One-Step Synthesis of Highly Functionalized Monofluorinated Cyclopropanes from Electron-Deficient Alkenes
摘要:
The unique combination of Zn/LiCl allowed generation of reactive zinc enolate from ethyl dibromofluoroacetate. This fluorinated enolate reacts efficiently with a wide range of functionalized electron-deficient alkenes to afford the corresponding monofluorinated cyclopropylcarboxylates in good yields.
New chiral fluorinated reagents (N-(dibromofluoroacetyl)oxazolidinones) were easily synthesized and used in an asymmetric cyclopropanation process. The Michael initiated ringclosurereaction provided chiral cyclopropanes bearing a fluorinated quaternary stereocenter. Various electron-deficient alkenes can be used to efficiently obtain chiral polysubtituted fluorinated cyclopropanes in good yields