4-Methyl-2-(methylthio)pyrimidine is used as a reagent to prepare pyrazolopyrimidines and pyrazolotriazines, both of which display potent activity against herpes viruses. 4-Methyl-2-(methylthio)pyrimidine is also used as a starting material to synthesize 4-substituted-2-aminopyrimidines (e.g. 2-amino-4-ethylpyridine [A609500]), novel c-Jun N-terminal kinase (JNK) inhibitors.