Reaction #1747828

Reaction equation

NaBH3CN

KBr

NaHCO3

acetic acid

hydrochloride

3-(1-Propyl-1,4,5,6-tetrahydro-pyridin-3-yl)-cyclohex-2-enone

→

3-(1-Propyl-piperidin-3-yl)-cyclohex-2-enone

Solvents

water

THF

Conditions

Workup

1. 1
   Temperaturemaintaining the temperature
2. 2
   workup.ADDITIONAfter the addition
3. 3
   Otherat rt
4. 4
   Otherovernight
5. 5
   Extractionfollowed by extraction with dichloromethane (5×50 mL)
6. 6
   DryingThe combined organic layers were dried (MgSO4)
7. 7
   Otherevaporated
8. 8
   OtherThe residue was purified by column chromatography (silica, dichloromethane/ethanol 20:1)
9. 9
   Otherto give a colorless oil which
10. 10
    OtherRecrystallisation from isoprylether
11. 11
    Othergave 4.2 g, 17.5 mmol (77%), mp 184-185° C

Procedure

3-(1-Propyl-1,4,5,6-tetrahydro-pyridin-3-yl)-cyclohex-2-enone (5.0 g, 22.8 mmol) (from b) above) was dissolved in THF (100 mL). At 0° C., acetic acid (1.38 mL, 22.8 mmol) was added followed by introduction of NaBH3CN (1.9 g, 30.0 mmol) in small portions maintaining the temperature. After the addition was complete the mixture was stirred for 1 h at this temperature and then at rt overnight. Work-up by addition of water (50 mL) and saturated aqueous NaHCO3 (50 mL) followed by extraction with dichloromethane (5×50 mL). The combined organic layers were dried (MgSO4) and evaporated. The residue was purified by column chromatography (silica, dichloromethane/ethanol 20:1) to give a colorless oil which was converted to the hydrochloride. Recrystallisation from isoprylether gave 4.2 g, 17.5 mmol (77%), mp 184-185° C. IR (KBr) 3396, 2941, 2469, 1667, 1455 cm−1; 1H-NMR (CDCl3) δ 5.83 (s, 1H), 3.85 (d, 2H), 2.29-2.56 (m, 7H), 1.23-2.17 (m, 10H), 0.88 (t, 3H) ppm; 13C-NMR (CDCl3) δ 198.4, 165.1, 123.4, 59.0, 55.6, 51.9, 41.6, 36.0, 27.3, 26.9, 22.8, 21.2, 17.6, 10.2 ppm; MS (EI) m/z 221 (M+).

Source