Hawaiienols A–D, Highly Oxygenated <i>p</i>‑Terphenyls from an Insect-Associated Fungus, <i>Paraconiothyrium hawaiiense</i>

Abstract

Four new highly oxygenated <i>p</i>-terphenyls, hawaiienols A–D (<b>1</b>–<b>4</b>), have been isolated from cultures of <i>Paraconiothyrium hawaiiense</i>, a fungus associated with the <i>Septobasidium</i>-infected insect <i>Diaspidiotus</i> sp.; their structures were elucidated primarily by NMR experiments. The absolute configurations of <b>1</b> and <b>2</b>–<b>4</b> were assigned by single-crystal X-ray diffraction analysis using Cu Kα radiation and via electronic circular dichroism calculations, respectively. Compound <b>1</b> incorporated the first naturally occurring 4,7-dioxatricyclo­[3.2.1.0^3,6]­octane unit in its <i>p</i>-terphenyl skeleton and showed cytotoxicity toward six human tumor cell lines