A series of cation-like cyclizations and rearrangements, known as the Stork-Eschenmoser hypothesis, were identified in the biosynthesis of the triterpene lanosterol. Lanosterol is a precursor in the b...A series of cation-like cyclizations and rearrangements, known as the Stork-Eschenmoser hypothesis, were identified in the biosynthesis of the triterpene lanosterol. Lanosterol is a precursor in the biosynthesis of steroids.