Réaction #1772027

Équation de réaction

4-phenyl-4-hydroxypiperidine

(S)-1-phenylethyl 2-bromo-2-phenylacetate

triethylamine

→

title compound

Rendement 27.3%

(S)-1-Phenylethyl (R)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-2-phenylacetate

Rendement 27.3%

Solvants

ethyl acetate

THF

THF

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGThe mixture was stirred for 16 hours
2. 2
   Lavagewashed (H2O ×2, brine)
3. 3
   Séchagedried (MgSO4)
4. 4
   Filtrationfiltered
5. 5
   Concentrationconcentrated
6. 6
   AutreThe residue was purified on a silica gel column (0-60% ethyl acetate-hexane)
7. 7
   Autreto provide
8. 8
   workup.ADDITIONan approximately 2:1 mixture of diastereomers
9. 9
   AutreSeparation of these isomers
10. 10
    Autrefluid chromatography (Chiralcel OJ-H, 30×250 mm; 20% ethanol in CO2 at 35° C.)

Mode opératoire

To a solution of (S)-1-phenylethyl 2-bromo-2-phenylacetate (1.50 g, 4.70 mmol) in THF (25 mL) was added triethylamine (1.31 mL, 9.42 mmol), followed by tetrabutylammonium iodide (0.347 g, 0.94 mmol). The reaction mixture was stirred at room temperature for 5 minutes and then a solution of 4-phenyl-4-hydroxypiperidine (1.00 g, 5.64 mmol) in THF (5 mL) was added. The mixture was stirred for 16 hours and then it was diluted with ethyl acetate (100 mL), washed (H2O ×2, brine), dried (MgSO4), filtered and concentrated. The residue was purified on a silica gel column (0-60% ethyl acetate-hexane) to provide an approximately 2:1 mixture of diastereomers, as judged by 1H NMR. Separation of these isomers was performed using supercritical fluid chromatography (Chiralcel OJ-H, 30×250 mm; 20% ethanol in CO2 at 35° C.), to give first the (R)-isomer of the title compound (0.534 g, 27%) as a yellow oil and then the corresponding (S)-isomer (0.271 g, 14%), also as a yellow oil. (S,R)-isomer: 1H NMR (400 MHz, CD3OD) δ 7.55-7.47 (m, 4H), 7.44-7.25 (m, 10H), 7.25-7.17 (m, 1H), 5.88 (q, J=6.6 Hz, 1H), 4.12 (s, 1H), 2.82-2.72 (m, 1H), 2.64 (dt, J=11.1, 2.5 Hz, 1H), 2.58-2.52 (m, 1H), 2.40 (dt, J=11.1, 2.5 Hz, 1H), 2.20 (dt, J=12.1, 4.6 Hz, 1H), 2.10 (dt, J=12.1, 4.6 Hz, 1H), 1.72-1.57 (m, 2H), 1.53 (d, J=6.5 Hz, 3H). LCMS: Anal. Calcd. for C27H29NO3: 415. found: 416 (M+H)+; (S,S)-isomer: H1NMR (400 MHz, CD3OD) δ 7.55-7.48 (m, 2H), 7.45-7.39 (m, 2H), 7.38-7.30 (m, 5H), 7.25-7.13 (m, 4H), 7.08-7.00 (m, 2H), 5.88 (q, J=6.6 Hz, 1H), 4.12 (s, 1H), 2.95-2.85 (m, 1H), 2.68 (dt, J=11.1, 2.5 Hz, 1H), 2.57-2.52 (m, 1H), 2.42 (dt, J=11.1, 2.5 Hz, 1H), 2.25 (dt, J=12.1, 4.6 Hz, 1H), 2.12 (dt, J=12.1, 4.6 Hz, 1H), 1.73 (dd, J=13.6, 3.0 Hz, 1H), 1.64 (dd, J=13.6, 3.0 Hz, 1H), 1.40 (d, J=6.6 Hz, 3H). LCMS: Anal. Calcd. for C27H29NO3: 415. found: 416 (M+H)+.

Source