Synthesis of unsymmetrical urea derivatives one-pot sequential three-component reactions of cyclic 2-diazo-1,3-diketones, carbodiimides, and 1,2-dihaloethanes

A novel and efficient multicomponent reaction of cyclic 2-diazo-1,3-diketones, carbodiimides, and 1,2-dihaloethanes has been developed, and it leads to unsymmetrical urea derivatives with good yields in a single operation. This transformation involves the cascade formation of C-X (X = Cl, Br, I), C-N and C&z.dbd;O bonds through halogenation, nucleophilic addition, ring-opening, and enol-ketone tautomerization processes. This protocol is step- and atom-economical; 1,2-dihaloethane was used as an easily available halogenated reagent, and it is amenable to different functional groups. An effective and operationally simple one-pot strategy has been developed for the synthesis of unsymmetrical urea derivatives via sequential three-component reactions of cyclic 2-dizao-1,3-diketones with carbodiimides and 1,2-dihaloethane.