TCT-Mediated and Water-Controlled Synthesis of Benzofuran-3(2)-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(2)-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 (CH and SMe) in the target molecules, and the construction of the quaternary carbon center in the benzofuran-3(2)-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.