Search results for "Oxadiazole"
showing 10 items of 183 documents
Theoretical study of photoinduced ring-isomerization in the 1,2,4-oxadiazole series
2004
Abstract A theoretical study of photoinduced ring-isomerization of 3-amino-5-methyl- and 3-amino-5-phenyl-1,2,4-oxadiazoles is reported. The results well agree with the reported experimental data: in particular, they explain the ring-photoisomerization into the corresponding 2-amino-1,3,4-oxadiazoles through a ring contraction-ring expansion route; moreover, the occurrence of competing pathways involving both the ring contraction and the internal cyclization–isomerization mechanism during irradiation of the 5-alkyl substituted substrates in the presence of a base has been also substantiated.
ChemInform Abstract: Photoinduced Molecular Rearrangements. The Photochemistry of Some 1,2, 4-Oxadiazoles in the Presence of Nitrogen Nucleophiles. F…
2010
The photochemistry of some 3,5-disubstituted 1,2,4-oxadiazoles in the presence of nitrogen nucleophiles [external, such as added amines or hydrazines, or internal, such as an o-aminophenyl moiety at C(3) of the oxadiazole ring] has been investigated. In the irradiation of 5-amino-(or 5-N-substituted amino) 3-phenyl-1,2,4-oxadiazoles in the presence of aliphatic primary amines (or ammonia), photolytic species arising from heterolytic cleavage of the ring O−N bond capture the nucleophilic reagent to give open-chain intermediates, which develop into 1,2,4-triazolin-5-ones. Similarly, irradiations of 3,5-diphenyl-, 3-methoxy-5-phenyl-, and 5-methyl-3-phenyl-1,2,4-oxadiazoles gave 1,2,4-triazole…
Asymmetric synthesis and biological evaluation of 1,2,4-Oxadiazoles analogues of Linezolid
2014
Oxazolidinones are a class of antibacterial agents which displayed activity againist a variety of gram-positive pathogens and are highly potent against multidrug-resistant bacteria. Linezolid is the first oxazolidinone antibiotic approved for clinical use but linezolid resistance began to appear. 1,2,4 – Oxadiazoles are known bioactive heterocycles whose activity has been often associated to their bioisosterism with amide or ester functionalities [1]. As results of a research project on the molecular design of heterocycle – based antibacterials to contrast Multi-Drug Resistance (MDR) [2], we report the synthesis of 1,2,4 - Oxadiazole analogues of Linezolid. The synthesis has been achieved b…
FLUORINATED DERIVATIVES OF A POLYASPARTAMIDE BEARING POLYETHYLENE GLYCOL CHAINS AS OXYGEN CARRIERS
2008
Abstract In this paper the synthesis and characterization of new fluorinated polymers based on a polyaspartamide bearing polyethylene glycol (PEG) chains, are reported. The starting material was the α,β-poly(N-2-hydroxyethyl)- dl -aspartamide (PHEA), a water soluble and biocompatible polymer, that has been derivatized with both polyethylene glycol (with a molecular weight of 2000 Da) and 5-pentafluorophenyl-3-perfluoroheptyl-1,2,4-oxadiazole. By varying the amount of the fluorinated oxadiazole, three samples have been prepared and characterized by FT-IR, 1H NMR, 19F NMR and UV–VIS spectroscopy. Size exclusion chromatography analysis of these copolymers revealed the occurrence of a self-asso…
Translational readthrough of ciliopathy genes BBS2 and ALMS1 restores protein, ciliogenesis and function in patient fibroblasts
2021
Abstract Background Ciliary dysfunction underlies a range of genetic disorders collectively termed ciliopathies, for which there are no treatments available. Bardet-Biedl syndrome (BBS) is characterised by multisystemic involvement, including rod-cone dystrophy and renal abnormalities. Together with Alstrom syndrome (AS), they are known as the ‘obesity ciliopathies’ due to their common phenotype. Nonsense mutations are responsible for approximately 11% and 40% of BBS and AS cases, respectively. Translational readthrough inducing drugs (TRIDs) can restore full-length protein bypassing in-frame premature termination codons, and are a potential therapeutic approach for nonsense-mediated ciliop…
Heterocyclic photorearrangements. Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm
1988
Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm has been investigated. Ring photoisomerization to the 1,3,4-oxadiazole heterocycle or formation of open chain compounds involving the nucleophilic solvent was shown to depend on the nature and the position of the substituent. Photoinduced ring closure into the benzimidazole system, involving a 3-N-phenylamino side chain sequence and a photolytic intermediate of the oxadiazole heterocycle, is also reported.
ChemInform Abstract: Heterocyclic Photorearrangements. Photochemical Behaviour of Some 3,5-Disubstituted 1,2,4-Oxadiazoles in Methanol at 254 nm.
1989
Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm has been investigated. Ring photoisomerization to the 1,3,4-oxadiazole heterocycle or formation of open chain compounds involving the nucleophilic solvent was shown to depend on the nature and the position of the substituent. Photoinduced ring closure into the benzimidazole system, involving a 3-N-phenylamino side chain sequence and a photolytic intermediate of the oxadiazole heterocycle, is also reported.
Experimental and DFT studies on competitive heterocyclic rearrangements. part 2: A one-atom side-chain versus the classic three-atom side-chain (Boul…
2007
The experimental investigation of the base-catalyzed rearrangements of 3-acylamino-1,2,4-oxadiazoles evidenced a new reaction pathway which competes with the well-known ring-degenerate Boulton- Katritzky rearrangement (BKR). The new reaction consists of a one-atom side-chain rearrangement that is base-activated, occurs at a higher temperature than the BKR, and irreversibly leads to the corresponding 2-acylamino-1,3,4-oxadiazoles. An extensive DFT study is reported to elucidate the proposed reaction mechanism and to compare the three possible inherent routes: (i) the reversible three-atom side-chain ring-degenerate BKR, (ii) the ring contraction-ring expansion route (RCRE), and (iii) the one…
SYNTHESIS AND BIOLOGICAL EVALUATION OF NOVEL SMALL MOLECULES AS PROMISING ALTERNATIVE AGENTS TO COUNTERACT DRUG RESISTANCE IN CANCER AND MICROBIAL IN…
2022
Il cancro rimane un grave problema di salute pubblica, rappresentando la seconda principale causa di morte in tutto il mondo. Tra le diverse tipologie di tumori, l'adenocarcinoma duttale pancreatico (PDAC) è una delle forme più letali nell'uomo, a causa della diagnosi tardiva e delle limitate possibilità di trattamento. Pertanto, lo studio di nuove strategie terapeutiche per i pazienti affetti da PDAC è altamente necessario. Allo stesso modo, il mesotelioma rappresenta una malattia rara ma aggressiva, difficile da diagnosticare per il lungo periodo di latenza prima dei segni clinici. Gli approcci terapeutici standard includono la chirurgia, la chemioterapia e la radioterapia. Tuttavia, la s…