Rearrangement of the Tetra- and Tricyclic Skeletons of Pepluanol B to Access the Core Structures of Tigliane- and Myrsinane-Type <i>Euphorbia</i> Diterpenes

Abstract

Pepluanol B is a new Euphorbia diterpene with an unprecedented tetracyclic backbone. However, its biogenetic relationship with known Euphorbia diterpenes is unclear. We report herein that its β-hydroxyl ketone motif could undergo a base-promoted retro-aldol/aldol process in two pathways and afford the skeletons of tigliane- and myrsinane-type Euphorbia diterpenes through the formation of the C8–C14 and C7–C13 bonds, respectively. The retro-aldol/aldol cascade indicates that pepluanol B is possibly a biosynthetic precursor of lathyranes and other relevant dipterpenes.

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