A new atisane diterpene: ent-16α-hydroxyatis-13-en-3-one from Androstachys johnsonii prain

Abstract

The title diterpene, a rare example of the naturally occurring ent-atis-13-ene type, has been isolated as the 2-benzylidene derivative from the heartwood hexane extract of Androstachys johnsonii Prain. Its structure was determined by n.m.r. and X-ray crystallography. It is suggested that the title compound is biogenetically produced from an ent-12-oxybeyer-15-ene precursor. An interesting reaction reported here was found to convert a vicinal diol into a monoketone using the diethyl azodicarboxylate–triphenylphosphine–benzoic acid system.