Tetracyclic Benzo Research Articles

Polyfunctionalized Aryllead Triacetates in a Cascade Synthesis of Tetracyclic Isochromanocoumarin‐Type Compounds.

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Polyfunctionalized Aryllead Triacetates in a Cascade Synthesis of Tetracyclic Isochromanocoumarin-Type Compounds

The three-step one-pot α-arylation-annulation sequence leading to the reaction of 4-hydroxycoumarins with in situ generated 2-(bromomethyl)aryllead triacetates carried out in the presence of a combination of ortho-phenantroline-potassium tert-butoxide afforded tetracyclic benzo[b]pyran compounds in good to high yields.

An Intramolecular Diels—Alder Route to Novel Tetracyclic Benzo[b]thiophene Derivatives.

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An intramolecular Diels–Alder route to novel tetracyclic benzo[ b]thiophene derivatives

A one-pot route to 3-benzo[ b]thiophen-2-yl-acrylates ( 2 ) from the corresponding thiophenols ( 1 ) is reported. Ester reduction and subsequent hydroxyl esterification deliver psuedo trienoates ( II ) which undergo an intramolecular Diels–Alder (IMDA) reaction to give two 2-oxa-9-thiacyclopenta[ b]fluoren-3-one products ( I )—the major Diels–Alder product rearomatizes to 7 .

Antiestrogenic activities of 3,8-dihydroxy-6,11-dihydrobenzo[a]carbazoles with sulfur-containing side chains.

The objective of this study was to explore whether the conversion of the 2-phenylindole system into the tetracyclic benzo[a]carbazole changes the endocrine profile when the side chain structure was kept constant. Five different sulfur-containing side chains were linked to the nitrogen of the tetracycle. The biological evaluation revealed that the character of the indole derivatives remained unchanged after the conversion to the respective benzocarbzoles but the potency decreased by one order of magnitude. In vitro, all derivatives acted as pure antiestrogens without any agonist activity. They strongly inhibited the growth of estrogen-sensitive MCF-7 breast cancer cells with IC50-values in the nanomolar range. In the mouse uterine weight test, the derivatives with an aliphatic side chain were devoid of estrogenic activity and antagonized the effect of estradiol. The presence of an aromatic ring in the side chain gave rise to significant agonist activity in vivo independently of the carrier structure. All data revealed the equivalence of both carrier structures in respect to the endocrine profile but showed a decrease in potency upon the conversion of the 2-phenylindole system into the benzocarbazole structure.