(E)-4-(Benzo[d][1',3']-dioxol-5'-yl)-but-3-en-2-one was reduced with NaBH4 in MeOH at 0 degrees C to resp. alc. converted then to Et(E)-(benzo[d][1',3']-dioxol-5'-yl)-hex-4-enoate with MeC(OEt)(3) in presence of EtCOOH at 138-140 degrees C. The ester was then lactonized in CHCl3 with m-ClC6H4COOH in presence of CF3COOH at room temp. to a mixt. of trans-4-(benzo[d][1',3']-dioxol-5'-yl)-5-(1-hydroxyethyl)-dihydrofuran-2-one (yield 8%) and 4-r-(benzo[d][1',3']-dioxol-5'-yl)-5-c-hydroxy-6-t-methyltetrahydropyran-2-one (yield 0.2%). Similarly, Et(E)-3-phenylhex-4-enoate, (E)-3-(p-methylphenyl) hex-4-enoate and (E)-3-(p-methoxyphenyl)hexen-4-enoate were converted to resp. dihydrofuranones (yields 9%, 8% and 10%, resp.), tetrahydropyranones (yields 0.3%, 0.4% and 0.3%, resp.). The dihydrofuranones were studied for antifeedant and antiproliferative activity and biolog. tests. The compds. with Ph and p-MeC6H4 substituents showed good deterrent activity towards storage insect pests. The compds. substituted with O-contg. benzene rings had noticeable antiproliferative activity towards human osteosarcoma cell line.