反应详情

A 10 mL round-bottomed flask was charged with a solution of 3-oxoazetidine-1-carboxylic acid tert-butyl ester (1 g, 5.84 mmol), 4-fluoropiperidine hydrochloride (0.97 g, 6.42 mmol) and 4 Å molecular sieves (10 g) in DCE (50 mL). The reaction mixture was stirred for 4 h at room temperature. Sodium triacetoxyborohydride (2.48 g, 11.68 mmol) was added and the reaction mixture was stirred for 18 h at room temperature. The suspension was filtered through Celite and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography (Si—PPC, EtOAc:cyclohexane, gradient 0:100 to 100:0) then (Si—PPC, MeOH:DCM, 0:100 to 5:95) to give 3-(4-Fluoropiperidin-1-yl)azetidine-1-carboxylic acid tert-butyl ester as a colourless oil (0.59 g, 39%). 1H NMR (CDCl3, 400 MHz) δ 4.80-4.58 (m, 1 H); 3.97-3.89 (m, 2 H); 3.85-3.76 (m, 2 H); 3.08 (t, J=6.4 Hz, 1 H); 2.50-2.28 (m, 4 H); 1.99-1.82 (m, 4 H); 1.48-1.38 (m, 9 H).

1. stirringthe reaction mixture was stirred for 18 h at room temperature
2. filtrationThe suspension was filtered through Celite
3. concentrationthe filtrate was concentrated in vacuo
4. customThe residue was purified by flash chromatography (Si—PPC, EtOAc:cyclohexane, gradient 0:100 to 100:0)