反应详情

温度

0 °C

To a clear colorless solution of (R)-3-(dibenzylamino)cyclohexanone (5.697 g, 19.42 mmol) in dry diethyl ether (300 mL) was added a solution of 3 M methylmagnesium bromide (8.09 mL, 24.27 mmol) dropwise slowly at 0° C. The reaction mixture was stirred at 0° C. for 15 min and the ice-bath was then removed. The reaction mixture was stirred at room temperature for 2 h. Upon completion of the reaction, as indicated by LCMS and TLC, the cloudy solution was slowly poured into a saturated aqueous solution of ammonium chloride (250 mL). The ether layer was separated, and the aqueous layer was re-extracted with ether (250 mL). The combined ether layers were dried over magnesium sulfate concentrated and purified by silica gel chromatography (0%-80% ethyl acetate in hexanes) to yield two diastereomeric isomers of (3R)-3-(dibenzylamino)-1-methylcyclohexanol (isomer I and isomer 2). Isomer 1 (2.704 g, 45%) was obtained as a white solid and isomer 2 (1.866 g, 31%) as a colorless oil, which still contained a small amount of impurities. Isomer 2 was used without further purification in the next step.

1. customthe ice-bath was then removed
2. stirringThe reaction mixture was stirred at room temperature for 2 h
3. customUpon completion of the reaction
4. customThe ether layer was separated
5. extractionthe aqueous layer was re-extracted with ether (250 mL)
6. dry with materialThe combined ether layers were dried over magnesium sulfate
7. concentrationconcentrated
8. custompurified by silica gel chromatography (0%-80% ethyl acetate in hexanes)