The convenient synthesis of hydrogen-bonded ureidopyrimidinones

Blocked isocytosine isocyanates are conveniently obtained by the reaction of 1,1'-carbonyldiimidazole (CDI) with isocytosines. The resulting precursors for quadruple hydrogen-bonded structures can be isolated and stored for further use. Reaction with either aliphatic or aromatic amines gives the corresponding mono-, bi-, or trifunctional ureidopyrimidinone derivatives in good to excellent isolated yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).