Surfactant Micelles Enable Metal-Free Spirocyclization of Keto-Ynamides and Access to Aza-Spiro Scaffolds in Aqueous Media

Micellar solutions of cetyltrimethylammonium bromide (CTAB) surfactant allow the spirocyclization of keto-ynamides in an aqueous medium without recourse to transition-metal catalysis, enabling access in water to naturally occurring aza-spiro compounds with potential in drug discovery. The reaction was monitored by dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM), which determined the morphology and change in size of the micelles before and after incorporation of the substrate and achievement of 5-endo-dig cyclization inside the micelles.