Visible-Light-Induced Direct Photocatalytic Carboxylation of Indoles with CBr4/MeOH

Article abstract of DOI:10.1002/chem.201503787

Photocatalysis enables the cascade reactions of indoles and CBr₄ in MeOH through a C(sp²)-H functionalization/methanolysis sequence. The title reaction provides an efficient access to indole 2- and 3-carboxylates in a single operation (no preinstallation of protecting as well as directing groups was required) with good yields under mild reaction conditions. Shedding light on indole: The regioselective alkoxycarboxylation of indoles and heteroarenes using the CBr₄/MeOH couple was accomplished through visible-light-induced photoredox catalysis. The described photocatalytic strategy features operational simplicity as well as high functional-group tolerance and represents a direct procedure to access indole carboxylates in generally moderate to good yields (see scheme).