Anions derived from t-butyl-substituted pyrimidin-4-ols were methylated with iodomethane . The site of methylation was determined by proton-coupled 13C n.m.r. and the relative proportions of isomers were determined by 1H n.m.r. A t-butyl substituent ortho to a ring nitrogen markedly reduced the propensity for methylation at that nitrogen to the point where O-methylation, uncommon under these conditions, was observed.
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.