Triphenylphosphine → 2-Amino-1-(4-fluoro-3-(trifluoromethyl)phenyl)ethanone

Participants

Reaction Steps

Cool a solution of 2-bromo-1-(4-fluoro-3-(trifluoromethyl)phenyl)ethanone (93% pure by HPLC, 1000 g; 3.51 mol) and THF (5 L) to <5° C. in an ice bath. Add a solution of sodium azide (239 g; 3.68 mol, 1.05 eq) in water (800 mL) drop wise over one hour at <5° C. After stirring at <5° C. for one hour, separate and discard the aqueous layer. While still cold, add the organic layer slowly over 3 hours to a solution of triphenylphosphine (920.2 g, 3.51 mol, 1.0 eq), p-toluenesulfonic acid monohydrate (1335 g, 7.02 mol, 2.0 eq), and THF (5 L). Maintain the temperature at <15° C. throughout this addition and solids precipitate during the addition. Stir the reaction mixture at <20° C. for 2 hours and then filter the solid, wash with THF (3×2 L), and dry at 50° C. under vacuum to give 1167.4 g (85%, 92% corrected for starting material purity) of 2-amino-1-(4-fluoro-3-(trifluoromethyl)phenyl)ethanone, 4-methylbenzenesulfonate as a white crystalline solid. HRMS (ESI) m/z (M+H) 222.0531 calculated for C9H8F4NO 222.0537

Provenance & Evidence