Synthesis and biological properties of new α-methylene-γ-butyrolactones and α,β-unsaturated δ-lactones

The synthesis of a series of α-methylene-γ-butyrolactones (compounds 4a, 4b, 6–12, 16, 17) and α,β-unsaturated-δ-lactones (compounds 19−23, 25, 26) starting from 4,4-dimethyldihydrofuran-2,3-dione (1) has been described. Their chemical structures were assigned by spectroscopic evidence. These new compounds exhibited significantly different antiproliferative properties against cultured human tumor cell lines with their IC50 values ranging from 0.88 to > 20.00 μM.