Toluene → 1-Piperidinecarboxylic acid, 3-[(R)-(3-chlorophenyl)hydroxymethyl]-, 1,1-dimethylethyl ester, (3R)-

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Reaction Conditions

Reaction Steps

To a solution of (R)-tert-butyl 3-(3-chlorobenzoyl)piperidine-1-carboxylate (92 g, 0.286 mol) in anhydrous THF (300 mL) at −15° C. under nitrogen was added drop wise a solution of 1 M R-CBS-oxazaborolidine in toluene (45 mL, 45 mmol, 0.15 eq). After stirring for 1 hr at −15° C., a solution of 10 M BH3 in THF (33 mL, 0.33 mol, 1.1 eq) was added drop wise. After addition, the reaction mixture was stirred for 2 h at −15° C. TLC indicated the starting material was consumed. Methanol (200 mL) was added drop wise carefully at −15° C. The solvent was removed under reduced pressure, the residue was purified by column chromatography on silica gel eluting with AcOEt/hexane (1:30→1:15) to provide a light yellow oil (82 g, HPLC≧70%, ratio≧3:1). The mixture was dissolved in ethyl acetate until the alcohol was just dissolved (about 5 mL/1 g), the solvent was removed on the rotary evaporator until a few of crystals appeared. The solution was cooled to room temperature slowly and stood for 1-2 h. To the above solution was added hexane (about 300 mL) and then filtered, the crystals were washed with cool hexane and recrystallized another two times to afford (R)-tert-butyl 3-((R)-(3-chlorophenyl)(hydroxy)methyl)piperidine-1-carboxylate as the pure isomer (32.5 g, ee.≧99%, yield 35% for two steps).

Provenance & Evidence