TCT-Mediated and Water-Controlled Synthesis of Benzofuran-3(2H)-ones Bearing a Quaternary Carbon Center via a Radical Process Using Dimethyl Sulfoxide as a Dual Synthon

An efficient and attractive method for the synthesis of valuable benzofuran-3(2H)-one derivatives bearing a quaternary center in one step by employing dimethyl sulfoxide (DMSO) as a dual synthon under metal-free conditions has been developed. In this reaction, DMSO activated by cyanuric chloride (TCT) provides two different units (CH₃ and SMe) in the target molecules, and the construction of the quaternary carbon center in the benzofuran-3(2H)-ones can be controlled by the addition of water. Furthermore, the functional group compatibility and synthetic value were demonstrated by scope evaluation and gram-scale experiments. The mechanistic studies show that the reaction may proceed via a radical process.