Formal Synthesis of 7-Methoxymitosene and Synthesis of its Analog via a Key PtCl2-Catalyzed Cycloisomerization

A formal synthesis of 7-methoxymitosene is achieved via a key platinum-catalyzed cycloisomerization. The precursor for the Pt catalysis, a fully functionalized benzene intermediate, was prepared via a regioselective electrophilic bromination followed by a chemoselective Sonogashira cross-coupling. It underwent the PtCl2-catalyzed cycloisomerization smoothly despite its hindered and highly electron-rich nature. Analogs of 7-methoxymitosene can be accessed in an expedient manner by following a similar synthetic sequence.