Cbz-L-methionine methyl ester → Methyl (2S)-4-(methylsulfinyl)-2-[[(phenylmethoxy)carbonyl]amino]butanoate

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Reaction Steps

Sulfide 59 (5.40 g, 18.2 mmol) was dissolved in methanol (60 mL). This was cooled in ice and a solution of sodium metaperiodate (4.08 g, 1.05 equiv) in water (25 mL) was added dropwise over 10 mins. This was stirred in ice for 1 h and then at rt for a further 2 h. The resultant white precipitate was removed by filtration under vacuum, the residue washed with methanol and the filtrate concentrated in vacuo. The resultant colourless oil was partitioned between DCM and water. The aqueous phase was extracted twice more with DCM, methanol added to the combined organic extracts to obtain an homogenous solution and this was dried (MgSO4), filtered and concentrated in vacuo to afford a yellow oil, 5.69 g, 100%. This was obtained as a 1:1 mixture of diastereoisomers.

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