First partial synthesis of α-boswellic acid from oleanolic acid

Abstract

While β-boswellic acid is very readily available by extraction from frankincense resin, the accessibility of α-boswellic from the resin involved great effort and tedious purification procedures. Alternatively, a partial synthesis from readily available oleanolic acid was developed, the key steps of which are a reduction of the carboxyl group C-28 furnishing a methyl group, followed by palladium-assisted oxidation of the methyl group C-24, and configurational inversion at C-3. • α-Boswellic acid, a main ingredient of frankincense, has previously been isolated. • Contrary to its analog, β-boswellic acid, its availability is diminished. • A first partial synthesis from well accessible oleanolic acid was developed.