DABCO-mediated one-pot sequential transformation: convenient access to fluorinated 1H-pyrazol-5(4H)-ones

A Lewis base-mediated one-pot sequential transformation of pyrazolones with Morita-Baylis-Hillman (MBH) carbonates and N-fluoro-N-(phenylsulfonyl)benzenesulfonamide (NFSI) has been developed. By using this process, a series of fluorinated pyrazolone derivatives have been synthesized in 40-83% yields.