[2,3]-Wittig Rearrangements of Difluoroallylic Ethers. A Facile Entry to Highly Functionalized Molecules Containing a CF₂ Group

Abstract

Readily prepared primary, secondary, and tertiary difluoroallylic alcohols, derived from commercially available and inexpensive 2,2,2-trifluoroethanol, have been transformed into a range of difluoroallylic methyl ethers containing appropriate carbanion-stabilizing substituents. The [2,3]-Wittig rearrangements of these difluoroallylic ethers have been achieved cleanly, using lithium diisopropylamide in tetrahydrofuran at −30 °C, in excellent (secondary ether substrates) to good (primary and tertiary ether substrates) yields. Consequently, the approach allows convenient and rapid access to products containing a mid-chain CF2 group and with a useful level of functionality.