Gerardiasterone, a new ecdysteroid with a 20,22,23,25-tetrahydroxylated side chain from the mediterranean zoanthid Gerardia savaglia

Abstract

Homonuclear spin decouplings of the 500 MHz ¹H n.m.r. spectrum, proton shift-correlated 2D (COSY) n.m.r. experiments, selective heteronuclear decouplings of the ¹³C n.m.r. spectrum, and mass spectra of the title compound, as well as ¹H n.m.r. spectra and nuclear Overhauser effect (n.O.e.) experiments with its acetate and acetonide derivatives, suggest the structure 23-hydroxyecdysterone (1a) for the title compound whilst, presumably owing to a flexible 1,3-dioxane ring in the boat conformation, the C-20–C-23 acetonide (1g) fails to provide configurational information as to the chain.