Lithium Hydroxide → 4-(3,3-Difluoropiperidin-1-yl)-3-nitrobenzoic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of ethyl 4-fluoro-3-nitrobenzoate (Chontech 01072; 500 mg; 2.35 mmol; 1 eq.), 3,3-difluoropiperidine hydrochloride (Aldrich 665517; 554.47 mg; 3.52 mmol; 1.5 eq.) and triethylamine (712.07 mg; 7.04 mmol; 3 eq.) in DMF (3 mL) was stirred at 60° C. for 4 hours. The reaction mixture was then partitioned between ethyl acetate and aq. NH4Cl. The organic layer was washed three times with aq. NH4Cl then brine, dried over magnesium sulfate and concentrated in vacuo to give a yellow oil. The oil was taken up in THF (15 mL) and lithium hydroxide (280.86 mg; 11.73 mmol; 5 eq.) then water (15 mL) were added. The reaction mixture was stirred at room temperature for 4 hours and the THF was evaporated under vacuum. The resulting solution was washed with Et2O, acidified with acetic acid and extracted twice with Et2O. The combined organic layer was dried over magnesium sulfate and concentrated in vacuo to give a yellow oil which was crystallized from water. Filtration and drying under high vacuum afforded the title compound (630 mg, 94%) as a yellow solid.

Provenance & Evidence