A general and practical method for the preparation of unsymmetrically substituted ureas has been developed. By the reactions of acetoacetanilides with various amines including primary/secondary amines, a series of substituted aryl ureas were achieved in high yields. Acetoacetanilide substrates can be considered as masked reagents that liberate reactive isocyanates in situ.
Iron(II)-Catalyzed Oxidation of sp<sup>3</sup> C−H Bonds Adjacent to a Nitrogen Atom of Unprotected Arylureas with <i>tert</i>-Butyl Hydroperoxide in Water
With a FeSO4/TBHP system in water, direct oxidation of sp3 C−Hbondsadjacent to nitrogen of arylureas to give both unprecedented tert-butoxylated and hydroxylated products 2 was revealed. Under elevated temperatures, either 2-oxo-N-arylpyrrolidine-1-carboxamides 3 or 1,3-diarylureas 4 were attained, depending on the aliphatic ring size of the arylurea substrates.