Substrate‐Controlled [2 + 3] and [3 + 3] Annulation of Bisnucleophiles: Access to Oxygen Heterocycles

Here, a facile and efficient [2 + 3] and [3 + 3] annulation of bisnucleophiles have been developed, affording various methylenetetrahydrofuran spirooxindole and methylenetetrahydropyrano[2,3‐c]pyrazoles derivatives under mild reaction conditions. This method provides facile and alternative strategies for the construction of functionalized oxacyclic products in moderate to good yields. In addition, the gram‐scale reaction and synthesis transformations are performed to examine the practicability of this methodology.