[NH2:1][CH2:2][CH2:3][C:4]([OH:6])=[O:5].[CH2:7]([N:14]=[C:15]=[O:16])[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1>ClCCl.O1CCCC1.C(OCC)(=O)C>[CH2:7]([NH:14][C:15](=[O:16])[NH:1][CH2:2][CH2:3][C:4]([OH:6])=[O:5])[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1To a solution of β-alanine 5.0 g (56 mmol) in dichloromethane 56 ml and tetrahydrofuran 56 ml was added benzyl isocyanate 6.6 ml (53 mmol) at 0° C. After stirring at room temperature overnight, the reaction mixture was diluted with ethyl acetate 200 ml and washed with water 200 ml and brine 200 ml. The residual solution was concentrated to about 100 ml in vacuo. To the mixture was added 1N sodium hydroxide solution 60 ml at 0° C. The aqueous phase was acidified with 3N HCl aq. 20 ml and then extracted with ethyl acetate 100 ml twice. The extract was washed with brine 50 ml and dried over magnesium sulfate and filtered. The filtrate was concentrated in vacuo. To the residue was added ether:n-hexane=1:1 30 ml and the precipitate was corrected by filtration to obtain the title compound 7.05 g (59%).
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