Browsing by Author "ARAYA-MATURANA, R"

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    STUDIES ON QUINONES .21. REGIOSELECTIVE SYNTHESIS OF TETRACYCLIC QUINONES RELATED TO RABELOMYCIN
    (1991) VALDERRAMA, JA; ARAYA-MATURANA, R; GONZALEZ, MF; TAPIA, R; FARINA, F; PAREDES, MC
    The Diels-Alder reaction of the hydroxyquinones 5, 11 and 16 with (E)-1-trimethylsiloxybuta-1,3-diene 3 afforded the corresponding mixture of the regioisomers 6a,b, 12a,b and 17a,b in the ratios 9:1, 8:1 and 11:1, respectively. From these mixtures, the quinones 8, 14 and 19 were obtained by hydrolysis and subsequent oxidation.
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    STUDIES ON QUINONES .27. DIELS-ALDER REACTION OF 8,8-DIMETHYLNAPHTHALENE-1,4,5(8H)-TRIONE
    (1993) VALDERRAMA, JA; ARAYA-MATURANA, R; ZULOAGA, F
    The Diels-Alder reaction of the title quinone 1 with various symmetrical and unsymmetrical dienes in ethanol solution is reported. The cycloaddition takes place, in all cases, across the external quinone double bond affording with cyclopentadiene, buta-1,3-diene and 2,3-dimethylbuta-1,3-diene, the corresponding adducts 3, 4 and 5. The cycloaddition of 1 with 2-methylbuta-1,3-diene and penta-1,3-diene provided 90:10 and 65:35 mixtures of regioisomers 6-7 and 17-18, respectively. Enolisation of these adduct mixtures afforded the corresponding anthracenones 10-11 and 21-22. Compounds 11 and 22, the minor components of the anthracenone mixtures, were synthesized from acetylnaphthalenes 14 and 23.