Total Synthesis of (±)-Impatien A via Aza-Heck Cyclization

The first total synthesis of the
natural product impatien A is
described. This concise synthesis features an aza-Heck cyclization
to construct the complex spirocyclic ring system and provides a rare
example of the use of aza-Heck cyclizations in complex molecule synthesis.
To enable this key cyclization of an electrophilic nitrogen atom with
a tetrasubstituted alkene, we utilized high-throughput experimentation
to identify a new ligand and ultimately deliver impatien A in seven
steps from known compounds.