Iron-Catalyzed Coupling of Alkenes and Enones: Sakurai–Michael-type Conjugate Addition of Catalytic Allyliron Nucleophiles

[Image: see text] The iron-catalyzed coupling of alkenes and enones through allylic C(sp(3))–H functionalization is reported. This redox-neutral process employs a cyclopentadienyliron(II) dicarbonyl catalyst and simple alkene substrates to generate catalytic allyliron intermediates for 1,4-addition to chalcones and other conjugated enones. The use of 2,4,6-collidine as the base and a combination of triisopropylsilyl triflate and LiNTf(2) as Lewis acids was found to facilitate this transformation under mild, functional group-tolerant conditions. Both electronically unactivated alkenes as well as allylbenzene derivatives could be employed as pronucleophilic coupling partners, as could a range of enones bearing electronically varied substituents.