Construction of the highly oxidized bicyclo[3.2.1]octane CD ring system of aconitine via a late stage enyne cycloisomerization

A strategy for synthesizing the highly oxidized bicyclo[3.2.1]octane CD rings of aconitine is reported. The key features of the synthesis include a ring-closing metathesis to form the C-ring as well as the application of a ruthenium-catalysed enyne cycloisomerization to assemble the bridged CD ring system of aconitine.