Dearomatisation approaches to spirocyclic dienones via the electrophilic activation of alkynes

Abstract

Two complementary dearomatising spirocyclisation protocols to generate spirocyclic dienones from anisole and phenol-tethered ynones are described, each proceeding via electrophilic alkyne activation. The first approach focuses on the spirocyclisation of para-substituted anisoles using either SnCl₂·2H₂O or Cu(OTf)₂. The second approach, which enables the spirocyclisation of both ortho- and para-substituted phenols, uses silica-supported AgNO₃ to generate similar scaffolds with much greater efficiency. Initial asymmetric studies are also outlined.