A novel synthesis of brassinolide and related compounds
Abstract
A stereoselective synthesis of the natural promoting steroids, brassinolide, homobrassinolide, and typhasterol is described, which involves construction of a side chain by lactonisation of Z-(5) under acidic conditions to give an α,β-unsaturated δ-lactone (6) with the inversion of the configuration at C-22 of the epoxy steroid in quantitative yield.