Some Pd-catalyzed coupling reactions have been evaluated for the synthesis of 5-substituted cytosines. A large number of 5-arylcytosines were prepared in good yields by using 2,4-O,N-bis-trimethylsilyl-5-iodocytosine with various aryl tin compounds. The use of trimethylsilyl groups proved to be essential for the reaction, attempted coupling of 5-iodocytosine and 2-trimethylstannylthiazole was not successful. One convenient alternative, which unfortunately was not successful, would have been to reverse the coupling functionalities and couple commercial arylhalides with 5-trimethylstannyl- or 5-tributylstannyl-derivatives or the corresponding 2,4-O,N-bis-trialkylsilylcytosines.