[NH:1]([CH:5]([CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][CH2:16][C:17]([O:19][CH2:20][CH3:21])=[O:18])[C:6](OCC)=[O:7])[C:2]([NH2:4])=[O:3].C1(C2CCCCCCCC=2)CCCCCCNN=1.C(Cl)(Cl)Cl.Cl>CCOCC>[CH2:20]([O:19][C:17]([CH2:16][CH2:15][CH2:14][CH2:13][CH2:12][CH2:11][CH:5]1[NH:1][C:2](=[O:3])[NH:4][C:6]1=[O:7])=[O:18])[CH3:21]A mixture of diethyl 2-ureidononanedioate (8 g) with diazabicyclononene (DBN) (1.28 g) was heated in a bath at 100° for 1 hour and the reaction mixture was shaken with chloroform and a slight excess of dilute hydrochloric acid. The chloroform phase was separated, washed with water and dried (MgSO4), and the chloroform was evaporated, to give a crystalline residue. The crystals were suspended in ether and collected, to give 5-(6-ethoxycarbonylhexyl) hydantoin, m.p. 110°-110.5° C.
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