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

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

• . Tacrine (1) is an acridine derivative used in the treatment of Alzheimer’s disease. A plethora of acridine derivatives have been synthesized and clinically proved with various biological activities such as ethacridine (antibacterial drug; 2), acranil (antiviral drug; 3) and quinacrine (antimalarial agent

• (47) for prevention of influenza A and B. β-Lapachone (48) shows diverse biological activities like anticancer, antibacterial and anti-inflammatory activities [53]. Benzopyrans and naphthopyrans represent a class of fused pyrans that has been studied for antimicrobial effects (49 and 50, Figure 4) [54

• 78 (Scheme 29). 6.2 Fused pyrimidines Fused pyrimidines represent an important class of heterocycles with potential biological activities such as antidiabetic (79), antiviral (80), anti-inflammatory (81, 82), anticancer (83), antibacterial (84) and antiplatelet (85) [75][76][77][78][79] with an

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

•  1). These pyrrolo[2,3-c]quinolines have been demonstrated to show antimalarial and antibacterial biological activities [2][3][4]. Thus, the development of a convenient and efficient synthetic route to the pyrrolo[2,3-c]quinoline skeleton has attracted considerable attention from organic and

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• , antihypertensive, anti-Parkinson, anti-inflammatory, anticonvulsant, vasodilatory, antidiabetic, antitubercular, antifungal, and antibacterial activities [32][33][34][35][36][37][38], pH-sensing [39], OLEDs [40], chemiluminescent materials [41][42], metal complexes (Figure 1) [43][44][45][46], liquid crystal [47

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

• -lactamase inhibitors. As part of our efforts, we have synthesized a series of DBO derivatives A1–23 containing amidine substituents at the C2 position of the bicyclic ring. These compounds, alone and in combination with meropenem, were tested against ten bacterial strains for their antibacterial activity in

• vitro. All compounds did not show antibacterial activity when tested alone (MIC >64 mg/L), however, they exhibited a moderate inhibition activity in the presence of meropenem by lowering its MIC values. The compound A12 proved most potent among the other counterparts against all bacterial species with

• MIC from <0.125 mg/L to 2 mg/L, and is comparable to avibactam against both E. coli strains with a MIC value of <0.125 mg/L. Keywords: amidine; antibacterial activity; β-lactamase inhibitors; diazabicyclooctane; synthesis; Introduction Survival stress posed by antimicrobial agents triggers multiple

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• -lactams are important lead compounds, e.g., derivatives with antibacterial activity were discovered, what gains importance with respect to the increasing bacterial resistance toward traditional β-lactam antibiotics [35][36][37][38][39]. Various synthetic pathways can be applied for the construction of the

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• ]. Fullerene-containing compounds with antiviral (various forms of influenza, herpes, HIV) [28][29][30], antibacterial [31][32][33], and anticancer activity [34][35] have been found among them. An important approach in this area involves the synthesis of complex- and covalent-bound fullerene derivatives with

Breakdown of 3-(allylsulfonio)propanoates in bacteria from the Roseobacter group yields garlic oil constituents

• Anuj Kumar Chhalodia and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 569–580, doi:10.3762/bjoc.17.51

• (Scheme 1A) [2]. The antibacterial principle in garlic was identified in 1944 by Cavallito et al. as allicin (5) [3], a formal oxidation product of disulfide 2. Not only 5, but also several other sulfur compounds from garlic are today known to exhibit diverse biological activities, including inter alia

• antibacterial, antifungal, antioxidant, anti-inflammatory, and anticancer effects [4]. Later on, also heterocyclic compounds including 2-vinyl-4H-1,3-dithiine (6) and 3-vinyl-3,4-dihydro-1,2-dithiine (7) were discovered [5]. The formation of these volatile sulfur compounds starts from alliin (9) [6], a non

Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines

• Geetanjali S. Sontakke,
• Rahul K. Shukla and
• Chandra M. R. Volla

Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42

• natural products [1][2][3][4], agrochemicals and pharmaceuticals having potent biological activities, such as antimalarial, antibacterial and anticancer activities [5][6][7][8][9][10][11]. Due to their wide range of applications, selective functionalization of quinolines at various positions has gained

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• ][3][4][5][6]. They are often used as antiviral, anticancer and antibacterial agents. Such intensive medicinal chemistry applications demand for constant development of novel synthetic methodologies. Frequently, the purine structure is modified in SNAr reactions with N- [7][8][9][10][11] and S

