In this work the alkylation of 2-ethylsulfanyl -5-methoxy-4(3H)-pyrimidinone with 4-substituted ω-bromoacetophenones, ethyl 2-bromoalkanoates and 1-bromomethyl-o-carborane was investigated. It was found that reaction of title compounds in the presence of potassium carbonate in boiling acetonitrile yielded O-alkylated derivatives with small amount of N3- and N1-alkylation products. The proportion of O- and N-alkylated products varied depending on the nature of substituent in the 4th position of benzene ring. Alkylation of title compound with ethyl bromoethanoate led to mixture of O-, N3- and N1 alkylated derivatives, while the reaction with ethyl 2-bromopropanoate yielded only O-alkylated isomer. 2-Substituted 4-pyrimidinols with nido-carborane at the side chain were synthesized. The structure of synthesized compounds was confirmed by the data of IR, UV and 1H NMR spectra.