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  • Open access
  • 43 Reads
Synthesis of a tricationic subphthalocyanine with potential use in photoinactivation of bacteria
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A novel chloro[2,9,16(2,9,17)-trikis-4-(N-methylpyridyloxy)]subphthalocyaninnato boron(III) iodide (SubOPc3+) has been synthesized by boron trichloride-induced cyclotrimerization of 4-(4-pyridyloxy)phthalonitrile in 1-chloronaphthalene. This approach produced a regioisomers mixture of chloro[2,9,16(2,9,17)-trikis-4-(pyridyloxy)]subphthalocyaninnato boron(III) (SubOPc) with 19% yield. Exhaustive methylation of SubOPc with methyl iodide yielded 92% of tricationic SubOPc3+. The spectroscopic and photodynamic properties of the SubOPc3+ were compared with its homologous non-charged SubOPc and with subphthalocyanine (SubPc). The cationic SubOPc3+ is essentially aggregated in solution of different solvents and it is partially dissolved as monomer in N,N-dimethylformamide (DMF)/water (10% v/v)/HCl (1.2 mM). The singlet molecular oxygen, O2(1Δg), production was evaluated using 9,10-dimethylanthracene (DMA). The photodynamic effect was strongly dependent of the medium, diminishing where the sensitizer is aggregated but it increases in an appropriated surrounding microenvironment. The studies show that SubOPc3+ can be an interesting agent with potential applications in photodynamic inactivation of bacteria.
  • Open access
  • 55 Reads
Heterocyclization Reactions of 4-Hydrazinoquinazoline with Dicarboxylic Acid Anhydrides
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An interaction of 4-hydrazinoquinazoline with dicarboxylic acid anhydrides is investigated. Carrying out the reaction in mild conditions proper hydrazidoacids were synthesized. The reaction in the glacial acetic acid medium is accompanied with the cascade of tandem transformations because of dehydration of an above intermediate hydrazidoacids. Instead, the reaction of campharic, endic, phthalic anhydrides and its hydrogenated analogues with rigid framework carcass, results in the formation of proper imidoaminic structures. An interaction of 4-hydrazinoquinazoline with a succinic and glutaric acid anhydrides, and also the heterocyclization of monoethyl ether of oxalic acid 2-(4(3H)-quinazolinyliden)hydrazide is accompanied with the formation of 2-R-[1,2,4]triazolo[1,5-c]quinazolines via Dimroth-like rearrangement of the expected [4,3-c] series.
  • Open access
  • 36 Reads
The Preparation of 7-Substituted Norbornadiene-2,3-dicarboxylic Anhydrides and a Theoretical and Experimental Study of their Thermolysis to 5-Membered Carbocyclic or Heterocyclic Anhydrides
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New substituted methano-bridged or heteroatom-bridged norbornadienomaleic anhydrides have been prepared and converted to sesquinorbornadiene anhydrides by reaction with cyclic 1,3-dienes. The versatility of parity reversal, in conjuction with N-substituent steric effects, has been used to produce stereoisomers of the N,O-sesquinorbornadiene anhydrides in separate, stereoselective cycloadditions. The anhydrides have been synthesized by cyclisation of their diacids (in situ production) or by flash vacuum pyrolysis of their furan adducts (yielding crystalline products); further fragmentation occurs at these or higher temperatures to produce five-membered carbocyclic or heterocyclic anhydrides. Activation energies have been evaluated for the two fragmentation processes and Diels-Alder reactions using DFT calculations (B3LYP/6-31G*) and these calculations correctly predict which reactions can be intercepted at the norbornadienomaleic anhydride stage.
  • Open access
  • 62 Reads
Synthesis of Novel Coumarin Based Fluorescent Probes
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We report on synthesis of new fluorescent probes suitable for site specific incorporation into oligonucleotides. Coumarin derivatives (1-5) were used as sensitive fluorescent labels and two linkers (6-7) were attached to the basic coumarin skeleton for further applications. Spectral characteristic of functionalized coumarin derivatives (8-10,13-14) were measured and derivative with the best fluorescent properties was chosen. Phosporamidite derivative 17 was prepared from functionalized coumarin derivative 9.
  • Open access
  • 61 Reads
Chemoselective lithiation of 6-chloro-1-halohex-1-ynes with lithium/naphthalene
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The reaction of different 6-chloro-1-halohex-1-ynes (1) with lithium naphthalene (1:2 molar ratio) and a carbonyl compound R1R2CO in THF at –78°C leads, after hydrolysis with water, to the corresponding chlorinated alcohols 2 through a selective lithiation of the sp carbon-halogen bond. The DTBB-catalysed lithiation of 6-chloro-1-halohexynes (1) in the presence of an excess of a carbonyl compound R1R2YCO as electrophile in THF at -78 ºC led, after hydrolysis with water, to diols 3.
  • Open access
  • 108 Reads
Synthesis and Photochemistry of 1-iodocyclohexene: Influence of Ultrasound on Ionic vs. Radical Behaviour
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Simultaneous application of UV light and ultrasonic irradiation on the reaction mixture of 1- iodocyclohexene is reported. The irradiation of 1-iodocyclohexene was carried out in the with or without of zinc. The effect of ultrasound and mechanical stirring on solid-liquid system was compared.
  • Open access
  • 58 Reads
Dimeric Anhydro Bases from Benzothiazole Derivatives
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In order to develop a novel strategy for the synthesis of aminothiol derivatives, the cycloadducts obtained from the reaction of 4-alkenylthiazoles with N-substituted maleimides and similar products where the central ring is totally oxidized, were used as starting materials in the sequence N-methylation, reduction and hydrolytic cleavage of the thiazole ring. However, instead of the expected aminothiol derivative, a dimeric anhydro base was isolated in the last step. The mechanism implies the formation of a thiazolium cation which evolves to the dimeric anhydro base under the basic conditions.
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