(NHC)NiH‐Catalyzed Regiodivergent Cross‐Hydroalkenylation of Vinyl Ethers with α‐Olefins: Syntheses of 1,2‐ and 1,3‐Disubstituted Allyl Ethers

Cross‐hydroalkenylation of a vinyl ether ( 1 ) with an α‐olefin ( 2 ) was first achieved by a set of NHC‐Ni(allyl)]BAr^F (NHC=N‐heterocyclic carbene) catalysts. Both 1,2‐ and 1,3‐disubstituted allyl ethers were obtained, highly selectively, by using NHCs of different sizes. In contrast, the chemoselectivity (i.e., 1 as acceptor and 2 as donor) was controlled mostly by electronic effects through the catalyst–substrate interaction. Sterically bulkier alkenes ( 2 ) were used as preferred donors compared to smaller alkenes. This electronic effect also served as a basis for the first tail‐to‐head cross‐hydroalkenylations of 1 with either a vinyl silane or boronic ester.