Strategien für die Synthese von Naturstoffen mit benachbarten stereogenen quartären Kohlenstoffatomen

Abstract

Anhand zwölf repräsentativer Beispiele stellen wir in diesem Aufsatz Strategien für die Totalsynthese komplexer Naturstoffe vor, die zwei oder mehr benachbarte stereogene quartäre Kohlenstoffatomen in ihren komplexen Molekülstrukturen enthalten. Das Hauptaugenmerk liegt dabei auf den Methoden zur Konstruktion quartärer stereogener Kohlenstoffzentren, einschließlich der Synthese desselben Naturstoffs auf verschiedenen Wegen durch unterschiedliche Forschergruppen; dies soll die Vielfalt der Gedankengänge sowie die Individualität kreativer Leistungen verdeutlichen. Ein Kompendium von ausgewählten Naturstoffen mit zwei oder mehr benachbarten stereogenen quartären Kohlenstoffatomen sowie von Schlüsselreaktionen ihrer jeweiligen Total‐ oder Partialsynthesen findet sich in den Hintergrundinformationen.

Formation of δ-Lactones by Cerium-Catalyzed, Baeyer–Villiger-Type Coupling of β-Oxoesters, Enol Acetates, and Dioxygen

“…Four prominent examples are warfarin ( 1 ), an anticoagulant; the topoisomerase I inhibitor irinotecan ( 2 ), a camptothecin derivative; the antimalarial artemisinin ( 3 ); and ochratoxin A ( 4 ), a toxin from Aspergillus species (Figure ). There are several strategies in the literature to prepare lactones with an α-quaternary carbon center . However, the most powerful method to access δ-lactone derivatives is the Baeyer–Villiger oxidation of a cyclopentanone derivative, which is classically achieved by peroxycarboxylic acids, although several enzymatic methods were also reported in recent years …”

Complex Molecule Synthesis, a Personal View

“…In the present decade the cutting edge of complex molecule synthesis concerns the number of adjacent quaternary stereocenters in the target . Leading syntheses managed in several instances to build up two, and in a few cases three, adjacent quaternary stereogenic centers.…”

Access toward steroid skeleton and its derivatives via copper‐catalyzed intramolecular cyclization: A short synthesis of estradiol and estrone

“…Small modification in the core structure of steroids leads towards extensive changes in their biological activities and may emerge as a new drug to treat different diseases. But the synthesis of steroids requires addressing many challenges including the installation of all‐carbon quaternary stereocenters, [9] multiple redox manipulations, [10] and assembly of polycyclic ring systems with defined stereo chemistries at the ring junctions [11] . Nowadays, transition metal catalyzed cycloisomerizations of poly‐unsaturated systems to form polycyclic natural compounds are a matter of interest.…”