Accumulating　evidence　demonstrates　that　mifepristone　(RU486)　exhibits　potent　anti-proliferative　effects　on　various　cancer　cell　lines.　Our　recent　work　shows　that　its　major　metabolite　metapristone　(RU42633)　is　a　good　drug　candidate　for　cancer　metastatic　chemoprevention.　However,　lack　of　an　efficient　method　for　synthesizing　metapristone　limited　its　further　clinical　development.　Herein,　an　improved　and　efficient　condition　of　N-demethylation　of　mifepristone　with　an　excellent　yield　is　described.　The　procedure　presented　here　has　several　advantages　including　one-pot　preparation,　ease　of　synthesis,　and　large-scale　feasibility.