反应详情

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), to a solution of tert-butyl 3-fluoro-4-oxopiperidine-1-carboxylate (0.80 g, 3.68 mmol) in MeOH (10 mL) was added ammonium acetate (1.99 g, 25.80 mmol) and the resulting solution stirred at rt for 2 h. NaCNBH3 (0.29 g, 4.42 mmol) was then added and the solution stirred at rt overnight. The reaction mixture was concentrated to dryness and the organics extracted with EA from a 1% aq. solution of Na2CO3. The combined organic extracts were washed with brine, dried over MgSO4, filtered and concentrated under reduced pressure. The residue was purified with FC (CH2Cl2/MeOH, 9:1) to afford trans-tert-butyl 4-amino-3-fluoropiperidine-1-carboxylate and cis-tert-butyl 4-amino-3-fluoropiperidine-1-carboxylate both as colorless oils which solidified upon standing. LC-MS-conditions 08: tR=0.48 min; [M-CH3+H]+=204.25 and tR=0.46; [M+H]+=219.26; TLC: rf (CH2Cl2/MeOH, 9:1)=0.30 and 0.09.

1. stirringthe solution stirred at rt overnight
2. concentrationThe reaction mixture was concentrated to dryness
3. extractionthe organics extracted with EA from a 1% aq. solution of Na2CO3
4. washThe combined organic extracts were washed with brine
5. dry with materialdried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified with FC (CH2Cl2/MeOH, 9:1)