Benzyl chloroformate → N2-((1,1-Dimethylethoxy)carbonyl)-N5-((phenylmethoxy)carbonyl)-D-ornithine

Participants

Reaction Steps

To a solution of Boc-D-Orn-OH (0.50 g, 2.2 mmol) in aqueous NaOH (1M, 5 mL) at 0° C. was added benzyl chloroformate (0.37 mL, 2.6 mmol, 1.2 equiv) followed by aqueous NaOH (1M, 5 mL). After stirring for 2 hours at room temperature, the reaction mixture was poured to separatory funnel and extracted with ether. The aqueous layer was acidified to pH 3 with aqueous 10% citric acid and extracted with ethyl acetate. The combined organic layer was washed with brine, dried with Na2SO4, filtered and concentrated in vacuo to afford compound 3.2.1a (0.57 g, 72%) which was used for the next step without further purification. MS m/z (M+Na) 389.2. 1H NMR (400 MHz, DMSO-d6) 12.37 (br-s, 1H), 7.35-7.25 (m, 5H), 7.20 (t, J=5.31 Hz, 1H), 7.01 (d, J=8.02 Hz, 1H), 4.97 (s, 2H), 3.83-3.77 (m, 1H), 2.94 (dd, 2H), 1.67-1.56 (m, 1H), 1.53-1.37 (m, 3H), 1.34 (s, 9H).

Provenance & Evidence