Hydrochloric Acid → 6,7-Difluoro-2-methylquinoline

Participants

Reaction Conditions

Reaction Steps

Crotonaldehyde (226.34 g, 3.23 tool) in 100 mL of 2-butanol was added dropwise to a refluxing solution of 3,4-difluoroaniline (417.27 g, 3.23 tool), p-chloranil (794.65 g, 3.23 mol) and HCl conc. (808 mL) in 5.4 L of 2-butanol. After 2 hours of heating 2.7 L of solvent was removed under vacuum at ca. 60° C. Then 2 L of toluene was added to the reaction mixture followed by removal of 2.5-3 L of solvent until a very pasty solid formed. THF (2L) was added and the mixture heated 30 min. after which it was cooled to 0° C. The solid was collected and washed with THF until pure by tlc. The solid was then dissolved in aq. K2CO3 /EtOAc and the organic phase separated. The aqueous phase was extracted with EtOAc (2X) and the organic phases combined, dried over MgSO4, and the solvent removed. The product was crystallized in the minimum amount of EtOAc to give 328.08 g (57%) of the title compound.

Provenance & Evidence