1-Propanol → [(R)-2-Hydroxy-1-(4-methoxy-phenyl)-ethyl]-carbamic acid benzyl ester

참여 물질

반응 단계

To 1.88 g (12.4 mmol) of benzylcarbamate suspended in 16 mL n-propanol was added 12.2 mL 1 N NaOH (12.2 mmol), and freshly prepared tBuOCl (1.4 mL, 12.2 mmol) and then stirred for 8 min at rt. It was then cooled to 0° C. followed by the addition of the catalyst (DHQD)2PHAL (156 mg, 0.2 mmol) dissolved in 14 mL n-PrOH. This was followed by the addition of the styrene (538 uL, 4 mmol) also dissolved in 20 mL n-PrOH, and stirred for another 8 min. Then K2OsO4.2H2O (58.8 mg, 0.16 mmol) was added directly, and the resulting mixture stirred for 1.5 hr at 0° C. Several color changes were observed, from brown, to bright red, to orange and then finally light yellow. Dilute with EtOAc, and quench with aq. Na2S2O3. The organic layer was separated and the aqueous layer extracted with EtOAc. The combined organic layers were washed with brine, dried over MgSO4, and concentrated. It was purified by flash column 20-40% EtOAc/hexanes to obtain 761 mg (63%) of the product.

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