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Updated: Oct 25, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Condition-Controlled Chemoselectivity Switching of Spiro-Epoxy Oxindoles: Access to Spiro-Oxetane Oxindoles
Ananda Shankar Mondal1,2, Ayan Chatterjee1,2, Ankita Biswas1,2
1Center of Biomedical Research, Sanjay Gandhi Post-Graduate Institute of Medical Sciences Campus, Raebareli Road, Lucknow226014, India.
Abstract:
A condition-controlled switch in chemoselectivity has been achieved in the reaction of spiro-epoxy oxindoles with sulfur ylides. In contrast to the previously observed cyclopropanation pathway, Lewis acid catalysis with tert-BuOK in tert-BuOH at elevated temperature redirects the reaction toward a Corey-Chaykovsky-type ring expansion, affording spiro-2'-oxetane oxindoles in good yields. This transformation provides direct access to oxindoles bearing a strained four-membered oxetane ring at the C3 position, a spirocyclic motif of growing interest in medicinal chemistry.
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