Dioxasampsones A and B, Two Polycyclic Polyprenylated Acylphloroglucinols with Unusual Epoxy-Ring-Fused Skeleton from Hypericum sampsonii

Abstract

Dioxasampsones A and B (<b>1</b> and <b>2</b>), two new polycyclic polyprenylated acylphloroglucinols with an unusual epoxy-ring-fused skeleton by new ways of cyclization, along with a new nor-PPAPs hypersampson R (<b>3</b>) with the loss of C-31–33 in isopentenyl, were isolated from the aerial parts of Hypericum sampsonii. <b>1</b> possessed an unexpected hexacyclic skeleton with a rare 2,7-dioxabicyclo[2.2.1]­heptane moiety, and <b>2</b> featured a unique tetrahydrofuro­[3,4-<i>b</i>]­furan-fused tricycle­[4.3.1.1<sup>5,7</sup>]­undecane skeleton. The gross structures of the new compounds were determined by extensive NMR spectroscopic methods. Their absolute configurations were deduced by single-crystal X-ray diffraction and ECD calculations

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