Fungal metabolites. Part 45: The sesquiterpenes of Collybia maculata and Collybia peronata

The sesquiterpenes of Collybia maculata and C. peronata (Basidiomycetes) ha ve been reinvestigated. In addition to collybolide, isocollybolide and deox ycollybulidol, five new structurally related sesquiterpene lactones have be en isolated. The structures have been established by spectroscopic methods. Stereochemical assignments required a derailed conformational investigatio n, which has been carried out at the AM1 level fur all compounds, and at th e B3LYP level for some of them. This led to the inversion of the previously proposed C-7 configuration of deoxycollybolidol. The absolute configuratio n of collybolides could tentatively be inferred from CD studies. (C) 2001 E lsevier Science Ltd. All rights reserved.