ABSTRACT
A topologically well-defined atropisomeric teraryl monophosphine ligand system, prepared by a highly stereoselective arene-forming aldol condensation combined with a direct ester-to-anthracene transformation, is described herein. The ligands were evaluated for gold(I)-catalyzed [2+2] cycloaddition and cycloisomerization reactions as well as a unique intramolecular Pd-catalyzed C-N cross-coupling for the atroposelective synthesis of a N-aryl-indoline bearing a C-N stereogenic 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.
ABSTRACT
Terpenes constitute one of the most structurally varied classes of natural products. A wide range of these structures are produced in nature by type I terpene cyclase enzymes from one single substrate. However, such reactivity has proven difficult to reproduce in solution with man-made systems. Herein we report the shortest synthesis of the tricyclic sesquiterpene presilphiperfolan-1ß-ol to date, utilizing the supramolecular resorcinarene capsule as catalyst for the key step. This synthetic approach also allows access to unnatural derivatives of the natural product, which would not be accessible through the biosynthetic machinery. Additionally, this study provides useful insight into the biosynthesis of the presilphiperfolanol natural products, including the first experimental evidence consistent with the proposed biosynthetic connection between caryophyllene and the presilphiperfolanols.
