3-Oxo-18α-olean-28,13β-olide.

Area of Science:

• Organic Chemistry
• Computational Chemistry
• Crystallography

Background:

• Oleanolic acid is a natural triterpenoid with diverse biological activities.
• Lactonization is a key reaction in modifying natural products.
• Understanding molecular geometry is crucial for structure-activity relationship studies.

Purpose of the Study:

• To synthesize and characterize a specific terpene lactone derivative of oleanolic acid.
• To investigate the stereochemical outcome of the lactonization reaction.
• To validate experimental structural data using quantum chemical calculations.

Main Methods:

• Synthesis of the terpene lactone using bis-muth trifluoro-methane-sulfonate.
• X-ray crystallography to determine the solid-state structure.
• Quantum chemical ab-initio Roothaan Hartree-Fock calculations for geometry optimization.

Main Results:

• The 28,13β-lactone of oleanolic acid was successfully prepared.
• X-ray diffraction revealed an inversion of the 18-H orientation during lactonization.
• Computational methods accurately reproduced experimental bond lengths, angles, and molecular conformation.

Conclusions:

• The synthetic route provides a well-defined terpene lactone.
• The study confirms the stereochemical inversion during the lactonization process.
• Quantum chemical calculations serve as a reliable tool for predicting and validating molecular structures and conformations.