Photoredox Catalyzed Strain-Release Driven Synthesis of Functionalized Spirocyclobutyl Oxindoles

29 March 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Spirocyclobutyl oxindoles have garnered substantial attention in drug discovery and pharmaceuticals owing to their wide range of biological activities. Strain-release in small-ring compounds is a powerful strategy to enable efficient access to complex molecules. In this study, we have successfully realized a photoredox-catalyzed strain-release radical spirocyclization approach to attain functionalized spirocyclobutyl oxindoles. A diverse array of radicals, such as sulfonyl, phosphonyl, and trifluoromethyl, were added efficiently to the strained C-C bond of bicyclobutanes (BCBs) to afford a library of spirocyclobutyl oxindoles. Furthermore, the obtained products could be transformed into valuable building blocks. The observed reactivity and selectivity have been rationalized based on density functional theory calculations.


Photoredox catalysis
Radical cascade

Supplementary materials

Supporting Information
General experimental procedures, optimization of the reaction, mechanistic experiments, X-ray structure of 3a and 3b, characterization and crystal data, and NMR spectra of new compounds (PDF).

Supplementary weblinks


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