TOTAL SYNTHESES OF HELIANNUOLS: AN OVERVIEW

Nature has always been recognized as a rich source for the identification of new drug candidates. Heliannuols have drawn wide attention because of their interesting structural scaffolds and biological potential. Biological evaluation has shown that heliannuols have the allelopathic activity and may be used as lead compounds in herbicides. The synthesis of this family of molecules has always been challenging because of their unique scaffold and multiple chiral centers. Up to now, there have been 32 synthetic routes toward these kinds of natural compounds and a mini-review; however, the synthesis of heliannuols F, I, and J have not been reported yet. Many different strategies such Julia coupling, Dickman condensation, ring-closing metasis, ring contraction or expansion, rearrangement, and intramolecular epoxide opening have been employed in these syntheses. More efficient and highly enantiocontrolled and ecofriendly strategies should be developed for sustainable chemistry.