Chemoselective Synthesis of 2-Ester and Dioxolane Derivatives of 20-Hydroxyecdysone and Poststerone

Abstract

Chemoselective approaches to the synthesis of ester and cyclic acetal derivatives of ecdysteroids with 5-bromovaleric and lipoic acids and aromatic heterocyclic aldehydes were proposed. Chemoselective formation of 2-monoester derivatives (compounds 4–7) or dioxolane adducts (compounds 8–10) occurred during condensation of an ecdysteroid with an acid or aldehyde. Compound 8, which was prepared by acid-catalyzed condensation of 20-hydroxyecdysone with furfuraldehyde, was an analog of the phytoecdysteroid serfurosterone A, which was isolated from the plant Achyranthes bidentata.