Rh(III)‐Catalyzed Cascade [3 + 3] Spiroannulation of <i>N</i>‐Acyl Ketimines with Iodonium Ylides: Access to Spiro‐<i>N,O</i>‐Ketals

A Rh(III)‐catalyzed cascade CH activation/[3 + 3]spiroannulation of 3‐hydroxy‐3‐arylisoindolin‐1‐ones with iodonium ylides has been developed. The method facilitates the efficient and selective construction of spirocyclic compounds in a one‐pot manner, offering high yields and excellent conversion. The reaction proceeds via a highly regioselective process, resulting in the formation of spiro‐ N,O ‐ketals with remarkable chemo‐ and stereoselectivity. This strategy provides a valuable protocol for the synthesis of complex spirocyclics with potential applications in medicinal chemistry and materials science.