Luz Alegría

Synthesis and antiprotozoal activity of naphthofuranquinones and naphthothiophenequinones containing a fused thiazole ring

The synthesis of tetracyclic quinones 10a,b, 14a,b, 19a,b and 20a,b is described. The preparations involve regioselective Diels-Alder reactions via trapping the thiazole o-quinodimethane 9 with several benzofuranquinones and benzothiophenequinones. The structure of the regioisomers was assigned through 2D NMR 1H-13C HMBC experiments performed on 10a and 14a. Compounds 10a,b, 14a as well as phenol 1 and the starting quinones 2, 5, 7 and 15 are evaluated against Leishmania sp., Toxoplasma gondii and THP-1 cells. Almost all the tested compounds exhibit significant antiprotozoal activities with lower cytotoxicities than the reference compounds. Among them, quinones 2 and 14a possess the best activities towards L. donovani and T. gondii with the lowest toxicities.

A Diels–Alder strategy towards a benzonaphthopyranoquinone

Abstract Reaction of a suitably protected aryllithium derivative with citral, and subsequent deprotection and cyclization was used to obtain dibenzopyran 5 , a precursor of the tricyclic quinone 6 . Diels–Alder reaction of 6 with 1,3-dimethoxy-1-trimethylsilyloxy-1,3-butadiene 7 led to benzonaphthopyranoquinone 8 . The regioselectivity in the dienophilic partner is governed by the remote oxygen of the pyran ring.

Interfacial Properties of Poly(N‐Vinyl‐2‐Pyrrolidone) at the Air/Water Interface

Abstract Spread films of poly(N‐vinyl‐2‐pyrrolidone) (PVP) were studied at the air/water interface by using the Langmuir technique. Influence of the subphases of different thermodynamic conditions were analyzed. Surface pressure–area (π–A) isotherms change sensitively with the temperature. Adsorption layers (Gibbs surface excess layer) of aqueous solutions of PVP were also investigated using the interfacial tension measurements. The influence of the PVP concentration and temperature on the adsorption behavior of PVP solutions was determined. The behavior of spread films is contrasted to the behavior of surface excess layers for this polymer. The driving force for adsorption of PVP at the air/aqueous interface seems to arise from an entropic contribution. It was observed that when the polymers hydrodynamic volume decreases (0.55 M Na2SO4, θ‐solvent), a more favorable entropy adsorption was obtained. Comparison of the spread film and surface excess layer data seems to indicate that the interfacial segment density is lower in the surface excess layer than in the spread film.

Hetero-Diels–Alder reaction of halogenated quinones with a polygodial-derived azadiene

The reaction between polygodial dimethylhydrazone and haloquinones under an air atmosphere is described. The terpene moiety undergoes a degradative oxidation to an 11-norsequiterpene ketone containing a quinolinequinone skeleton.

Copolymers of Phenoxyethyl Methacrylate with Butyl Methacrylate: Synthesis, Characterization and Reactivity Ratios

Phenoxyethyl methacrylate (POEMA) and butyl methacrylate (BMA) were copolymerized by free-radical copolymerization using α,α′-azobisisobutyronitrile (AIBN) in 2-butanone solution at 333±1 K. Copolymers were characterized by FTIR, 1H-NMR and 13C-NMR spectroscopic methods and by comparison of the spectra with the corresponding homopolymers. Thermogravimetric analysis of the copolymers was carried out in order to know their thermal stability. Copolymer composition was established by 1H-NMR analysis. Monomer reactivity ratios (MRR) were computed using the classical Fineman – Ross (FR) and Kelen – Tüdos (KT) procedures. MRR were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The mean sequence lengths of the copolymers were estimated and suggest that random copolymers were obtained.

