(2S)-5-{[(benzyloxy)carbonyl]amino}-2-{[(tert-butoxy)carbonyl]amino}pentanoic acid → (2S)-5-amino-2-{[(tert-butoxy)carbonyl]amino}pentanoic acid

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Reaction Steps

Boc-Orn--OH (0.51 g) (obtained by catalytically reducing Boc-Orn(Z)--OH in methanol in a stream of hydrogen using 10% Pd-carbon as a catalyst) was dissolved in DMF, and the solution was cooled with ice. TEA (0.61 ml) and PhCOONB (prepared from PhCOOH (0.30 g), HONB (0.47 g) and DCC (0.54 g)) were added thereto, followed by stirring overnight. The reaction solution was concentrated, and the residue was dissolved in AcOEt. The resulting solution was washed with 10% aqueous citric acid. After washing with water, the solution was dried with Na2SO4 and concentrated. Then, ether and dicyclohexylamine (438 μl) were added to the residue to separate out a precipitate, which was collected by filtration.

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