Abstract

The title compound, C<inf>20</inf>H<inf>28</inf>O<inf>3</inf>, known as 'trichodermaerin' [systematic name: (4E)-4,9,15,16,16-pentamethyl-6- oxatetracyclo[10.3.1.0^1,10.0^5,9]hexadec-4-ene-7,13-dione], is a diterpene lactone which was isolated from Trichoderma asperellum. The structure has a tetracycic 6-5-7-5 ring system, with the cyclohexanone ring adopting a twisted half-chair conformation and the cyclopentane ring adopting a half-chair conformation, whereas the cycloheptene and tetrahydrofurananone rings are in chair and envelope (with the methyl-substituted C atom as the flap) conformations, respectively. The three-dimensional architecture is stabilized by C-H..O interactions.