Synthetic routes are described for 5-phenyl-, 5-p-chlorophenyl-, 2-p-tolyl-, 2- and 4-benzyl- and 4-phenoxy-pyrimidines, each bearing a sulfur-, nitrogen- or oxygen-linked basic side chain; also to analogous biphenyls and a diphenylmethane . These compounds were required for evaluation as amplifiers of phleomycin.