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Six-membered ring systems: with O and/or S atoms
Santos, Clementina M. M.; Silva, Artur M.S.A large variety of publications have emerged in 2012 involving O- and S-6- membered ring systems. The increasing number of reviews and other communica- tions dedicated to natural and synthetic derivatives and their biological significance highlights the importance of these heterocycles. Reviews on natural products involve biosynthesis and isolation of enantiomeric derivatives h12AGE4802i, biosynthesis, isolatio...
Electrochemical characterization of bioactive hydroxyxanthones by cyclic voltam...
Santos, Clementina M.M.; Garcia, Beatriz; Silva, Artur; Santus, René; Morlière, Patrice; Fernandes, EduardaThe present study reports the electrochemical behavior of several phenolic and catecholic-substituted 2,3-diarylxanthones on a glassy carbon electrode, challenged by cyclic voltammetry at different pH values (4.0, 7.4, and 11.0). Higher pH values required lower anodic and cathodic peak voltages. The oxidation of catecholic groups occurred at lower peak potentials in a reversible and pH dependent manner. Anodic ...
Synthesis of 2-{2-[5(4)-aryl-2H-[1,2,3]-triazol-4(5)-yl]vinyl}chromen-4-ones
Albuquerque, Hélio; Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José A.S.Chromones are a family of oxygen-containing heterocyclic compounds that have been shown particular relevant biological activity. In what concerns to 2-methylchromones, their reactivity is well-known and allowed to exploit many different kinds of chemical reactions. The acidic character of the 2-methyl group, due to the low electron density at C-2 caused by carbonyl group enable this class of compounds to underg...
Synthesis of (E)-2-(4-Arylbut-1-en-3-ynyl)-4H-chromen-4-ones
Albuquerque, Hélio; Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José A.S.Chromones are a well-known class of naturally occurring oxygen-containing heterocyclic compounds; many of them playing important biological functions in nature.[IJ Although 2- methylchromones are one of the scarcest classes of natural chromones, their synthesis and reactivity is well studied. They can participate in several chemical transformations such as oxidation, thiation, hydrogenation, photolysis, cycload...
The response of rapeseed cultivar hydromel to nitrogen fertilization: chemical ...
Costa, Dina; Santos, Clementina M.M.; Silva, Artur; Rodrigues, M.A.Winter rapeseed (Brassicanapus L.) is a species of the Brassicaceae family and an important agricultural crop in many cold temperate countries, where most of other plants do not grow. It is mainly cultivated in Europe, Asia, North America and Australia, but has a limited acreage in Portugal. The growing demand from rapeseed is dueto a progressive increase in its quality for human and animal consumption and main...
Synthesis of (E)-2-(4-Arylbut-1-en-3-ynyl)-4H-chromen-4-ones
Albuquerque, Hélio; Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José A.S.Chromones are a well-known class of naturally occurring oxygencontaining heterocyclic compounds; many of them playing important biological functions in nature [1]. Although 2-methylchromones are one of the scarcest classes of natural chromones, their synthesis and reactivity is well studied. They can participate in several chemical transformations such as oxidation, thiation, hydrogenation, photolysis, cycloadd...
Synthesis of 2-{2-[5(4)-aryl-2H-[1,2,3]-triazol-4(5)-yl]vinyl}chromen-4-ones
Albuquerque, Hélio; Santos, Clementina M.M.; Silva, Artur; Cavaleiro, José A.S.Chromones are a family of oxygen-containing heterocyclic compounds that have been shown particular relevant biological activity. In what concerns to 2-methylchromones, their reactivity is well-known and allowed to exploit many different kinds of chemical reactions. The acidic character of the 2-methyl group, due to the low electron density at C-2 caused by carbonyl group enable this class of compounds to underg...
The response of rapeseed cultivar hydromel to nitrogen fertilization: chemical ...
Costa, Dina; Santos, Clementina M.M.; Silva, Artur; Rodrigues, M.A.Winter rapeseed (Brassicanapus L.) is a species of the Brassicaceae family and an important agricultural crop in many cold temperate countries, where most of other plants do not grow. It is mainly cultivated in Europe, Asia, North America and Australia, but has a limited acreage in Portugal. The growing demand from rapeseed is dueto a progressive increase in its quality for human and animal consumption and main...
Efeito da adubação azotada na composição química de sementes de colza da cultiv...
Costa, Dina Raquel Luís da; Santos, Clementina M.M.; Silva, Artur; Rodrigues, M.A.Neste trabalho pretendeu-se avaliar o efeito da adubação azotada na composição química de sementes de colza da cultivar Hydromel. As amostras de semente de colza foram obtidas num ensaio de campo que decorreu em Bragança, em que a colza foi cultivada em ciclo de outono/inverno, na estação de crescimento de 2009/2010. No que diz respeito à composição química determinou-se o teor em humidade, cinzas, proteína, go...
Six-membered ring systems: with O and/or S atoms
Santos, Clementina M.M.; Silva, ArturThe year 2011 was particularly rich in reviews involving the synthesis and transformations of a wide structural range of 0- and S-6-membered heterocycles and some on their biological properties, reflecting their importance for the scientific conmmnity. An overview on the structure and biological activity of naturally occurring withanolides < 11 NPR 705> and a review on structure, biological activity, and synthe...
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