Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• of [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazine fragment on antifungal activity of the synthesized compounds, we have tested the activity of their analogues, unannulated 1,2,4,5-tetrazines 2c,g, containing the amidine moiety, and isomeric [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines. For a comparative

• analysis of antifungal activity, the previously described [37] 3-methyl- and 3-phenyltriazolo[4,3-b][1,2,4,5]tetrazines 10a,b were used as structural analogues of compounds 3a,b. Furthermore, in the reactions of compound 10a with methanol, heptylamine and morpholine, new derivatives 11a–c have been

• -pyrazol-1-yl)-3-methyl-[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine (10a) with nucleophiles. In vitro fungistatic activity of [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines 3a–k, 4a–c, 5a–c and their analogues. Supporting Information Supporting Information File 28: Experimental part. Acknowledgements Analytical

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

• neuraminidase in relation to the analogues bearing hydrophobic substituents and ca. 5% for more polar substituents. These results suggest that polarity changes are less tolerated by neuraminidase due to the big difference in impact of hydrophobicity upon inhibition, thus indicating a simple approach to

• developed to date. The most potent TcTS inhibitors described are non-carbohydrate-based molecules (anthraquinones [14], chalcones and quinolones [15]) with low micromolar activity, whereas sialic acid-based analogues typically show high millimolar inhibitory activity [16], with few exceptions such as a

• sterically hindered active site (comparison shown with black arrows – Figure 5C and Figure 5D), which in turn conferred selectivity towards the neuraminidase. From the analogues perspective, the absence of TcTS inhibition could be also attributed to the lack of flexibility of the substituents rather than

Diametric calix[6]arene-based phosphine gold(I) cavitands

• Gabriele Giovanardi,
• Andrea Secchi,
• Arturo Arduini and
• Gianpiero Cera

Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21

• calix[6]arene scaffold, we carried out the synthesis of three monomeric gold catalyst analogues A’,B’,C’(AuCl). The synthesis of these compounds was performed using the previously optimized protocol, starting from a 4-(octyloxy)aniline intermediate (Scheme 2). Subsequently, due to the general interest

• .), CH2Cl2, 0 °C to rt [A, 60%; B, 55%, C, 53%); iii) (Me2S)AuCl in CH2Cl2, 0 °C to rt (A(AuCl)2, 93%; B(AuCl)2, 74%; C(AuCl)2, 69%). Synthesis of the monomeric gold catalyst analogues A’,B’,C’(AuCl). Conditions: i) diphenylphosphinobenzoic acid, EDC∙HCl, DMAP (cat.), CH2Cl2, 0 °C to rt (A’, 71%; B’, 76%; C

Asymmetric organocatalytic Michael addition of cyclopentane-1,2-dione to alkylidene oxindole

• Estelle Silm,
• Ivar Järving and
• Tõnis Kanger

Beilstein J. Org. Chem. 2022, 18, 167–173, doi:10.3762/bjoc.18.18

• using CPD as a precursor for high value-added fine chemicals such as a homocitric acid lactone was published by our group [19]. Since then we have developed synthetic pathways for lycoperdic acid [20] and nucleoside analogues [21] starting from CPD. The organocatalytic methods for the synthesis of

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• closely related analogues, one containing a bromo substituent and the other one incorporating an 8-membered instead of a 7-membered ring. The key transformation in this four-step synthesis, with an overall yield of 29%, is the Fischer indole reaction of 2-nitrophenylacetyl acetoacetate with 1-benzyl-1

• scaffolds with versatile medicinal properties, including anti-Alzheimer, anti-inflammatory, anticancer, antidiabetic, and antileishmanial activity [1]. Since the first synthesis of paullones (scaffold A in Figure 1) in 1992 [2], and disclosure of their Cdk inhibiting potential, several other analogues were

• ) was confirmed by the successful preparation of two closely related analogues, namely 3b, bearing a bromo substituent at position 11 of the backbone C (Scheme 6), and 3c, with an 8-membered azocinone ring instead of the 7-membered one. The synthesis of 3b started with a Fischer indole synthesis from

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

• Sandeep Kumar,
• Jyotirmoy Maity,
• Banty Kumar,
• Sumit Kumar and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2022, 18, 95–101, doi:10.3762/bjoc.18.10

• chemoenzymatic method was found to be superior over the chemical method in respect of the number of synthetic steps and overall yield of the final product. Keywords: bicyclic AZT analogues; bridged homoarabinofuranosylpyrimidine nucleosides; chemical pathway; Lipozyme® TL IM; regioselective enzymatic

