t-Butyllithium and t- butylmagnesium chloride cyanocuprates were used to prepare 4(6)-t- butylpyrimidines from the corresponding 4(6)-halopyrimidines . The highly hindered 2,4,5-tri-t-butyl-6-chloropyrimidine, containing an ortho-di-t-butyl arrangement, was prepared by this method. No alkyl group isomerization was observed but some substrate reduction was detected.