Synthesis of the Enantioenriched Tricyclic Core of Tetrapetalones via a Three-Component Aryne Bromoamidation Strategy

We describe a stereoselective approach to the ACD-ring tricyclic core of tetrapetalones, featuring a highly functionalized 6/7/5fused framework. The synthesis is enabled by two key transformations: an aryne-mediated three-component assembly that connects the A- and D-ring fragments while installing a synthetically versatile bromide handle, and a ring-closing olefin metathesis to forge the nitrogencontaining seven-membered C-ring. This sequence efficiently provided the fully assembled ACD-ring tricyclic framework bearing the requisite side chains for subsequent B-ring construction in 18 steps.