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  • Open access
  • 45 Reads
Synthesis and photophysical characterisation of long alkyl side-chain derivatives of benzo[a]phenoxazinium salts
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Several fluorescent benzo[a]phenoxazinium chlorides possessing a long hydrocarbon chain terminated with methyl, hydroxyl, carboxylic acid or ester groups as substituent at the 5-amino function of the heterocycle were efficiently synthesised. Studies of their photophysical properties revealed that all compounds absorbed and emitted at longer wavelengths with moderate to good fluorescent quantum yields.
  • Open access
  • 32 Reads
Highly Regioselective Synthesis of Functionalized Aminonitriles Starting from 2-(w-cyanoalkyl)aziridines
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1-arylmethyl-2-(bromomethyl)aziridines were transformed into the corresponding 2-(cyanomethyl)aziridines and 2-(2-cyanoethyl)aziridines upon treatment with potassium cyanide in DMSO and a-lithiated trimethylsilylacetonitrile in THF, respectively. Further elaboration of 1-arylmethyl-2-(cyanomethyl)aziridines afforded 4-amino-2-butenenitriles, 3,4-diaminobutanenitriles and 2-aminocyclopropanecarbonitriles. Additionally, 1-arylmethyl-2-(2-cyanoethyl)aziridines were efficiently converted into biologically relevant 2-(aminomethyl)-cyclopropanecarbonitriles.
  • Open access
  • 40 Reads
Hydroamination of alkynes as a new source of Imines for Ugi MCRs - Scope and Limitations
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The hydroamination of alkynes has been implemented to form imines which are involved in Ugi multicomponent reactions. The catalytic hydroamination (using Zn(OTf)2, clays and Au catalysts) of anilines with terminal alkynes has furnished the corresponding imines with useful yields and these intermediates have been reacted in a tandem manner with isocyanides and carboxylic acids to yield the Ugi adducts. Although synthetically useful, as the process enables the use of alkynes as inputs in Ugi reactions, the main limitation deals with the low overall yields and the incompatibility of isocyanides with the metal catalysts which prevents the direct interaction of all four components. However, a one-pot process, separating both reactions, is feasible.
  • Open access
  • 41 Reads
Dependence of Spectral Parameters in 1H and 13C NMR Spectra of Aromatic Compounds Upon Substituent Spatial-Structural Peculiarities
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The presence of opposite by ßOH shifts of ortho-protons (downfield, if the substitution takes place in ?-position and upper-field – in ?-position) by the substitution of hydrogen atoms for methyl groups in alkyl chain of alkylbenzenes has been found. The independent influence of both effects at the simultaneous branching near ?- and ?-hydrocarbon atoms of alkyl chain has been determined. The mentioned phenomena has been explained by conformational peculiarities of alkylbenzenes structure.
  • Open access
  • 58 Reads
Phosphoric ligands immobilized on polymeric resins
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Hydrogen cyanide (HCN) addition is chemical reaction taking important part in chemical industry over the world. HCN addition reactions are one the most used synthetic routes leading to cyano compounds which are indispensable materials for pharmaceutical industry and chemical industry itself as well. The key role in HCN additions is represented by the catalytic system present in reaction mixtures, which increases yields and purity of desired product and decreases energetic and material demands of the reaction at the same time. It is known that Ni(0)-complexes stand as the most used catalysts in such mixtures having high efficiency and selectivity, although catalytic system may be rather complicated and the resulting product can be dependent on many factors. Some disadvantages of such homogenous catalytic systems could be eliminated using immobilized Ni-complexes as catalysts. First step in this approach is to prepare phosphoric ligands immobilized on suitable polymeric resin.
  • Open access
  • 51 Reads
Synthesis and Antiviral Activities of Novel Purinyl- and Pyrimidinylcarbanucleosides Derived from Indan
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Starting from (±)-trans- and (±)-cis-3-hydroxymethyl-1-indanol, novel 6-substituted purinylcarbanucleoside derivatives of indan (5, 6, 9, 10, 15 and 17) were synthesized through a key coupling reaction with 6-chloropurine under Mitsunobu conditions. Suzuki–Miyaura reactions of the protected 6-chloropurine derivative with different arylboronic acids afforded the corresponding 6-arylpurinylcarbanucleoside derivatives. Finally, three new 5-halouracilcarbanucleosides (19, 20 and 21) were prepared by reaction of uracilcarbanucleoside 18 with different N-halosuccinimides. All of the new analogues were evaluated for antiviral activity against a wide variety of viruses.
  • Open access
  • 59 Reads
A convenient synthesis of new 6-substituted purinylcarbanucleosides on cyclopenta[b]thiophene
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The first members of a new family of heterocarbobicyclic nucleoside analogues have been synthesized from the cis/trans mixture of (4-amino-5,6-dihydro-4H-cyclopenta[b]thiophen-6-yl)methanols cis/trans-7. The separation of cis and trans intermediates during preparation of the 6-chloropurine derivatives allowed separate preparation of the purine heterocarbanucleosides cis-10 and trans-11, from which cis-(12-14) and trans-(16-18) were obtained by replacement of the 6-chloro substituent with amino, hydroxy and cyclopropylamino groups. Additionally, the 6-phenyl-purinyl analogues cis-15 and trans-19 were prepared from cis-10 and trans-11 using Suzuki-Miyaura methodology.
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