A series of 5-aryl-3-alkylidenedihydrofuran-2(3H)-ones 6a-g'' and 11a,b as well as 5-aryl-3-methylidenepyrrolidin-2-ones 10a-c and 12 were synthesized starting from 4-aryl-2-diethoxyphosphoryl-4-oxobutanoates 3a-g. Reaction sequence includes reduction or reductive amination of the carbonyl group, lactonization or lactamization step and finally the Horner-Wadsworth-Emmons olefination of aldehydes using thus obtained 5-aryl-3-diethoxyphosphoryl-3,4-dihydrofuran-2(5H)-ones 5a-g'' or 5-aryl-3-diethoxyphosphorylpyrrolidin-2-ones 9a-c. Furanones 6 and 11, as well as pyrrolidinones 10 and 12, were evaluated in vitro against mouse leukemia cell line L-1210 and two human leukemia cell lines HL-60 and NALM-6. Several of the obtained furanones proved to be very potent against all three cell lines with IC(50) values lower than 6 microM. Structure-activity relationships of these compounds, as well as 5-alkyl or 5-arylmethyl-3-methylidenedihydrofuran-2(3H)-ones 13a-e, previously obtained in our laboratory, are discussed.