Synthesis of Novel Angular Heterocyclic Lignans by an InCl₃‐Catalyzed Friedel–Crafts‐Type Cyclization

Abstract

The synthesis of a 1‐aryltetralin privileged structure‐based library of novel angular heterocyclic lignans is described. Indolotetralins 3, tetrahydroquinolinotetralins 4, and thiochromanotetralins 5 were obtained from the methyl ester of thuriferic acid 2 according to a three‐step procedure involving an InCl3‐catalyzed Friedel–Crafts‐type cyclization as the key step.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Catalytic Functionalization of Indoles in a New Dimension

“…The tendency of indoles to couple regioselectively with enones was recently exploited by Florent, Bertounesque, and co‐workers in the synthesis of pharmacologically active angular heterocyclic lignans ( 8 ) 24. The authors elegantly employed a double indium(III)‐catalyzed Friedel–Crafts alkylation25 of variously functionalized indoles with methyl thuriferates such as 5 .…”

Palladium-Mediated Oxidative Annulation of δ-Indolyl-α,β-Unsaturated Compounds toward the Synthesis of Cyclopenta[b]indoles and Heterogeneous Hydrogenation To Access Fused Indolines

“…The structural diversity associated with biologically active natural and synthetic compounds possessing the cyclopenta­[ b ]­indole motif continues to inspire the development of novel approaches for preparing this heterocycle. Cyclopenta­[ b ]­indole systems have been prepared via Fischer syntheses, Yonemitsu condensations, Nazarov cyclizations, electrophilic substitution of indoles, [3,3]-sigmatropic rearrangements, [3 + 2] cycloadditions, vinylogous Michael addition/Friedel–Crafts reactions, bismuth (III)-catalyzed condensations, gold (I)-catalyzed Rautenstrauch rearrangements, Dieckmann condensations, Friedel–Crafts reactions, Heck–Suzuki cascades, and enzymatic syntheses . The functionalization of indolyl-methanol can also be used to prepare cyclopenta­[ b ]­indoles …”

Katalytische Funktionalisierung von Indolen in einer neuen Dimension

“…Die regioselektive Reaktion von Indolen mit Enonen haben sich kürzlich Floren, Bertounesque und Mitarbeiter in der Synthese von pharmakologisch aktiven, gewinkelten heterocyclischen Lignanen ( 8 ) zunutze gemacht 24. Sie beschrieben die elegante Anwendung einer Indium(III)‐katalysierten FCA25 von verschiedenartig funktionalisierten Indolen mit Methylthuriferat‐Estern wie 5 (Schema ).…”