Diethyl Ether → (3S,4R)-1-tert-butyl 3-ethyl 4-((R)-1-phenylethylamino)-piperidine-1,3-dicarboxylate

Temperature

0 °C

A 1L 3-neck round bottom flask equipped with a mechanical stirrer and addition funnel was charged with 252B (14.7 g, 39 mmol) and acetonitrile (200 mL) and acetic acid (100 mL). The solution was cooled to 0° C. and Na(OAc)3BH (33.3 g, 157 mmol) was added in three portions over 2 hours. The reaction was stirred for two hours at this temperature after the final addition. The mixture was then cooled to −10° C. and slowly quenched by addition of 1 N NaOH (100 mL), 4 N NaOH (100 mL), 6 N NaOH (100 mL) followed by 50% NaOH (50 mL). The reaction was warmed to room temperature and the layers were separated. The aqueous layer was extracted with CH2Cl2 (2×250 mL) and the combined organic layers were dried (Na2SO4), filtered and concentrated in vacuo. Purification by flash chromatography (10% to 30% EtOAc/hexane gradient) on silica gel afforded 6.0 g (yield: 41%) of Compound 252C.

1. additionaddition
2. temperatureThe mixture was then cooled to −10° C.
3. customslowly quenched by addition of 1 N NaOH (100 mL), 4 N NaOH (100 mL), 6 N NaOH (100 mL)
4. temperatureThe reaction was warmed to room temperature
5. customthe layers were separated
6. extractionThe aqueous layer was extracted with CH2Cl2 (2×250 mL)
7. dry with materialthe combined organic layers were dried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated in vacuo
10. customPurification by flash chromatography (10% to 30% EtOAc/hexane gradient) on silica gel

ORD record

ord-9c99c915f4d9400cbfea7dae50405705

Source dataset

uspto-grants-2007_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07297695B2