Synthesis of Sulfonyloxindoles via Functional Group Exchange Between 3-Sulfonylphthalide and Isatylidenemalononitrile

An unusual reactivity of 3-sulfonylphthalides with isatylidenemalononitriles has been exploited to provide an efficient entry into 3-sulfonyloxindoles. Although a Hauser-Kraus mechanism can be visualized for the observed transformation, a more probable mechanism, based on control experiments and spectroscopic studies, involves Michael addition of sulfonylphthalide to isatylidenemalononitrile followed by elimination and re-addition of sulfonyl and malononitrile functionalities in an overall functional group exchange between phthalide and oxindolyl moieties. We have also demonstrated the synthetic applications of the sulfonyloxindoles in selected reactions such as conjugate addition and aromatization.

Automated summary

The unusual reactivity of 3-sulfonylphthalides with isatylidenemalononitriles has been studied to provide an efficient entry into 3-sulfonyloxindoles, showing a mechanism involving Michael addition, elimination, and re-addition of functional groups. The synthetic applications of the sulfonyloxindoles in reactions such as conjugate addition and aromatization have also been demonstrated.