Combine (S)-N-(2-methoxybenzyl)-N-methyl-2-[N'-(t-butoxycarbonyl)-allylamino]-3-phenyl-propionamide (0.66 g, 1.52 mmol), N-methylmorpholine-N-oxide (0.20 g, 1.67 mmol), acetone (5 mL), and water (5 mL). Add osmium tetraoxide (0.78 mL, 0.04M in THF, 0.032 mmol) and stir under an inert atmosphere for 18 hours. Pour the reaction mixture into a saturated solution of sodium bisulfite and extract the intermediate diol into ethyl acetate. Dry the separated organic layer over MgSO4, filter, and evaporate in vacuo to give the crude diol which is used without further purification. Dissolve the crude diol in chloroform (10 mL). Add a solution of lead tetraacetate (0.74 g, 1.67 mmol) in chloroform (10 mL). Stir for 30 minutes and then pour the reaction mixture into a saturated solution of sodium bicarbonate. Extract with dichloromethane and separate the organic layer. Dry the separated organic layer over MgSO4, filter and evaporate in vacuo to give the title compound which may be used without further purification.
