Water → 1-Methyl-3-(4-cyano-3-(dipropylamino)-5-isothiazolyl)urea

Participants

Reaction Steps

A solution of 7.0 g of 5-amino-4-cyano-3-(dipropylamino)isothiazole, 3.6 g of methyl isocyanate and 40 drops of dibutyltin diacetate in 50 ml of tetrahydrofuran was heated under reflux overnight. Thin-layer chromatographic analysis indicated the reaction to be complete. The reaction mixture was poured into rapidly stirred, cold water. The solid precipitate was collected by filtration. The filtrate was extracted with methylene chloride. The solid was combined with the extract and the mixture dried over calcium chloride, then filtered through magnesium sulfate. The filtrate was concentrated under reduced pressure and the residue was taken up in a mixture of toluene and benzene to which a little ethanol had been added. Pentane was then added to promote crystallization. The recrystallization yielded 6.2 g of 1-methyl-3-(4-cyano-3-(dipropylamino)-5-isothiazolyl)urea, m.p. 179°-180°. The nmr and ir spectra were consistent with the assigned structure.

Provenance & Evidence