Sodium Hydroxide → tert-Butyl (2S)-5-{[(benzyloxy)carbonyl]amino}-2-{[(tert-butoxy)carbonyl]amino}pentanoate

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Reaction Steps

Dissolve N5 -benzyloxycarbonyl-ornithine, t-butyl ester (3.22 g, 10 mmol) in 50/50 dioxane/water (25 mL) and buffer to pH 10 with 1N sodium hydroxide. Add, by dropwise addition, an ether solution of t-butyl azidoformate (1.58 g, 11 mmol) at 10° C. Allow to warm to room temperature and buffer occasionally to retain pH 10. Acidify with a sodium citrate/citric acid buffer to pH 5, extract with ether (3×), dry (MgSO4) and blow to a residue with a stream of nitrogen to give N-t-butyloxycarbonyl-N5 -benzyloxycarbonyl-ornithine, t-butyl ester.

Provenance & Evidence