Structurally well-defined oligomers are fundamental for the functionality of natural molecular systems and key for the design of synthetic counterparts. Herein, we describe a strategy for the efficient synthesis of individual stereoisomers of 1,2-naphthylene oligomers by iterative building block additions and consecutive stereoselective arene-forming aldol condensation reactions. The catalyst-controlled atropoenantioselective and the substrate-controlled atropodiastereoselective aldol condensation reaction provide structurally distinct ter- and quaternaphthalene stereoisomers, which represent configurationally stable analogues of otherwise stereodynamic, helically shaped ortho-phenylenes.

Molecular scaffolds with multiple rotationally restricted bonds allow a precise spatial positioning of functional groups. However, their synthesis requires methods addressing the configuration of each stereogenic axis. We report here a catalyst-stereocontrolled synthesis of atropisomeric multiaxis systems enabling divergence from the prevailing stereochemical reaction path. By using ion-pairing catalysts in arene-forming aldol condensations, a strong substrate-induced stereopreference can be overcome to provide structurally well-defined helical oligo-1,2-naphthylenes. The configuration of up to four stereogenic axes was individually catalyst-controlled, affording quinquenaphthalenes with a unique topology.

The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides various indispensable products and intermediates in a sustainable manner. While formyl functionalities typically undergo irreversible oxidations when activating an...

At opologically well-defined atropisomeric teraryl monophosphine ligand system, prepared by ah ighly stereoselective arene-forming aldol condensation combined with ad irect ester-to-anthracene transformation, is described herein. The ligands were evaluated for gold(I)catalyzed [2+ +2] cycloadditiona nd cycloisomerization reactions as well as au nique intramolecular Pd-catalyzedC ÀN cross-coupling for the atroposelective synthesis of a Naryl-indolineb earing aC ÀNs tereogenic axis. The ligand structure induced up to 95:5 stereoselectivity in the asymmetric allylic alkylation reaction and features an interesting dynamic behavior as observed by X-ray crystallographic studies.

The fundamental role that aldol chemistry adopts in various disciplines, such as stereoselective catalysis or the biosynthesis of aromatic polyketides, illustrates its exceptional versatility. On the one hand, numerous aldol addition reactions reliably transfer the stereochemical information from catalysts into various valuable products. On the other hand, countless aromatic polyketide natural products are produced by an ingenious biosynthetic machinery based on arene-forming aldol condensations. With the aim of complementing aldol methodology that controls stereocenter configuration, we recently combined these two tenets by investigating small-molecule-catalyzed aldol condensation reactions that stereoselectively form diverse axially chiral compounds through the construction of a new aromatic ring.

By taking inspiration from the fascinating biosynthetic machinery that creates aromatic polyketides, our group investigates analogous reactions catalyzed by small molecules. We are particularly captivated by the prospects of intramolecular aldol condensation reactions to generate different rotationally restricted aromatic compounds. In a first project of our independent research group, a highly stereoselective amine catalyzed synthesis of axially chiral biaryls, tertiary aromatic amides and oligo-1,2-naphthylenes has been developed. In this article, we outline the twists and turns for our escape from the aromatic flatland to structurally intriguing chiral arene scaffolds relevant for various fields of application.

Strukturell wohldefinierte Oligomere sind fundamental wichtig für die Funktionalität natürlicher molekularer Systeme und sind der Schlüssel für synthetische Analoga. Wir berichten hier über eine Strategie für die effiziente Synthese von Oligo-1,2-naphthylen-Stereoisomeren mittels wiederholter Bausteinaddition und anschließender stereoselektiver,a renbildender Aldolkondensation. Die katalysatorkontrollierte atropenantioselektive und die substratkontrollierte atropdiastereoselektive Aldolkondensation ergeben Ter-und Quaternaphthalin-Stereoisomere,d ie konfigurativ stabile Gegenstü-ckez ud en ansonsten stereodynamischen, helikalen orthoPhenylenen darstellen.

No abstract