Enantioselective construction of remote tertiary carbon–fluorine bonds

The carbon–fluorine bond engenders distinctive physicochemical properties and significant changes to general reactivity. The development of catalytic, enantioselective methods to set stereocentres that contain a benzylic C–F bond is a rapidly evolving goal in synthetic chemistry. Although there have been notable advances that enable the construction of secondary stereocentres that contain both a C–F and a C–H bond on the same carbon, significantly fewer strategies are defined to access stereocentres that incorporate a tertiary C–F bond, especially those remote from pre-existing activating groups. Here we report a general method that establishes C–F tertiary benzylic stereocentres by forging a C–C bond via a Pd-catalysed enantioselective Heck reaction of acyclic alkenyl fluorides with arylboronic acids. This method provides a platform to rapidly incorporate significant functionality about the benzylic tertiary fluoride by virtue of the diversity of both reaction partners, as well as the ability to install the stereocentres remotely from pre-existing functional groups. Although methods exist to construct secondary stereocentres containing both a C–F and C–H bond, the ability to form a tertiary C–F bond, remote from pre-existing activating groups, remains challenging. Now, C–F tertiary, benzylic stereocentres have been constructed through a Pd-catalysed enantioselective Heck reaction of acyclic alkenyl fluorides with arylboronic acids.