Photolysis of 5-iodo-, 2-chloro-5-iodo-, and 2,4-dichloro-5-iodo-pyrimidine in solutions of heteroarenes (furan, thiophen, pyrrole, and 1-methylpyrrole) or benzene in acetonitrile affords conveniently and in high yield the corresponding 5-(2-heteroaryl)- and 5-(phenyl)-pyrimidines (1)â (3)(X = O, S, NH, NMe, or CH.dbd;CH). Only for those photolyses carried out in thiophen are small amounts of the 3-heteroaryl isomers formed. In contrast, photolysis of the relatively unstable 4-chloro-5-iodopyrimidine in solutions of the above heteroarenes or benzene in acetonitrile gives only low yields of the 4-chloro-5-substituted pyrimidines.