p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• amidoxime, ethanone oxime and aldoxime (VI, VII, VIII, R1 = p-pyridyl, Figure 1) as DNA photosensitizers. Based on our previous experimental results with o-, m- and p-pyridine oximes as carriers of the carboxylic [9] and sulfonic [11] ester conjugates, we proclaimed p-substituted pyridine ring as the most

• phenyl groups, bearing electron donating or withdrawing substituents, were synthesized and evaluated. Results and Discussion Synthesis All compounds were synthesized upon the reaction of the appropriate parent p-pyridine amidoxime 1 [58], ethanone oxime 14 [59] and aldoxime 21 [60] with the corresponding

• cm−1, characteristic of the amide moiety. This low carbonyl absorption probably indicates an intramolecular hydrogen bonding between NH2 and the oxime oxygen, which further verifies the Z-conformation of the amidoxime derivatives. The hydroxylimino structure is verified in 1H NMR spectra from the

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• ]pyrazines 230 which was used as synthetic precursor to generate several other substituted pyrazolo[3,4-b]pyrazine derivatives via amidoxime and carbohydrazide

Continuous-flow synthesis of highly functionalized imidazo-oxadiazoles facilitated by microfluidic extraction

• Ananda Herath and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2017, 13, 239–246, doi:10.3762/bjoc.13.26

• synthesis of S1P1 agonists (Scheme 1). Thus, a typical batch synthesis entails the formation of an amidoxime by reacting an arylnitrile with hydroxylamine in the presence of a base [29][30][31]. The amidoxime is then combined with a carboxylic acid derivative in the presence of a coupling reagent. The

• combined with EDC/HOBt/DIPEA (1:1:1) in a T-mixer. The synthesis of amidoxime was achieved by placing a second reactor (250 μL glass chip) in a heated silicone oil bath at 100 oC. The product stream was next introduced into a third reactor (1000 μL) and mixed with the stream exiting from the T-mixer at 150

• ) The first reaction, the formation of imidazo[1,2-a]pyridine-2-carboxylic acid, was carried out in a 1000 μL reactor (glass chip) at 100 °C. The acid exiting the first reactor was combined with EDC/HOBt/DIPEA (1:1:1, 0.5 M, DMA) in a T-mixer. The synthesis of amidoxime (ArCN/NH2OH·HCl/DIPEA (1.1:1:3

Robust C–C bonded porous networks with chemically designed functionalities for improved CO₂ capture from flue gas

• Damien Thirion,
• Joo S. Lee,
• Ercan Özdemir and
• Cafer T. Yavuz

Beilstein J. Org. Chem. 2016, 12, 2274–2279, doi:10.3762/bjoc.12.220

• through metal-free Knoevenagel nitrile–aldol condensation, namely the covalent organic polymer, COP-156 and 157. COP-156, due to high specific surface area (650 m2/g) and easily interchangeable nitrile groups, was modified post-synthetically into free amine- or amidoxime-containing networks. The modified

• hydroxylamine converted into amidoxime groups (COP-156-amidoxime). The COP-156-amine proved increased affinity towards CO2 with stronger binding energy, especially under moist conditions, reaching up to 7.8 wt % at 40 °C, a 2.1 wt % increase when compared to the original COP-156. Despite the promise

• different routes, either by reduction to the corresponding amine or reaction with hydroxylamine into an amidoxime. For the reduction, three reagents (LiAlH4, BH3–THF and BH3–Me2S) were screened. All reductions were chemically successful, but the textural properties of the modified networks were noticeably

3-Glucosylated 5-amino-1,2,4-oxadiazoles: synthesis and evaluation as glycogen phosphorylase inhibitors

• Marion Donnier-Maréchal,
• David Goyard,
• Vincent Folliard,
• Tibor Docsa,
• Pal Gergely,
• Jean-Pierre Praly and
• Sébastien Vidal

Beilstein J. Org. Chem. 2015, 11, 499–503, doi:10.3762/bjoc.11.56

• catalytic site has been accomplished through various families of glucose-based derivatives such as oxadiazoles. Further elaboration of the oxadiazole aromatic aglycon moiety is now reported with 3-glucosyl-5-amino-1,2,4-oxadiazoles synthesized by condensation of a C-glucosyl amidoxime with N,N

• ’-dialkylcarbodiimides or Vilsmeier salts. The 5-amino group introduced on the oxadiazole scaffold was expected to provide better inhibition of GP through potential additional interactions with the enzyme’s catalytic site; however, no inhibition was observed at 625 µM. Keywords: amidoxime; carbodiimide; glycogen

• on recent and unprecedented literature reports. Results and Discussion Synthesis of 3-glucosylated 5-amino-1,2,4-oxadiazoles The target GP inhibitor scaffold was obtained from the condensation of Vilsmeier salts with the C-glucosyl-amidoxime 3 [28] in the presence of a base. This condensation was

Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

• Mahabaleshwara Subrao,
• Dakshina Murthy Potukuchi,
• Girish Sharada Ramachandra,
• Poornima Bhagavath,
• Sangeetha G. Bhat and
• Srinivasulu Maddasani

Beilstein J. Org. Chem. 2015, 11, 233–241, doi:10.3762/bjoc.11.26

• -oxides to azomethines, nitriles and iminoesters. In the present study, we synthesized 1,2,4-oxadiazoles through amidoxime intermediates with substitutions at C-3 and C-5 positions. A moiety with a chiral center is attached to the phenyl ring (at C-5 position) of oxadiazole in the molecular structure. The

• -cyanobenzoate (2a) with hydroxylamine hydrochloride yielded the corresponding benzyl 4-(N'-hydroxycarbamimidoyl)benzoate (3a). This amidoxime (3a) is converted into benzyl 4-(5-(4-bromophenyl)-1,2,4-oxadiazole-3-yl)benzoate (5a) by treating it with 4-bromobenzoyl chloride in the presence of pyridine. Oxadiazole

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• linear fashion starting by amination of acetone cyanohydrin (3.19) followed by CBz-protection of the resulting amine and finally aminolysis of the nitrile 3.20 with hydroxylamine [90] (Scheme 34). The resulting amidoxime 3.21 was then reacted with dimethylacetylene dicarboxylate (DMAD) which upon heating

Synthesis and characterization of novel bioactive 1,2,4-oxadiazole natural product analogs bearing the N-phenylmaleimide and N-phenylsuccinimide moieties

• Catalin V. Maftei,
• Elena Fodor,
• Peter G. Jones,
• M. Heiko Franz,
• Gerhard Kelter,
• Heiner Fiebig and
• Ion Neda

Beilstein J. Org. Chem. 2013, 9, 2202–2215, doi:10.3762/bjoc.9.259

• 1,2,4-oxadiazoles is illustrated in Scheme 1. Using route (a), the amidoxime route, the carboxylic acid has to be employed in an activated form. The activated carboxylic acid can be prepared beforehand or in situ by several methods [34], e.g., as an acyl chloride or by the use of N,N

• ′-carbonyldiimidazole (CDI). In the first step the amidoxime is O-acylated with the activated derivative in a condensation reaction. The O-acylated amidoxime can be isolated or it can immediately undergo the cyclisation to the heterocyclic oxadiazole ring. This cyclodehydration reaction takes place by heating to

• -butylamidoxime and 4-nitrobenzonitrile under mild conditions. The results are summarized in Table 1. The optimized yield was 93% (Scheme 3) which makes this route more practical than the amidoxime route presented in Scheme 2 with a yield of only 59%. The structure of compound 2 was confirmed by X-ray structure