Benzophenone imine → 3,5-Difluoroaniline

Participants

Reaction Steps

A 4-neck, 500 mL flask was equipped with a mechanical stirrer, a glass stopper, a rubber septum and a condenser with an inert gas inlet. To this flask was added, in order, tris(dibenzylideneacetone)dipalladium (0) (Pd2(dba)3) (25 mg, 0.01 mol %), 1,1′-bis(diphenylphosphino)ferrocene (dppf) (46 mg, 0.03 mol %), sodium tert-butoxide (37 g, 1.4 eq, xylenes (90 mL), 1-chloro-3,5-difluorobenzene (49.2 g, 0.33 mol) and benzophenone imine (50 g, 0.28 mol). The mixture was refluxed for 8 hours until GC analysis confirmed that the benzophenone imine had been consumed. The reaction mixture was cooled slightly, and 150 mL of 2M HCl was added slowly to the reaction mixture with some gas evolution and the mixture was refluxed with sufficient agitation for 45 minutes. While still warm, the reaction mixture was put in a separatory funnel and the aqueous layer was collected. An additional 90 mL of xylenes was added to the separatory funnel and the organic layer was washed with 4×100 mL 1M HCl. The acidic fractions were combined and made alkaline with aqueous conc ammonium hydroxide. The free amine was extracted with 250 mL methyl tert-butyl ether. The organic layer was dried over magnesium sulfate and concentrated in vacuo to yield the expected product in 89% yield.

Provenance & Evidence