Styrene → [(R)-1-(4-benzyloxy-2-methoxy-phenyl)-2-hydroxy-ethyl]-carbamic acid tert-butyl ester

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Reaction Steps

To 569 mg (4.86 mmol) of t-butylcarbamate suspended in 6.3 ml n-propanol was added 4.8 ml 1 N NaOH (4.8 mmol), and freshly prepared tBuOCl (548 ul, 4.8 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 (73.2 mg, 0.094 mmol) dissolved in 6.3 ml n-PrOH. This was followed by the addition of the styrene (307 mg, 1.28 mmol) also dissolved in 11 ml n-PrOH, and stirred for another 8 min. Then K2OsO4.2H2O (23 mg, 0.063 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 on the ISCO using 5-50% EtOAc/hex to obtain 146 mg (30%) of the titled compound.

Provenance & Evidence