Unusual cytotoxicities of 5-(acylethynyl)-1-(2-hydroxyethoxy)methyluracils

5-(Acylethynyl)-1-(2-hydroxyethoxy)methyl uracils (2)-(6) were synthesised in excellent yields from 1-(2-acetoxyethoxy)methyl-5-iodouracil (7) utilising palladium-copper catalysed reactions. Compounds (2)-(5) were shown to be highly active against CCRF-CEM (IC50 0.6–1.6 μM) and L1210/0 cells (IC50 0.7–2.2 μM) in culture, and thus exhibit greater activity than their parent bases. 5-(Acylethynyl)-1-(2-hydroxyethoxy)methyluracils, synthesized in excellent yields from 1-(2-acetoxyethoxy)methyl-5-iodouracil through palladium-copper catalyzed reactions, were found to be highly active against CCRF-CEM and L1210/0 cells in culture. They were more potent than their parent bases.