Studies Toward The Synthesis Of Lomaiviticins A and B and Englerin A

Part I: Studies toward the central core of lomaiviticins A and B Lomaiviticins A and B are novel C2-symmetric dimeric molecules with profound cytotoxic activity. The most challenging feature of these molecules is the densely functionalized central core. Despite the effort by several research groups, the total synthesis of lomaiviticins has not been reported so far. We envisioned the synthesis of the lomaiviticin core by an unprecedented Diels-Alder dimerization of ortho-quinols and masked ortho-benzoquinones, followed by the fragmentation of the extra carbon-carbon bond. This chapter describes the stereoselective elaboration of the ortho-quinol and masked ortho-benzoquinone dimers to the fragmentation precursors and the unsuccessful attempts to effect the scission of the extra bond. Part II: Studies toward the total synthesis of englerin A Englerin A is a new guaiane sesquiterpene isolated recently in 2008. It has been shown to be a selective renal cancer inhibitor. We envisioned the synthesis of englerin A via a novel strategy featuring Wagner-Meerwein rearrangement followed by intramolecular cation trapping. This chapter describes the stereoselective synthesis of the key cis-decalin intermediate from: -)-carvone and the unsuccessful attempts to realize the skeletal rearrangement