Derivatives of (–)‐Isosteviol with Expanded Ring D and Various Oxygen Functionalities

Abstract (–)‐Isosteviol is a unique ex‐chiral‐pool building block that is readily available. Both functional groups are aligned in a concave manner. The methyl moiety on the backbone also points in this direction, creating a strong asymmetric environment close to these functional groups. The slightly divergent orientation of the keto and carboxy functions limits its use in the construction of supramolecular architectures as optically pure divalent building blocks. By selective transformations, ring D of (–)‐isosteviol can be expanded and equipped with oxygen‐containing functionalities, providing a variety of useful and rigid building blocks with defined stereochemistry.