Total Synthesis of (-)-Flueggeacosine C

Herein we describe a total synthesis of the heterodimeric securinega alkaloid (-)-flueggeacosine C (8). The convergent synthetic strategy is based on a Liebeskind-Srogl cross-coupling reaction that combines a benzoquinolizidine fragment with a securinine-type alkaloid. An acyloxy nitroso ring-expansion was employed as the key step in accessing benzoquinolizidine 9, and a novel intramolecular Diels-Alder reaction of an allenic acid-containing pyridone expeditiously delivers the skeleton of the securinine-type fragment (16). Finally, a Cu-catalyzed hydroboration-oxidation sequence was employed to regio- and diastereoselectively introduce the secondary alcohol found in 8.