• acetylation; Introduction In the last few decades, modification of nucleoside/nucleotide analogues has been a field of keen interest to researchers due to their therapeutic properties for treatment of cancer, viral and microbial infections [1][2][3][4][5][6][7][8][9]. The very first cytotoxic

• chemotherapeutic agents used for the treatment of cancer were nucleoside analogues and nucleobases [10]. Azidothymidine (1, AZT) was the first approved drug for the treatment of human immunodeficiency virus (HIV) [11][12]. Subsequently, a large number of sugar modified nucleosides, such as ddC (zalcitabine) [13

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• biological activities [6][7]. Moreover, they can be used as starting substances for different heterocycles, as precursors for the synthesis of polymers, as potential pharmacons, for the synthesis of natural products or analogues, and also as building blocks in drug research [8][9][10][11]. Furthermore, some

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• . All cases will be covered throughout the text. Synthesis of 4-amino-β-naphthoquinones and analogues from β-NQS After the first discovery that β-NQS reacts quickly with amines to form colored products in good yields, this reagent became quite popular in quantitative analytical determinations of some

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• of the three cleavage sites are blocked by the macrocycle. Accelerated molecular dynamics simulations verified a significantly higher degree of helicity for SMC stapled peptide P5 compared to the linear analogues P6 and aAxWt, which is in accordance with the experimental data obtained from CD and

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• , which leads to formyl products from formal oxidative cleavage of a C=C bond. Our interest in vinylogous analogues of 2-nitroaryl photoreactive groups stems from studies into alkenylboronic acid reagents for Chan–Lam-type modification of peptide backbone N–H bonds, directed by a proximal histidine

• . C–O cleavage, Figure 1A) through H-atom abstraction from a photoexcited intermediate, which produces an oxonium-type intermediate (in brackets). Hydrolysis of this intermediate then affords an alcohol product. Recently [16][17], we demonstrated that vinylogous analogues of this mechanism (Figure 1B

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• hoshinoamide A and other highly methylated polypeptide analogues. Our strategy was also helpful to further study its antimalarial activity. Structure-and-activity and functional studies with the fluorescent-labeled analogs are currently under investigation in our lab. Experimental General experimental

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• ]. In the same year, the Du group investigated the FeCl2·4H2O decarboxylative radical alkylative cyclization of cinnamamides 131/134 as an expedient approach towards dihydroquinolinone 133 and pyrrolo[1,2-a]indole 135 analogues in good yield and excellent diastereoselectivity (Scheme 27) [120]. In terms

A tribute to Carsten Schmuck

• Jochen Niemeyer,
• Ivo Piantanida and
• Thomas Schrader

Beilstein J. Org. Chem. 2021, 17, 2795–2798, doi:10.3762/bjoc.17.190

• into account particular features of “Carsten’s GCP” unit, or related analogues, he would propose several feasible structural modifications, which could provide novel properties of scientific interest. Finally, upon mutually agreeing on the next generation of new compounds, he would always take the

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

• about 2,500 known structures. Among these are “simple” benzylisoquinolines and, even more important, their 1,2,3,4-tetrahydro analogues and bisbenzylisoquinolines derived thereof, as well as more complex tetra- and pentacylic ring systems (aporphines, protoberberines, cularines, morphinane-type

• ][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

• should lead to an N-methyl group and to reductive cleavage of the carbonate-protected phenol(s); route B is based on treatment with an alkyllithium compound [26], which should remove all ethoxycarbonyl groups and provide N-nor analogues of the products obtained in route A (Figure 3). The required

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• sulfur atom at the 3’-position, these compounds have proved to be structurally potent nucleoside analogues, and the best example is BCH-189. The majority of methods traditionally involves the chemical modification of nucleoside structures. It requires the creation of artificial sugars, which is

• -oxathiolane nucleosides via resolution methods. The chemical as well as enzymatic procedures are reviewed and segregated in this review for effective synthesis of 1,3-oxathiolane nucleoside analogues. Keywords: chiral auxiliaries; enzymes; Lewis acids; N-glycosylation; 1,3-oxathiolane sugar and nucleosides

• . These molecules play a significant role in replication, transmission, and transcription of genetic material in life forms [1]. Structural analogues similar to the naturally occurring 2'-deoxynucleosides and ribonucleosides, the DNA and RNA building blocks, respectively, are expected to mimic their

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

• Tobias Klein,
• Franka V. Gruschwitz,
• Maren T. Kuchenbrod,
• Ivo Nischang,
• Stephanie Hoeppener and
• Johannes C. Brendel

Beilstein J. Org. Chem. 2021, 17, 2621–2628, doi:10.3762/bjoc.17.175

• the spherical analogues with regard to blood circulation time, drug loading, and tumor penetration abilities [1][2][3]. However, the straightforward preparation of cylindrical polymer aggregates with defined and reproducible length still remains challenging but represents a prerequisite for the

