Sesquiterpenoid constituents of the liverwort Marsupella aquatica

Nine new amorphane sesquiterpenoids, (+)-7β-hydroxyamorpha-4,11-diene, (−)-9α-hydroxyamorpha-4,7(11)-diene, (−)-3α-hydroxyamorpha-4,7(11)-diene, (−)-3α-acetoxyamorpha-4,7(11)-diene, (−)-amorpha-4,7(11)-dien-3-one, (+)-2,8-epoxyamorpha-4,7(11)-diene, (+)-5,9-epoxyamorpha-3,7(11)-diene, (−)-2α-hydroxyamorpha-4,7(11)-diene and (−)-2β-acetoxyamorpha-4,7(11)-diene, were isolated from the essential oil of the liverwort Marsupella aquatica, collected near Gaschurn/Montafon, Austria. The isolated compounds and their chemical transformations were investigated using enantioselective GC and extensive spectroscopic studies (HRMS, ¹H, ¹³C and 2D NMR). The absolute configuration of most of the isolated compounds were established by conversions to known compounds. In addition, ¹H, and ¹³C NMR data of (−)-myltayl-4-ene are reported for the first time.