13C assignment of diastereotopic C-26 and -27 methyl groups of 24- methylenecholesterol: Steric course of hydrogen migration from C-24 to C-25 during its biosynthesis in higher plants

Abstract

Chemical shifts of the diastereotopic methyl groups (C-26 and C-27) of 24-methylenecholesterol have been unambiguously assigned by synthesizing stereochemically defined 13C-labeled compounds. This allowed us to establish the steric course of hydrogen migration from C-24 to C-25 during the formation of 24-methylenecholesterol from a Δ24-precursor in a tissue culture of Catharanthus roseus.