Stereochemistry of reduction of the 24,25-double bond in the biosynthesis of tigogenin in Digitalis lanata

Abstract

In tigogenin [(25R)-5α-spirostan-3β-ol] biosynthesized in Digitalis lanata a 4-pro-R-proton of mevalonic acid occupies the 24-pro-S-position, which indicates that reduction of Δ²⁴-biosynthetic intermediates occurs with trans-stereochemistry.