Visible Light-Promoted Photocatalytic C‑5 Carboxylation of 8‑Aminoquinoline Amides and Sulfonamides via a Single Electron Transfer Pathway

An
efficient photocatalytic method was developed for the remote
C5-H bond carboxylation of 8-aminoquinoline amide and sulfonamide
derivatives. This methodology uses in situ generated •CBr3 radical as a carboxylation agent with alcohol and
is further extended to a variety of arenes and heteroarenes to synthesize
the desired carboxylated product in moderate-to-good yields. The reaction
proceeding through a single electron transfer pathway was established
by a control experiment, and a butylated hydroxytoluene-trapped aryl
radical cation intermediate in high-resolution mass spectrometry was
identified.