Discovery and synthesis of flueggeacosines D–F and securingine J

Four new securinega alkaloids, flueggeacosines D–F and securingine J, have been discovered from Flueggea suffruticosa. Flueggeacosines D and E possess dimeric frameworks incorporating a benzoquinolizidine motif derived from allosecurinine backbone. A concise synthetic strategy combining TBADT-catalyzed radical hydroacylation and Mo(CO)₆-mediated reductive rearrangement enabled efficient access to these complex alkaloids. Our synthetic approach also realized a synthesis-based natural product anticipation that predicted and confirmed the existence of flueggeacosine F and securingine J in F. suffruticosa. Furthermore, oxidative rearrangements of flueggeacosine A furnished flueggeacosines D and F, supporting a plausible biosynthetic linkage. These findings establish a unified route to oxidized dimeric securinega alkaloids and demonstrate the synergy of synthesis and biosynthetic reasoning in natural product discovery.