Trifluoroacetic acid → 1-(4-(2-fluoropyridin-3-yl)-5,6-dihydropyridin-1(2H)-yl)ethanone

Participants

Reaction Steps

A solution of tert-butyl 4-(2-fluoropyridin-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate (2.69 g, 9.67 mmol) in CH2Cl2 (8 mL) was added trifluoroacetic acid (7.45 mL, 97 mmol) and stirred at RT for 2 h. The reaction was concentrated in vacuo, and the residue was partitioned between CH2Cl2 and aqueous saturated NaHCO3 solution. The organic layer was dried (MgSO4), filtered, and concentrated in vacuo to give a golden yellow oil. A solution of the crude golden yellow oil in CH2Cl2 (10 mL) was cooled to 0° C. and added acetic anhydride (4.5 mL, 48.3 mmol). The reaction was gradually allowed to warm to RT and stirred for 16 h. The reaction was diluted with CH2Cl2 and washed with aqueous saturated NaHCO3 solution; the aqueous layer was back-extracted with CH2Cl2 (1×). The organic extracts were combined, dried (MgSO4), and concentrated in vacuo. Flash column chromatography (20% to 80% EtOAc/Hexanes) afforded 1-(4-(2-fluoropyridin-3-yl)-5,6-dihydropyridin-1(2H)-yl)ethanone as a colorless oil. [M+1]=221.1.

Provenance & Evidence