Diisopropylethylamine → Tert-butyl 1-(3-bromo-5-fluoropyridin-4-yl)piperidine-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

A thoroughly stirred mixture of 3-bromo-4-chloro-5-fluoropyridine free base (55 g, 0.26 mol), potassium fluoride (31 g, 0.53 mol) and Me4NCl (5.8 g, 53 mmol) in DMSO (400 mL) was heated to 130° C. for 2 hours. The reaction mixture was cooled to room temperature and tert-butyl piperidine-4-carboxylate hydrochloride 22 (66 g, 0.30 mol) and DIPEA (65 g, 0.50 mol) were added. The reaction mixture was stirred at room temperature overnight. The solvent was evaporated in vacuo. The residue was portioned between DCM/water. The organic layer was washed with water (3×), dried over Na2SO4, and filtered over silica gel using DCM as eluent. The filtrated was evaporated to give tert-butyl 1-(3-bromo-5-fluoropyridin-4-yl)piperidine-4-carboxylate 26 (61 g, 65%) as a light yellow solid; 1H NMR (500 MHz, DMSO-d6) δ 8.47 (s, 1H), 8.41 (d, 1H), 3.39-3.36 (m, 2H), 3.12 (tt, 2H), 2.49-2.43 (m, 1H), 1.91-1.87 (m, 2H), 1.71-1.64 (m, 2H) and 1.43 (s, 9H); 19F NMR (500 MHz, DMSO-d6) δ −135.2; MS (ES+) 361.0.

Provenance & Evidence