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.