Constructing All-Carbon Quaternary Centers from Ketones via Titanacyclobutanes: Rapid Access to Azaspiro[3.n]alkanes

Quaternary carbon centers pose a significant challenge in chemical synthesis. Harnessing the underexplored reactivity of titanacyclobutane intermediates, a strategy to construct functionalized all-carbon quaternary centers from ketones is described. This methodology streamlines access to a wide variety of azaspiro[3.n]alkanes that have emerged as valuable three-dimensional inputs for drug discovery.