Synthesis of various 5‐arylsubstituted cytosines

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.