Browsing by Author "Valderrama, C"

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    Studies on quinones .30. Synthesis of benzo[b]thiophene-4,7-quinones
    (1997) Valderrama, JA; Valderrama, C
    The synthesis of a variety of benzo[b]thiophene-4,7-quinones (4a-f) by oxidative demethylation of the corresponding 4,7-dimethoxybenzo[b] thiophenes (3a-f) with cerium(IV) ammonium nitrate is reported. Heterocycles (3a,b) were prepared by cyclization of the corresponding 2,5-dimethoxy-6-nitrobenzaldehyde (1a) and 2,5-dimethoxy-6-nitroacetophenone (1b) with methyl thioglycolate.
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    Studies on quinones. Part 32. Regioselective synthesis of benz[b]phenantridines related to phenantroviridone
    (PERGAMON-ELSEVIER SCIENCE LTD, 1999) Valderrama, JA; Gonzalez, MF; Valderrama, C
    The Diels-Alder reaction of juglone (4) and bromojuglone 18 with 1-cyclohesenecarbosaldehyde dimethylhydrazone (3) is described. Through these cycloaddition reactions 8-hydroxy-1,2,3,4-tetrahydrobenz[b]phenantridin-7,12-dione (5) was obtained in 55 and 78% yield, respectively. Oxidation of 5 to 8-hydroxybenz[b]phenantridin-7,12-dione (6) and 8-hydroxy-1,2,3,4-tetrahydrobenz[b]phenantridin-1,7,12-trione (15) is also reported. (C) 1999 Elsevier Science Ltd. All rights reserved.
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    Synthesis and in vitro antiprotozoal activity of thiophene ring-containing quinones
    (PHARMACEUTICAL SOC JAPAN, 1999) Valderrama, J; Fournet, A; Valderrama, C; Bastias, S; Astudillo, C; de Arias, AR; Inchausti, A; Yaluff, G
    A series of quinones (3a-i, 4-9, 11) and aromatic compounds (2a, 2d, 2g) containing the thiophene ring were tested in vitro against the trypomastigote form of Trypanosoma cruzi and the promastigote forms of Leishmania. The quinones 3a-i, 4, 5a, b, 6 and 9 having the thiophene ring fused to a quinone nucleus were the most active members of the series. The electron affinities of the benzo[b]thiophene-4,7-quinones 3, evaluated by their LUMO energies and halfwave potentials, are reported.