Allylic Alkylation And Electrophilic Fluorination Reaction Of Pyrazolin-5-ones With MBH Carbonates

Pyrazolone derivatives, an important class of aza-heterocycles, are very usefulcompounds serving as building blocks for the synthesis of natural products, medicines,and agrochemicals. Based on the theory of fluorine chemistry, the introduction offluorine atom into pyrazolone molecules may significantly impact thephysicochemical properties of these compounds. However, the use and preparation offluorinated pyrazolones is extremely rare. Therefore, development of rapid andefficient methods for the synthesis of fluorinated pyrazolones is still in great demand.As multifunctional compounds, MBH carbonates have been widely used in organicsynthesis. Functional group transformation of MBH carbonates has been extensivelystudied in the past decades, especially for its organocatalytic asymmetric allylicalkylation reactions with a wide range of nucleophiles.In this thesis, we developed a DABCO-mediated one-pot sequential transformationof pyrazolones with Morita-Baylis-Hillman (MBH) carbonates andN-fluoro-N-(phenylsulfonyl) benzenesulfonamide (NFSI) via allylic alkylation/electrophilic fluorination. By using this process, a series of fluorinatedpyrazolin-5-ones were synthesized in moderate to high yields (40–83%) with up to85:15dr under mild conditions. Further extension of this one-pot sequential reactionto other halogenating reagents, such as NBS and NCS, also proved effective.Additionally, other fluorinated pyrazolin-5-one derivatives have been obtained underchanging conditions.