Recent Advances in the Synthesis of Spirooxindoles: A Comprehensive Review Organized by Ring Size, Heteroatom Incorporation, and Synthetic Approaches.

Spirooxindole compounds have attracted considerable research interest due to their distinctive structural features and remarkable biological properties. In recent years, a wide range of synthetic strategies has been developed to construct spirooxindoles, particularly those featuring a spiro-carbon Linked to diverse Heterocyclic or carbocyclic frameworks, further enhancing their importance. Given the breadth of these synthetic approaches, a comprehensive review is crucial to providing a systematic overview of the field and facilitate access to various methodologies. This review provides a thorough analysis of current developments in spirooxindole synthesis, covering research published from 2020 to 2024. The classification is organized into four main sections based on the size of the ring attached to the spiro-carbon: three-membered, five-membered, six-membered, and seven-membered rings. These rings may be carbocyclic or may contain one or two heteroatoms, such as nitrogen, oxygen, or sulfur, further influencing the diversity of synthetic strategies and the properties of the resulting spirooxindoles.