Lúcia Helena Brito Baptistella

An improved synthesis of 2,3- and 3,4-unsaturated pyranosides: The use of microwave energy

Tipson-Cohen reactions of sugar derivatives containing contiguous sulfonyloxy groups have been studied in a microwave oven. Considerable rate increases and high yields of the unsaturated products have been observed.

Synthesis of benzyl and methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β-l-galactopyranoside: Protected C-2 fluoro analogues of daunosamine

Abstract The reaction of benzyl 2-benzamido-4,6- O -benzylidene-2-deoxy-3- O -tosyl-α- d -glucopyranoside or benzyl 4,6- O -benzylidene-2,3-benzoylepimino-2,3-dideoxy-α- d -allopyranoside with anhydrous tetrabutylammonium fluoride in hexamethylphosphoric triamide gave ∼40% of benzyl 3-benzamido-4,6- O -benzylidene-2,3-dideoxy-2-fluoro-α- d -altropyranoside ( 6a ). Transformation of 6a into benzyl 3-benzamido-2,3,6-trideoxy-2-fluoro-α- d - arabino -hex-5-enopyranoside ( 13a ) was carried out by well-established methodology. Hydrogenation of the double bond in 13a furnished the title compound in good yield. Methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β- l -galactopyranoside was also prepared in nine steps from 2-amino-2-deoxy- d -glucose.

CHROMIUM (VI) ADSORBED ON SIO2/ZRO2, A NEW SUPPORTED REAGENT FOR ALLYLIC OXIDATIONS

Abstract Zirconium (IV) oxide coated on the surface of silica gel was used to absorb Cr(VI) from acidic solutions. This material, in conjunction with t-butyl hydroperoxide, proved to be very useful for allylic oxidations, promoting very clean reactions, with high regioselectivity.

Ácidos siálicos: da compreensão do seu envolvimento em processos biológicos ao desenvolvimento de fármacos contra o agente etiológico da gripe

Sialic acids are nine-carbon carbohydrates that occur widely in nature and occupy the terminal portions of some glycoproteins and glycolipids of cell membranes. These carbohydrates are closely involved in cell-cell interactions and in processes such as microbial infection, inflammation, etc. Studies on the participation of sialic acids in biological processes have provided comprehension about their role in the infection by the influenza virus, the causal agent of flu. In this article, we present an overview of the importance of sialic acids in the influenza virus infection and how the knowledge of their involvement in this process has allowed the development of selective and efficient drugs against the virus.

Preparação do (+)-±-terpineol a partir do (+)-limoneno: monoterpenos de odor agradável em um projeto para química orgânica experimental

A synthesis of (+)-±-terpineol from (+)-limonene was proposed as a project for undergraduate organic laboratory course. Terpineol is a useful flavor and fragrance compound, and several aspects of this preparation are suited for experimental organic classes, including basic techniques for extraction and analyses of essential oils, different reaction types and the possibility of a high degree of student interest.

Absolute configuration of some dinorlabdanes from the copaiba oil

A novel ent-dinorlabdane (-)-13(R)-14,15-dinorlabd-8(17)-ene-3,13-diol was isolated from commercial copaiba oil along with two known dinorlabdanes. The absolute configuration of these dinorditerpenes was established for the first time through synthesis starting from known (-)-3-hydroxycopalic acid, which was also isolated from the same oleoresin.

α'-Hydroxy-α, β-unsaturated tosylhydrazones: Preparation and use as intermediates for carbonyl and enone transpositions

ABSTRACT Regiospecifically generated α,β-unsaturated tosylhydrazones dianions are treated with molecular oxygen, yielding α′-hydroxy-α,β-unsaturated tosylhydrazones, versatile intermediates for organic synthesis. They proved to be useful for 1,2-carbonyl and 1,2-enone transpositions, and also permitted the preparation of α′-hydroxy enones in very high yields.

13C and 1H NMR signal assignments of some new synthetic dehydroabietic acid derivatives.

The 1H and 13C NMR signal assignments of a series of new synthetic derivatives of dehydroabietic acid are presented. Copyright

Nitração do fenol, um método em escala semi-micro para disciplina prática de 4 horas

A procedure for the nitration of phenol in a semi-micro scale, followed by separation of the formed orto- and para-nitrophenol isomers by column chromatography, is described. All the experiment, including determination of the melting point of the isolated products, require a period of 4 hours, and it is suitable for organic chemistry laboratory undergraduate courses.

Resolução do ibuprofeno: um projeto para disciplina de química orgânica experimental

A practical and didactic sequence of experiments was proposed to illustrate the stereochemistry concept, optically active compounds, resolution of racemates, and use of the NMR technique, including 2D-COSY for identification of organic compounds, on a laboratory course for undergraduate students. The sequence was: extractions of racemic ibuprofen and chiral naproxen from commercial tablets; syntheses of diastereoisomeric amides reacting chiral (S)-(-)-α-methylbenzylamine with (±)-ibuprofen; separation and determination of absolute configuration of amides by 1H NMR spectroscopy and GC analysis, and hydrolysis of amides to obtain (+)- and (-)-ibuprofen.