Blends Containing Amphiphilic Polymers VI. Compatibilization of N-alkylitaconamic acid-co-Styrene Copolymers with Poly(hydroxypropyl methacrylate) and Poly(4-vinylphenol)

Blends containing copolymers of N-alkylitaconamic acid (NAIA) with styrene (NAIA-co-S) of two copolymer compositions, that is, 80% and 50% styrene, with poly(hydoxypropyl methacrylate (PHPM) and poly(vinyl phenol) (PVPh) were studied by differential scanning calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FT-IR). The phase diagrams of Tg against blend composition show one single Tg value, which are intermediate to those of the pure components. This is interpreted as miscibility over the whole range of compositions in both systems. The Calorimetric Analysis using Gordon Taylor, Couchman, and Kwei treatments allows one to conclude that interactions between the components is favorable to the miscibility. FT-IR spectra show important displacements in the wavenumber corresponding to the carbonyl groups of the itaconamic acid moiety. This behavior is atributed to strong interaction by hydrogen bonds formation, taking into account that PHPM and PVPh are interacting polymers. FTIR analysis of the blends suggests that the driving force for miscibility is hydrogen bonds formation. The variation of the absorptions of the carbonyl groups of PNAIA and the hydroxyl groups of P4VPh allows to attribute the miscibility to weak acid-base like interactions.

SYNTHESIS OF 3,4,4a,12b-TETRAHYDRO-2,5,5-TRIMETHYL-2H-BENZO[b]- NAPHTHO[2,3-b]PYRAN-7,1 2-DIONΕ

Naturally occurring naphtho[2,3-b]piranoquinones are a growing class of compounds known for their antimicrobial and antitumor activity.(1) As part of a screening for antioxidants, the tetracyclic naphthopiranoquinones naphterpin 1 and 7-demethylnaphterpin 2. have been isolated from S. aeriouvifer and S. violaceus respectively. (2,3) These metabolites inhibited lipid peroxidation in rat liver microsomes with IC 5 0 values comparable to that of vitamin E.

Comparative Study of Thermal Degradation of N-vinylimidazole/Phenoxy- and Methoxyethylmethacrylate Copolymers

Copolymerization reactions involving N-vinylimidazole and its derivatives have stimulated great interest due to the wide possibilities of the preparation of new materials, including the synthetic analogues of biopolymers with imidazole fragments. The role of the imidazole group in polymers is very important, especially due to the high thermal stability at elevated temperatures when it is copolymerized with methacrylates, which contain highly electronegative atoms like oxygen [10,11]. Accordingly, copolymers of N-vinylimidazole with phenoxy- and methoxyethylmethacrylate have been prepared and subjected to thermogravimetric analysis to discover their thermal stability. Copolymers are also characterized by FTIR and 1H-NMR spectroscopic methods. Results show that the thermal stability is greater for N-vinylimidazole-co-phenoxyethylmethacrylate than for those with N-vinylimidazole-methoxyethylmethacrylate.

Non-steroidal anti-inflamatory drugs as guest of dendronized polymeric nanocomposites

The study of dendronized polymeric nanocomposites like poly(diethylaminoethyl methacrylamide) (PEAM), poly(acryloil tris nitrile/(methylester)) (PATCN) and dendronized poly(e-caprolactone) as carriers of different non- steroidal antiinflamatory drugs like ibuprofen (IBU), ketoprofen (KTP), naproxen (NPX) and indomethacin (IMTh) are reported.

Polymers containing phtalimidoalkyl groups in the side chains. effect of the alkyl groups in monolayers at the airwater interface

Abstract Surface activity of poly(methacrylate)s containing phthalimidoalkyl groups was studied. Surface pressure-area isotherms ( -A) at the air-water interface were determined. These polymers form stable and condensed monolayers. The monolayers are more condensed and the limiting surface area A0 values decrease when the number of the methylene groups in the lateral chains increases. Surface pressure variation at the semidilute region of the monolayers was expressed in terms of the scaling laws as power function of the surface concentration. The static elasticity εo and the exponent of the excluded volume υ were determined. The hydrophobicity degree of polymers was estimated from the determination of the total surface free energy values by wettability measurements. Molecular dynamic simulation (MDS) was performed in order to explain the experimental behavior of polymers at the air-water interface.