Reaction #1135

Reaction equation

pyridine

trifluoroacetic acid

→

5-(4-fluorophenyl)-3-(2-piperidinyl)pyridine

Solvents

dichloromethane

Conditions

Workup

1. 1
   OtherThe solvents were removed in vacuo
2. 2
   workup.DISSOLUTIONthe crude material dissolved in ethyl acetate (50 mL)
3. 3
   workup.ADDITIONSaturated sodium carbonate solution (30 mL) was added
4. 4
   Otherthe organic layer separated
5. 5
   ExtractionThe aqueous phase was extracted with two further portions of ethyl acetate (2×30 mL)
6. 6
   Washthe combined organic extracts washed with brine (20 mL)
7. 7
   Dryingdried (Na2SO4)
8. 8
   Concentrationconcentrated in vacuo
9. 9
   OtherThe residue was chromatographed on silica gel with ethyl acetate

Procedure

The above-described pyridine derivative (1.25 g, 3.5 mmol) was dissolved in a mixture of dichloromethane (10 mL) and trifluoroacetic acid (10 mL) and this was stirred at 25° C. for 18 h. The solvents were removed in vacuo and the crude material dissolved in ethyl acetate (50 mL). Saturated sodium carbonate solution (30 mL) was added and the organic layer separated. The aqueous phase was extracted with two further portions of ethyl acetate (2×30 mL), the combined organic extracts washed with brine (20 mL), dried (Na2SO4) and concentrated in vacuo. The residue was chromatographed on silica gel with ethyl acetate, then methanol:ethyl acetate (1:9) as eluant to afford 5-(4-fluorophenyl)-3-(2-piperidinyl)pyridine, 940 mg, 100%. NMR (CDCl3, 300 MHz): δ 8.69 (d, J=2 Hz, 1 H), 8.55 (d, J=2 Hz, 1 H), 7.93 (t, J=2 Hz, 1 H), 7.56 (m, 2 H), 7.16 (app. tm, J=9 Hz, 2 H), 3.18 (d, J=12 Hz, 1 H), 2.83 (td, J=12, 3 Hz, 1 H), 2.61 (bs exch., 1 H), 1.92 (m, 2 H), 1.45-1.75 (m, 6 H).

Source