Oxidative and reductive transformations of 11-keto-β-boswellic acid

Extraction of frankincense—a fragrant resin obtained from plants of the genus Boswellia—followed by an oxidation furnished high yields of (3β) 3-O-acetyl-11-keto-β-boswellic acid (β-AKBA), a valuable starting material for accessing boswellic acid derivatives. Boswellic acids are fascinating triterpenoic acids that exhibit different biological activities. However, their biological potential, as well as that of their derivatives, remained unexploited due to their limited availability. In this study we were able to prepare derivatives of 11-keto-β-boswellic acid in good to excellent yields by oxidative and reductive transformations mainly in rings A and C of the triterpenoid skeleton. Among other transformations, a highly cytotoxic endoperoxide was obtained in excellent yields.

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