Search results for "Moiety"
showing 10 items of 621 documents
On the Use of Metal Purine Derivatives (M=Ir, Rh) for the Selective Labeling of Nucleosides and Nucleotides
2014
The reactions of neutral or cationic IrIII and RhIII derivatives of phenyl purine nucleobases with unsymmetrical alkynes produce new metallacycles in a predictable manner, which allows for the incorporation of either photoactive (anthracene or pyrene) or electroactive (ferrocene) labels in the nucleotide or nucleoside moiety. The reported methodology (metalation of the purine derivative and subsequent marker insertion) could be used for the postfunctionalization and unambiguous labeling of oligonucleotides.
A theoretical study of the low-lying excited states of thieno[3,4-b]pyrazine
2009
The low-lying electronic excited states of thieno[3,4-b]pyrazine have been studied using the multiconfigurational second-order perturbation CASPT2 theory with extended atomic natural orbital basis sets. The CASPT2 results allow for a full interpretation of the electronic absorption and emission spectra and provide valuable information for the rationalization of the experimental data. The nature, position, and intensity of the spectral bands have been analyzed in detail. A preliminary comparative study of the ground-state geometry of thieno[3,4-b]pyrazine has been performed at the coupled cluster single and doubles and density functional theory levels using a variety of correlation-consisten…
Conformational and Tautomeric Control by Supramolecular Approach in Ureido-N-iso-propyl,N’-4-(3-pyridin-2-one)pyrimidine
2019
Ureido-N-iso-propyl,N&rsquo
Pyrrolo[3,4-h]quinolinones a new class of photochemotherapeutic agents
2011
Abstract Pyrrolo[3,4- h ]quinolin-2-ones were synthesized as nitrogen isosters of the angular furocoumarin angelicin, with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects. A versatile synthetic pathway was approached to allow the isolation of derivatives of the new ring system with a good substitution pattern on the pyrrole moiety. Photobiological screenings of the new compounds revealed a potent phototoxic effect and a great UVA dose dependence, reaching IC 50 values at submicromolar level. The induced cellular photocytotoxicity was related to apoptosis with the involvement of mitochondria and lysosomes, alte…
Aza-isoindolo and isoindolo-azaquinoxaline derivatives with antiproliferative activity
2015
Abstract Three new ring systems, pyrido[2′,3′:3,4]pyrrolo[1,2- a ]quinoxalines, pyrido[3′,2′:3,4]pyrrolo[1,2- a ]quinoxalines and pyrido[2′,3′:5,6]pyrazino[2,1- a ]isoindoles, were synthesized through an aza-substitution on the already active isoindolo-quinoxaline system and in particular in the position 7 or 4 of the isoindole moiety and in position 5 of the quinoxaline portion. All new compounds were screened by the National Cancer Institute (Bethesda, MD) against a panel of 60 human tumor cell lines. Biological results of the most active derivatives, with pGI 50 values between 7.09 and 7.27, confirmed the importance of the presence of methoxy substituents for biological activity. The ant…
Photochemistry of Fluorinated Heterocyclic Compounds. An Expedient Route for the Synthesis of Fluorinated 1,3,4-Oxadiazoles and 1,2,4-Triazoles
2004
The photochemistry of some 3-N-alkylamino-5-perfluoroalkyl-1,2,4-oxadiazoles in the presence of nitrogen nucleophiles such as ammonia and primary and secondary aliphatic amines has been investigated. The primary photolytic intermediate from the cleavage of the ring O-N bond follows two distinct and competing pathways leading to (i). 5-perfluoroalkyl-1,3,4-oxadiazoles, through the ring contraction-ring expansion photoisomerization route favored by the presence of the base or (ii). 5-perfluoroalkyl-1,2,4-triazoles, through the intervention, as an internal nucleophile, of the exocyclic N-alkylamino moiety of the oxadiazole followed by the attack of the external nitrogen nucleophile and subsequ…
Anthelminthische Wirkstoffe, 5. Mitt.: Langkettig und hydroheterocyclisch substituierte Chlor-diallylamino-1,3,5-triazine
1988
Aus der Umsetzung von 2,4-Dichlor-6-(diallylamino)-1,3,5-triazin (1) mit den aliphatischen Aminen 2a–c gehen die langkettig substituierten Chlordiallylamino-1,3,5-triazine 3a–c, mit den Piperazinen 4a–c die hydroheterocyclisch substituierten Chlor-diallylamino-1,3,5-triazine 5a–c, hervor. Unter den zur Strukturcharakterisierung herangezogenen spektroskopischen Daten ist besonders in den Massenspektren des Strukturtyps 5 die Abspaltung des Neutralteilchens Phenyl-NH2 unter Ausbildung des Radikalkations bei m/z 277 auffallig. 3 und 5 zeichnen sich durch anthelminthische, trichomonazide, insektenwachstumsregulatorische und fiebersenkende Wirkungen aus. Anthelminthic Agents, V: Chloro(diallylam…
ChemInform Abstract: 3,4-Dihydro-2H-pyrrole-2-carbonitriles: Useful Intermediates in the Synthesis of Fused Pyrroles and 2,2′-Bipyrroles.
2016
Various heterocyclic structures containing the pyrrole moiety have been synthesized from easily accessible 3,4-dihydro-2H-pyrrole-2-carbonitriles in one-pot procedures. 5,6,7,8-Tetrahydroindolizines, 2,3-dihydro-1H-pyrrolizines as well as 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines were obtained from these precursors in high yields in an alkylation/annulation sequence. The same conditions were applied in the synthesis of a 5,8-dihydroindolizine, which could easily be transformed to the corresponding indolizine by dehydrogenation. Furthermore, oxidative couplings of 3,4-dihydro-2H-pyrrole-2-carbonitriles with copper(II)-salts furnished 2,2′-bipyrroles as well as 5,5′-bis(5-cyano-1-pyrroline…
Efficient Synthesis of 5-Chalcogenyl-1,3-oxazin-2-ones by Chalcogen-Mediated Yne-Carbamate Cyclisation: An Experimental and Theoretical Study
2014
A very efficient synthesis of 5-chalcogenyl-1,3-oxazin-2-ones has been accomplished by the chalcogen-mediated yne–carbamate cyclisation of chiral, non-racemic N-Cbz-protected propargylic amines using PhXY (X = Se, S, Te; Y = Br or Cl) as electrophile sources. The reactions gave good-to-excellent yields for a wide range of substrates. In all cases the reaction was totally regioselective, occurring by a 6-endo-dig process regardless of the nature of the reagent and of the substituents in the starting material. This methodology permits the formation of the 1,3-oxazin-2-one moiety as well as the simultaneous installation of a chalcogen functionality onto the heterocyclic ring. The experimental …
Reaction mechanism of regioisomerization in binuclear (diaminocarbene)PdII complexes
2021
Abstract A series of binuclear PdII carbene complexes were synthesized via the treatment of cis-[PdCl2(CNXyl)2] (1) with benzo-1,3-thiazol-2-amines (2–6) and structurally characterized. In every case the reaction leads to the mixture of two regioisomers, which are able to interconvert. The study of the regioisomerization of the binuclear diaminocarbene species showed that it is a first-order reaction, that is, it occurs intramolecularly, and was analyzed with the Hammett function. Electron-withdrawing substituents in the benzothiazole moiety of the complexes as well as increasing the solvent polarity accelerate the reaction. The solvent donor strength correlates less well with the isomeriza…