Double-Carboxylation of Two C-H Bonds in 2-Alkylheteroarenes Using LiO- t-Bu/CsF.

We describe the double-carboxylation of two C-H bonds (i.e., at the benzylic and the β-positions) in 2-alkylheteroarenes using a combination of LiO- t-Bu and CsF. A diverse range of substrates, namely benzothiophene, thiophene, benzofuran, furan, and indole derivatives, are efficiently converted into the doubly carboxylated products. A variety of functionalities (i.e., methyl, methoxy, halogen, cyano, ester, ketone, and amide moieties) are well tolerated.