Stereospecificity in the side-chain formation of 24β-ethylsterols in tissue cultures of Trichosanthes kirilowii
Abstract
In the biosynthesis of 22-dihydrochondrillasterol (4) from [2-13C,2-2H3] acetate and [1,2-13C2] acetate in cell cultures of Trichosanthes kirilowii, the hydrogen atom coming from C-4 of mevalonic acid was revealed by 13C n.m.r. spectroscopy to be located at C-24, and that the protonation at C-25 of the 24β-ethyl-Δ25 precursor, to form the saturated side chain of (4), was most likely to occur from the Re-face.