Formal total synthesis of histrionicotoxin alkaloids via Hg(OTf)2-catalyzed cycloisomerization and SmI2-induced ring expansion

Abstract

The efficient formal total synthesis of histrionicotoxin alkaloids was achieved. In this process, two key reactions were used to construct a core 1-azaspiro[5.5]undecane framework common to histrionicotoxins: a mercuric triflate (Hg(OTf)₂)-catalyzed cycloisomerization of a linear substrate, which was developed in our laboratory, and a samarium iodide (SmI₂)-mediated ring expansion.