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

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Reaction Steps

To 15.36 g (131.1 mmol) of tert-butoxycarbamate suspended in 100 mL propanol was added 150 mL 0.87 M NaOH (131.1 mmol), and freshly prepared tBuOCl (14.9 g 131.1 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 (2.0 g, 2.59 mmol) dissolved in 30 mL PrOH. This was followed by the addition of the styrene (9.64 g, 42.99 mmol) also dissolved in 20 mL PrOH, and stirred for another 8 min. Then K2OsO4.2H2O 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 8.5 g (55%) of the product.

Provenance & Evidence