Reductive 3-Silylation of Benzofuran Derivatives via Coupling Reaction with Chlorotrialkylsilane.

Reductive silylation of benzofurans with an electron-withdrawing group by a magnesium metal and the subsequent oxidative rearomatization by DDQ gave the selective formation of less reported 3-silylated benzofurans in moderate to good yields under mild reaction conditions with wide substituent scope. The silyl group introduced on the five-membered ring by the reductive coupling could survive with no elimination throughout the oxidation process. The silylated heteroaromatic skeleton is useful as an intermediate in organic synthesis, and its practical utility was also demonstrated by several transformation reactions.