Abstract: Asimple approach to highly stereoselective synthesis of trans-β-methoxycarbonyl γ-aryl-γ-butyrolactones(5a—5c) is reported. Methoxycarbonylmethyltriphenylarsonium bromide(1) in dimethyl ethylene glycol was reacted with 2,2-dimethyl-1,3-dioxa-5-p-methoxybenzal-4,6-dione(2a) in the presence of K₂CO₃ and trace of water at room temperature, to give trans-β-methoxycarbonyl-γ-p-methoxyphenyl-γ-butyrolactone(5a) with 64% yield, whereas 1,2-cis cyclopropane derivatives(3b and 3c) were isolated when started from 2b or 2c, under same conditions. The γ-butyrolactones 5b or 5c were obtained with 62% and 57% yields when compounds 3b or 3c was further heated in acetone water. The structures of 5a—5c were established on the basis of IR, ¹Hand ¹³ C NMR, MSand elemental analyses, and their configurations were assigned via 2Dproton NOESYspectrum of compound 5c.

Key words: Arsenic ylide, Stereoselective synthesis, γ-Butyrolactone