反应详情

A 250 mL three-necked flask was charged with magnesium turnings (2.88 g, 0.12 mol) and a small crystal of iodine in THF (20 mL). The flask was evacuated and refilled with N2. A solution of 1-chloro-4-methoxybutane (15 g, 0.12 mol) in THF (40 mL) was added dropwise to the above mixture. After heating under reflux for 1 h, most of the magnesium had been consumed and the reaction mixture cooled to rt. Another 250-mL, three-necked flask was charged with (R)-3-(3-chloro-benzoyl)-piperidine-1-carboxylic acid tert-butyl ester (3.24 g, 10 mmol) and THF (50 mL), which was evacuated and refilled with N2. The mixture was cooled in a dry ice-acetone bath and the Grignard reagent derived from 1-chloro-4-methoxybutane (20 mL) was added dropwise. After addition, the mixture was allowed to warm slowly to rt and stirred for 2 h. The mixture was quenched with satd aq NH4Cl (100 mL) and extracted with EtOAc (3×80 mL). The combined organic layers were washed with brine, dried over Na2SO4 and concentrated in vacuo. The residue was purified by flash column chromatography (10:90 EA/PE) to give (R)-tert-butyl 3-((S)-1-(3-chlorophenyl)-1-hydroxy-5-methoxypentyl)piperidine-1-carboxylate (3.0 g, 73%). 1H NMR (400 MHz, CDCl3): 1.45 (s, 9H), 1.52-1.58 (m, 3H), 1.75 (m, 1H); 1.92 (m, 2H), 2.52 (m, 2H), 3.25 (s, 3H), 3.27 (m, 2H), 3.95 (m, 1H), 4.35 (m, 1H), 7.20-7.26 (m, 3H), 7.36 (m, 1H). MS (E/Z): 412 (M+H+).

1. customThe flask was evacuated
2. additionrefilled with N2
3. temperatureAfter heating
4. customhad been consumed
5. customwas evacuated
6. additionrefilled with N2
7. temperatureThe mixture was cooled in a dry ice-acetone bath
8. additionwas added dropwise
9. additionAfter addition
10. temperatureto warm slowly to rt
11. customThe mixture was quenched with satd aq NH4Cl (100 mL)
12. extractionextracted with EtOAc (3×80 mL)
13. washThe combined organic layers were washed with brine
14. dry with materialdried over Na2SO4
15. concentrationconcentrated in vacuo
16. customThe residue was purified by flash column chromatography (10:90 EA/PE)