“…Once again, an iminoquinone substructure is evident along with the rare appearance of chlorine in a condensed heterocyclic alkaloid. Four additional alkaloids, isobatzellines A-D (67)(68)(69)(70) were later reported from the same sponge. 51 In spite of the names, isobatzellines are not strictly isomeric with batzellines, but differ in replacement of one of the o-quinone carbonyl groups with an amino group.…”
“…Once again, an iminoquinone substructure is evident along with the rare appearance of chlorine in a condensed heterocyclic alkaloid. Four additional alkaloids, isobatzellines A-D (67)(68)(69)(70) were later reported from the same sponge. 51 In spite of the names, isobatzellines are not strictly isomeric with batzellines, but differ in replacement of one of the o-quinone carbonyl groups with an amino group.…”
“…Almost all the members of pyridoacridine family of marine alkaloids are cytotoxic, and some exhibit specific properties such as inhibition of topoisomerase II, anti-HIV activity, Ca 2+ release activity, metal-chelating properties, or intercalation into DNA − and the efforts toward the synthesis of their polycyclic skeletons and related pyridoacridines are considerable. − Because of the importance that pyridoacridines have acquired since their discovery, a general synthetic route to pyridoacridines would be of great interest and potential utility in medicinal chemistry. …”
Section: Resultsmentioning
confidence: 99%
“…These compounds often exhibit an array of biological activities and a particular chemical behavior that have attracted the interest of many natural product chemists and biochemists. Since 1983, when the structure of amphimedine, the first of these marine alkaloids was reported, many additional examples have been described, and a number of papers have appeared describing synthetic efforts toward and the total synthesis of pyridoacridine alkaloids. − 1 …”
1-BOC-2-lithio-1,4-dihydropyridines were condensed with 3,4-disubstituted cyclobutenediones to produce 1,2-adducts. Neat thermolysis under oxygen-free conditions produced substituted 1,4-dihydroquinoline hydroquinones in which the tert-butoxy residue of the BOC group was displaced by a phenolic residue, generating an oxazolone ring that functioned to protect both rings of the dihydroquinoline hydroquinone from untimely oxidation. Oxidative aromatization with concomitant loss of the oxazolone ring was achieved using 2 equiv of o-chloranil in acetic acid and provided substituted quinoline quinones in good yields. By use of this strategy, a concise synthesis of the pyridoacridine ring system was achieved.
“…10 Thus, the insertion reaction in a less hindered position proceeded at very high yield, giving the desired indole 7 as a single regioisomer (all coupling constants <1Hz). [11][12][13] Hydrolysis of indol 7 under typical reaction conditions provided the new indole 8, which could be regarded as a potential plant growth regulator since such a property has been associated to some aryl homocyclic carboxylic acids.…”
A síntese dos ácidos 5,6-metilenodioxi-indol-3-il-metanóico 8 e 5,6-metilenodioxi-indol-3-ilacético 13 é descrita. Piperonal foi empregado como material de partida, sendo a construção do heterociclo altamente regioespecífica e está fundamentada na reação de Hemetsberger do correspondente β-azidoestireno. O composto 8 foi obtido como intermediário pivotal na preparação de 13, tendo-se conduzida a reação de Mannich para a introdução da cadeia lateral alquílica. A rota sintética empregada englobou oito etapas e conduziu a formação de 13 com rendimento total de 26%. A formação do heterociclo indólico via ciclização redutiva de o, β-dinitroestireno é também apresentada.The synthesis of 5,6-methylenedioxy-indol-3-yl-methanoic acid 8 and 5,6-methylenedioxyindol-3-yl-acetic acid 13 is described. Piperonal was employed as starting material, and the construction of the heterocyclic ring based on the Hemetsberger reaction of the corresponding β-azidostyrene was highly regiospecific. Compound 8 was obtained as a key intermediate towards 13, and a Mannich reaction was used to introduce the required alkyl side chain. The route comprised eight steps giving 13 in 26% overall yield. The formation of the indolic ring via reductive cyclisation of o, β-dinitrostyrene is also presented.
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