craig S. Harris

Beilstein J. Org. Chem. 2021, 17, 156–165, doi:10.3762/bjoc.17.16

• investment in route scouting and optimization. This full paper focuses on the synthesis issues that we encountered during our route exploration and the original solutions we found that helped us to identify two optimized library-style processes to prepare our large kinase inhibitor library. Keywords: 7

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• iminosugar derivatives may be less obvious. Several pharmaceuticals are based on this scaffold including the glucose-derived nojirimycin, an antibiotic and glycosidase inhibitor [26] and 1-deoxygalactonojirimycin, known under the trade name Galafold®, which is utilized for the treatment of the Fabry disease

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• as monofluorinated and trifluoromethylated arenes or aliphatics [1][2][3][4]. Recent progress in difluoromethylene chemistry successfully led to the finding of bioactive compounds such as pantoprazole, a proton pump inhibitor [5], and AFP-07, a prostaglandin I2 receptor-selective agonist [6][7][8

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• strength dependence is β-lactamase and its protein inhibitor BLIP, where binding decreases significantly as the salt concentration increases [53]. Chen et al. analysed the structural and thermodynamic data of 113 heterodimeric complexes and discussed the correlation between binding affinity and amount of

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

• Joon Min Cha,
• Dong Hyun Kim,
• Lalita Subedi,
• Zahra Khan,
• Sang Un Choi,
• Sun Yeou Kim and
• Chung Sub Kim

Beilstein J. Org. Chem. 2020, 16, 3078–3085, doi:10.3762/bjoc.16.257

• synthase (NOS) inhibitor ʟ-NMMA was employed. Graded sodium nitrite solutions were utilized to determine the nitrite concentrations. An MTT assay was used for the cell viability assay. Nerve growth factor and cell viability assays. Analogous as described in [13]. The C6 glioma cells (Korean Cell Line Bank

Secondary metabolites of Bacillus subtilis impact the assembly of soil-derived semisynthetic bacterial communities

• Heiko T. Kiesewalter,
• Carlos N. Lozano-Andrade,
• Mikael L. Strube and
• Ákos T. Kovács

Beilstein J. Org. Chem. 2020, 16, 2983–2998, doi:10.3762/bjoc.16.248

• ][44]. It is presumed that the antifungal plipastatin, expressed from the ppsA-E gene cluster, acts as an inhibitor of phospholipase A2, forming pores in the fungal membrane and causing morphological changes in the fungal membrane and cell wall [45][46]. This antifungal potential was demonstrated