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• and B, are related as 7a-epimers that interconvert in aqueous solution to form a pH-dependent equilibrium ratio of the two [9]; they are weakly antibacterial and were shown to prolong “the survival period of mice inoculated with leukaemia L-120 cells” [7][8]. Although the clazamycins are not

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

• studies on this plant have reported triterpenoids [2][3][4][5][6][7][8] and phenolic compounds [2][9][10][11][12], and some of them showed anti-inflammatory and neuroprotective [13][14][15], antitumor [2], tissue factor inhibitory [5][9], antibacterial [8], antihemolytic [8], or antipruritic activities

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• Pseudomonas aeruginosa, a Gram-negative rod-shaped bacterium [5][6][7][8]. RL are built up by one or two rhamnose sugar units as well as one to three β-hydroxy fatty acids, which can also be unsaturated. These highly functional biomolecules exhibit interesting biological and antibacterial properties, as

Synthesis and investigation of quadruplex-DNA-binding, 9-O-substituted berberine derivatives

• Jonas Becher,
• Daria V. Berdnikova,
• Heiko Ihmels and
• Christopher Stremmel

Beilstein J. Org. Chem. 2020, 16, 2795–2806, doi:10.3762/bjoc.16.230

• -inflammatory [25], antibacterial [26][27], and anticancer reagents [28][29]. The latter property is mainly based on the binding interaction of berberine with nucleic acids and the resulting inhibition of topoisomerase and telomerase [2][30]. Most notably, berberine (1a) induces a strong growth inhibition in

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• actinomycete origin. For example, salinosporamide A, an antitumor drug candidate in clinical trials, is a proteasome inhibitor with an unusual γ-lactam-β-lactone bicyclic core produced by marine Salinospora tropica [10]. Abyssomicin, another example of uncommon polycyclic frameworks, is an antibacterial

Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides

• Dongsik Yang,
• Hongjian He and
• Bing Xu

Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221

• , peptide assemblies are being explored for a wide range of applications, including cell cultures [6], tissue engineering [7], drug delivery [8][9][10][11], antibacterial agents [12][13], regarding biomineralization [14][15], as collagen mimics [16], anisotropic hydrogels [17][18], for cancer therapy [19

Selective and reversible 1,3-dipolar cycloaddition of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with 1,3-diphenylprop-2-en-1-ones under microwave irradiation

• Alexander P. Molchanov,
• Mariia M. Efremova,
• Mariya A. Kryukova and
• Mikhail A. Kuznetsov

Beilstein J. Org. Chem. 2020, 16, 2679–2686, doi:10.3762/bjoc.16.218

• pyrazolidinone derivatives like LY186826 and its analogues with antibacterial activity [8][9][10][11][12]. The chemistry of azomethine imines has been actively investigated since the second half of the last century but their reactivity is still far less studied compared with nitrones or azomethine ylides – other

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• beneficial biological effects of OA, which include antioxidant, antidiabetic, anticancer, antibacterial, anti-inflammatory and antiviral properties [25][26][27][28][29][30]. Herein, we selected Q[8] as a host molecule and investigated its host–guest interactions with OA, as well as its effect on the

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• configurations were determined using the modified Mosher’s method and through comparisons of experimental and calculated electronic circular dichroism data. In addition, muyocopronone B (2) was found to exhibit a weak antibacterial activity against some Gram-positive bacteria. Keywords: azaphilones; endophytic

• ,10R,11R) stereoisomer. Finally, since a number of azaphilones have been reported to exhibit antimicrobial activity [5][23], muyocopronones A (1) and B (2) were screened for their antibacterial activity against five strains of Gram-positive bacteria, namely Staphylococcus aureus (PAGU 273T

• ), methicillin-resistant S. aureus (PAGU 841, MRSA), S. epidermidis (PAGU 283T), Enterococcus faecalis (PAGU 102T), and vancomycin-resistant E. faecalis (PAGU 100). Although muyocopronone B (2) exhibited an antibacterial activity against both antibiotic-resistant and antibiotic-susceptible strains, with minimum

pH- and concentration-dependent supramolecular self-assembly of a naturally occurring octapeptide

