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

• Published in: Journal of organic chemistry Vol. 84; no. 16; pp. 9869 - 9896
• Main Authors: Sen, Chiranjit, Sahoo, Tapan, Singh, Harshvardhan, Suresh, Eringathodi, Ghosh, Subhash Chandra
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 16.08.2019; Amer Chemical Soc
• Subjects: alcohols; aminoquinolines; aromatic hydrocarbons; carboxylation; cations; chemical structure; Chemistry; Chemistry, Organic; electron transfer; mass spectrometry; organic chemistry; photocatalysis; Physical Sciences; Science & Technology; sulfonamides; QUINOLINE N-OXIDES; POSITION; REGIOSELECTIVE C; ALKYLATION; ARYLATION; MERGING PHOTOREDOX CATALYSIS; INHIBITORS; C-H FUNCTIONALIZATION; METAL-FREE; C5-H PHOSPHONATION
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/acs.joc.9b00942

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.