An Efficient Synthesis of 1-Substituted Uracil Ring Systems and Their Thio Analogues

Abstract A facile and simple regioselective synthesis of uracils and their thio analogues has been achieved by cyclocondensation of a common precursor, diazadienium iodide 1, and isothiocyanates 2A,B. The key step in this synthetic process is the preparation of 4-methylsulfanylpyrimidine-2-thiones 3A,B, which after ­further elaboration gave the expected uracil analogues 4A,B-8A,B.