Depsidone synthesis. Part 24. The synthesis of epiphorellic acid 2. A pseudodepsidone and X-ray crystal structure of a grisadienedione epoxide

Abstract

The synthesis of the unusual pseudo-depsidone epiphorellic acid 2 (2){6-hydroxy-3-[5-hydroxy-2-methoxycarbonyl-3-(3-oxopentylphenoxy]-4-methoxy-2-pentylbenzoic acid} by a route involving grisadienedione-depsidone rearrangement and subsequent steps is described. The stereospecific epoxidation of grisadienediones, as proved by X-ray crystallography, is discussed.