Boron trifluoride → Methyl 1,2,3,4-tetrahydroquinoline-7-carboxylate

Participants

Reaction Steps

BF3 etherate (30.5 g; 2 equiv.) was first added dropwise to a solution of methyl quinoline-7-carboxylate (20.1 g; 1 equiv.) in 200 ml of methanol. Sodium cyanoboro-hydride (13.5 g; 2 equiv.) was then added in portions. The resulting reaction mixture was stirred for 20 minutes at room temperature and heated overnight at reflux (70-80° C.). When the conversion was complete, the reaction mixture was cooled to room temperature, the solvent was removed under reduced pressure and the residue was taken up in 300 ml of water and extracted 3× with EtOAc. The combined organic phases were dried over sodium sulfate and concentrated under reduced pressure, and the crude product was recrystallised from isopropanol. Methyl 1,2,3,4-tetrahydro-quinoline-7-carboxylate (14 g; 67.3%) was obtained in the form of a colorless solid.

Provenance & Evidence