Catalytic Asymmetric Defluorinative Allylation of Silyl Enol Ethers

The stereocontrolled installation of alkyl fragments at the alpha position of ketones is a fundamental yet unresolved transformation in organic chemistry. Herein we report a new catalytic methodology able to construct alpha-allyl ketones via defluorinative allylation of silyl enol ethers in a regio- diastereo- and enantioselective manner. The protocol leverages the unique features of the fluorine atom to simultaneously act as leaving group and to activate the fluorophilic nucleophile via a SiF interaction. A series of spectroscopic, electroanalytic and kinetic experiments demonstrate the crucial interplay of the Si–F interaction for successful reactivity and selectivity. The generality of the transformation is demonstrated by synthesising a wide set of structurally diverse alpha-allylated ketones bearing two contiguous stereocenters. Remarkably, the catalytic protocol is amenable for the allylation of biologically significant natural products.