Potential allelopathic activity of natural plant heliannanes: A proposal of absolute configuration and nomenclature

Proposals for the biogenesis and absolute configuration of 12 heliannanes ( based on modified Mosher methodology) are presented. The proposal of biogen esis is discussed for both possible origins-terrestrial or marine. Due to t he different skeleton types that have been found, a systematic nomenclature based on the different heterocycle ring size is proposed. Phytotoxicity of compounds 5-11 suggests that these new bioactive sesquiterpenes may be inv olved in sunflower defense against dicotyledon species, and they could be u sed as natural herbicide templates.