Various (E)-β-(pyrimidin-5-yl) acrylamides (4 and 5) were synthesized as sparsomycin analogs, and the relationship between chemical structure and antitumor activity was examined.Synthesis involved condensation of appropriate acids (3) and methyl methioninate (L and D isomers) by the mixed anhydride method using isobutyl chlorocarbonate.The antitumor activity was studied by [methyl-3H] thymidine incorporation assay with mouse leukemia L5178Y cells in vitro.The concentrations in μg/ml required for 50% inhibition of incorporation by compounds 4b, 4f, g, 5b, and 5f, g, which have no substituent at the 2 or 6 position on pyrimidine ring, were particularly high. Thus, such substituents enhanced antitumor activity, although the activity was almost uninfluenced by changes of the alkoxy group as a substituent.