In this paper, we report the tandem Michael addition-elimination reactions of chiral 5-alkoxy-3,4-dihalo-2(5H)-furanones with DMF by the catalyst of metal sodium. The optically pure 5-(S)-alkoxy-4-N,N-dimethyl-3-halo-2(5H)-furanones 6a6d were identified on the basis of their analytical data, such as [α]20D , UV, IR, 1H NMR, 13C NMR, MS and elemental analysis.