HFIP mediated transition metal-free synthesis of C4-aryl-substituted quinolines.

A transition metal-free method for C4-arylated quinolines synthesis from propargylic chloride and aniline was developed using 1,1,1,3,3,3,-hexafluoroisopropanol (HFIP). During the N-alkylation process, overalkylation was effectively resolved by hydrogen bonding interaction in HFIP. The cyclized intermediates were oxidized to quinolines under ambient air without additional oxidants. A cosolvent system was found to expand the substrate scope to include unstable electron-rich propargyl substrates by preventing acid-induced decomposition.