Synthesis and cytotoxic evaluation of β-alkyl or β-aryl-δ-methyl-α-methylene-δ-lactones. Comparison with the corresponding γ-lactones

We present a simple and general strategy for the synthesis of β,δ-disubstituted-α-methylene-δ-lactones starting from easily available tert-butyl 2-(diethoxyphosphoryl)alk-2-enoates. The elaborated synthetic protocol includes pyrrolidine-catalyzed Michael addition of acetone, diastereoselective reduction of the carbonyl group, lactonization and finally the Horner–Wadsworth–Emmons reaction with formaldehyde. All α-methylene-δ-lactones were evaluated in vitro against mouse leukemia cell line L-1210 and two human leukemia cell lines HL-60 and NALM-6. Comparison of cytotoxic activity with corresponding α-methylene-γ-lactones is also discussed.

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