• Goutam Ghosh and
• Gustavo Fernández

Beilstein J. Org. Chem. 2020, 16, 2017–2025, doi:10.3762/bjoc.16.168

• , as mentioned above. The pH-responsive self-assembling behavior of peptides has a great importance in drug delivery, and since PEP-1 contains rich cationic residues, such as Arg, this system can be an interesting potential candidate for DDS and as an antibacterial agent [71]. Biocompatibility, drug

• delivery, and antibacterial studies are underway in our laboratory. Concentration-dependent secondary structure formation Apart from the pH-dependent self-assembly, we also investigated the role of the concentration on the self-assembly and secondary structure. As shown previously, the CD spectra at

Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups

• Xiaoyun Hu,
• Jianxin Guo,
• Cui Wang,
• Rui Zhang and
• Victor Borovkov

Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155

• ][2][3][4]. In the last decade, chiral DHPMs showed valuable pharmacological properties such as antiviral, antitumor, antibacterial, anti-inflammatory, and antihypertensive effects [5][6]. However, the individual enantiomers of DHPMs were found to exhibit different or even opposite pharmaceutical

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• )-configuration of the 3-hydroxy acid components in 1–4. These compounds showed no cytotoxicity but were weakly antibacterial against a fish ulcer pathogen, Tenacibaculum maritimum. The (2Z)-enoic acyl termini in 1–4 are precedented by 5, discovered from another Vibrio bacterium, and the (R)-configured short

• . Antibacterial assay The antibacterial activity was evaluated by a microculture technique described previously [20], except for a 1:100 reduction of the seeding density of T. maritimum NBRC16015. Cytotoxicity assay 3Y1 rat embryonic fibroblastic cells were maintained in low-glucose DMEM medium containing ʟ

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• antibacterial, antifungal, anticancer, or anti-inflammatory agents or even on the central nervous system [7][12][13]. Several routes have been reported to access these key compounds, the most developed being for the indole [14] derivatives using the Fischer indole synthesis involving sigmatropic rearrangements

Microwave-assisted efficient one-pot synthesis of N²-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

• Moustafa Sherief Moustafa,
• Ramadan Ahmed Mekheimer,
• Saleh Mohammed Al-Mousawi,
• Mohamed Abd-Elmonem,
• Hesham El-Zorba,
• Afaf Mohamed Abdel Hameed,
• Tahany Mahmoud Mohamed and
• Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

• -2,4-diamines; one-pot synthesis; X-ray crystallography; Introduction The family of triazines is of considerable interest in fields related to organic and medicinal chemistry. 2,4-Diaminotriazines are privileged scaffolds exhibiting diverse biological activities such as antibacterial [1], anti-HSV-1

• ]. Tetrazole derivatives exhibit a wide spectrum of biological activities as antibacterial [14], anticancer [15], anti-inflammatory [16], antidiabetic [17], antitubercular [18], and analgesic [19] agents. It is well established that many medical disorders can be caused as a result of defects at more than one

Antibacterial scalarane from Doriprismatica stellata nudibranchs (Gastropoda, Nudibranchia), egg ribbons, and their dietary sponge Spongia cf. agaricina (Demospongiae, Dictyoceratida)

• Cora Hertzer,
• Stefan Kehraus,
• Nils Böhringer,
• Fontje Kaligis,
• Robert Bara,
• Dirk Erpenbeck,
• Gert Wörheide,
• Till F. Schäberle,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2020, 16, 1596–1605, doi:10.3762/bjoc.16.132

• the genus Doriprismatica and scalarane-containing dictyoceratid sponges of the Spongiidae family. The results also indicate that D. stellata passes the scalarane metabolite on to its egg ribbons, most likely for protective purposes. The scalarane showed antibacterial activity against the Gram-positive

• bacteria Arthrobacter crystallopoietes (DSM 20117) and Bacillus megaterium (DSM 32). Keywords: antibacterial; Dictyoceratida; Nudibranchia; scalarane; sesterterpene; Introduction In habitats with intense competition and feeding pressure, such as coral reefs, sessile or slow-moving organisms commonly

• sesterterpene reported with a cyclopropane ring bridging the carbons C-3, C-22 and C-4 in ring A, and an acetoxy group at C-11 instead of C-12 in ring C (Figure 2). All ethyl acetate extracts, as well as the isolated new scalarane, showed antibacterial activity against the Gram-positive bacteria Arthrobacter