β-Functionalization of indolin-2-one-derived aliphatic acids has been applied in formal [3 + 2] annualtions for catalyst-free and divergent synthesis of two series of structurally interesting 3,3'-spirooxindole γ-butyrolactones that may be attractive for potential drug discovery. These findings also pave the way for further diversity-oriented synthesis of spirooxindoles starting from indolin-2-one-derived aliphatic acids or their derivatives.