1,4-Dibromo-2,2-diethoxy-3-butanone → HCID 178467676, compound

Reaction equation

[Br:1][CH2:2][C:3]([O:11][CH2:12][CH3:13])([O:8][CH2:9][CH3:10])[C:4](=O)[CH2:5]Br.[C:14]([NH:17][C:18]([NH2:20])=[S:19])(=[NH:16])[NH2:15]>O1CCCC1>[CH4:2].[NH:17]([C:18]1[S:19][CH:5]=[C:4]([C:3]([O:11][CH2:12][CH3:13])([O:8][CH2:9][CH3:10])[CH2:2][Br:1])[N:20]=1)[C:14]([NH2:16])=[NH:15]

Participants

Procedure

A mixture of 25.5 g (80 mmol) of 1,4-dibromo-2,2-diethoxy-3-butanone, 11.8 g (100 mmol) of N-amidinothiourea, and 150 ml of tetrahydrofuran was heated at reflux for 3 hours. The mixture was filtered to remove some insoluble solid, and the filtrate was concentrated. The residue was triturated with 200 ml of saturated sodium bicarbonate, then extracted four times with a total of 500 ml of ethyl acetate. The combined ethyl acetate extracts were dried over sodium sulfate, filtered and evaporated leaving a solid. Recrystallization from 250 ml of acetonitrile, after decolorization with charcoal, afforded 9.7 g (36%) of 2-guanidino-4-(2-bromo-1,1-diethoxyethyl)thiazole as a white solid, mp 157°-158°; calcd. for C10H17N4O2SBr: C, 35.62; H, 5.08; N, 16.61; Br, 23.69; S, 9.51; found: C, 35.60; H, 4.97; N, 16.99; Br, 23.75; S, 9.59.