Diastereoselective synthesis of cyclopentapyridazinones via radical cyclization: synthetic studies toward halichlorine

The pyridazinone ring system serves as an excellent scaffold for the diastereoselective preparation of novel cis-fused cyclopentapyridazinones utilizing the directed 5-exo radical cyclization approach. This overall approach was successfully employed in the preparation of a functionalized aza-spirocycle.