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• catalyst containing the chiral bisoxazoline ligand (S,S)-8 led to the α-ketol rearrangement product 7 in 70% yield and 68% ee (Figure 3) [5]. The study further demonstrated the effectiveness of the catalyst for a series of analogues of 6 bearing various replacements for the phenyl group, often proceeding

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• with the microwave-assisted synthesis of 2,3-dihydro-1H-pyrrolizines from pyrrolidine-based enaminones suggested that the technique might also be suitable for preparing 5,6,7,8-tetrahydroindolizine analogues from the corresponding piperidine systems. In a preliminary investigation we prepared three

• the six-membered analogues, which readily lose the exocyclic double bond to give the iminium system 27 upon essentially irreversible protonation. Is this perhaps another example of the lower reactivity and greater relative stability of double bonds exo- to five-membered rings when compared with their

• 5,6,7,8-tetrahydroindolizines 26, respectively, when subjected to microwave heating with silica gel in suitable solvents. The enaminone acted as an electrophile in these cyclization reactions rather than as a nucleophile, as had previously been found with N-phenacyl analogues [18]. The formation of

Synthesis of new substituted 7,12-dihydro-6,12-methanodibenzo[c,f]azocine-5-carboxylic acids containing a tetracyclic tetrahydroisoquinoline core structure

• Agnieszka Grajewska,
• Maria Chrzanowska and
• Wiktoria Adamska

Beilstein J. Org. Chem. 2021, 17, 2511–2519, doi:10.3762/bjoc.17.168

• ]nonane, isolated from Papaveraceae and Ranunculaceae species. Natural isopavines (e.g., amurensinine (I), and O-methylthalisopavine (II), Figure 1) as well as their synthetic analogues have attracted much attention [4][5] because of their interactions with the receptors in the central nervous system

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• optoelectronic properties [32][35][36][37]. Acridines, as aza-analogues of anthracene have obtained much attention in the field of organic light emitting diodes [38][39][40][41]. While considerable attention has been devoted to the photophysical properties of acridines, not much work has been reported related to

• their partially hydrogenated analogues, even though they were used as electron-donor groups for OLED applications [42][43]. On the other hand, tetrahydroacridines have received much attention in medicinal chemistry, due to their ability to inhibit topoisomerase enzymes and block the DNA transcription

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• design new synthetic methodologies for reproducing these natural products and their analogues as well as to develop new pharmaceuticals from them. Structures of brevipolides A–O (1 – 15). Retrosynthetic analysis of brevipolide H (8) by Kumaraswamy. Attempt to synthesize brevipolide H (8) by Kumaraswamy

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• agents; carboxylate analogues; 1H-1,2,3-triazole analogues; metronidazole; synthesis; Introduction Metronidazole (1) is an important antimicrobial agent which has been clinically used successfully for a long time. It was originally used for the treatment of infections caused by Trichomonas varginalis

• cost-effective drug. Due to its impressive antimicrobial activity and limited adverse effect metronidazole (1) has been considered as a “Gold Standard” antibiotic (Figure 1). However, to avoid the problem related to clinical resistance to this antimicrobial agent some novel and improved analogues of

• 1H-1,2,3-triazole was based on its known activities and its broad range of applications in biochemical, pharmaceutical, biomedicinal and materials sciences [4][5]. Results and Discussion Chemistry: synthesis of 1H-1,2,3-triazole analogues of metronidazole Metronidazole (1) has a free primary hydroxy

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• 14 known analogues (4–14 and 17–19). The structural elucidation of the new compounds was performed through the analysis of their NMR, HRMS, and ECD spectra and by chemical methods. All isolated compounds were tested for their antineuroinflammatory and neuroprotective activities. Keywords: Aleurites

Base-free enantioselective S_N2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis

• Mili Litvajova,
• Emiliano Sorrentino,
• Brendan Twamley and
• Stephen J. Connon

Beilstein J. Org. Chem. 2021, 17, 2287–2294, doi:10.3762/bjoc.17.146

• employment of benzyl bromides bearing electron-withdrawing groups led to products with moderate ee in the cases of para-substituted analogues (Table 2, entries 4 and 5) while an increase in enantioselectivity, up to 79% ee, was observed using meta-substituted variants (Table 2, entries 6 and 7). To our

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• polymers, such as PDMAPS and its structural analogues [88][89][90][91], and on the other hand, polymers with strong hydrogen acceptor and donor units, like the uncharged PNAGA [92][93][94][95][96], show a pronounced UCST. In contrast, the solubilization process of a polymer with LCST behavior is an