Reaction #1140

Reaction equation

5-bromo-3-(3,3-dibromo-1-methyl-5-pyrrolidin-2-onyl)pyridine

tellurium

Sodium borohydride

ethyl acetate

→

5-bromo-3-(1-methyl-5-pyrrolidin-2-onyl)pyridine

Yield 68.0%

Solvents

ethanol

Conditions

Workup

1. 1
   TemperatureThe mixture was heated
2. 2
   Temperatureunder reflux for 0.25 h
3. 3
   Filtrationthe solution was filtered through Celite
4. 4
   Concentrationconcentrated in vacuo
5. 5
   workup.ADDITION1M HCl (10 mL) was added to the residue
6. 6
   ExtractionAfter extraction with ethyl acetate (50 mL) the organic phase
7. 7
   Otherwas separated
8. 8
   ExtractionThe aqueous phase was extracted with ethyl acetate (2×50 mL)
9. 9
   Washthe combined organic phases were washed with brine (30 mL)
10. 10
    Dryingdried (MgSO4)
11. 11
    Concentrationconcentrated
12. 12
    OtherThis material was chromatographed on silica gel with ethyl acetate:hexane (1:1) as eluant

Procedure

Sodium borohydride (862 mg, 22.8 mmol) was dissolved in ethanol (20 mL) and tellurium metal powder (1.45 g, 11.4 mmol) was added in portions. The mixture was heated under reflux for 0.25 h and 5-bromo-3-(3,3-dibromo-1-methyl-5-pyrrolidin-2-onyl)pyridine (775 mg, 1.9 mmol) was added to the solution at 25° C. After stirring for 2 h, ethyl acetate (50 mL) was added and the solution was filtered through Celite and concentrated in vacuo. 1M HCl (10 mL) was added to the residue and the solution was adjusted to pH 11 with solid potassium carbonate. After extraction with ethyl acetate (50 mL) the organic phase was separated. The aqueous phase was extracted with ethyl acetate (2×50 mL) and the combined organic phases were washed with brine (30 mL), dried (MgSO4) and concentrated. This material was chromatographed on silica gel with ethyl acetate:hexane (1:1) as eluant to afford 5-bromo-3-(1-methyl-5-pyrrolidin-2-onyl)pyridine as a solid (329 mg, 68%). M.p. 85°-87° C.; 1H NMR (CDCl3, 300 MHz): δ 8.66 (d, J=2 Hz, 1H), 8.42 (d, J=2 Hz, 1H), 7.68 (t, J=2 Hz, 1H), 4.56 (t, J=7 Hz, 1H), 2.71 (s, 3H), 2.45-2.65 (m, 2H), 1.80-1.95 (m, 2H).

Source