Cross couplings between simple allylic
alcohols and aryl and vinyl
boronic acids are efficiently catalyzed by nickel(0) catalysts and
bidentate N-heterocyclic carbene/phosphine ligands.
The bidentate nature of the ligand is shown to extend catalyst lifetime
and enable high yields of the corresponding cross-coupling products.
X-ray crystallography confirms the bidentate nature of the ligand
scaffold. Multistep cross coupling-alkene/alkyne insertions reactions
are also conducted and the bidentate nature of the substrate makes
the pendant phosphine of the ligand unnecessary.
Amination of allylic alcohols is facilitated via cooperative catalysis. Catalytic Ti(O- i-Pr) is shown to dramatically increase the rate of nickel-catalyzed allylic amination, and mechanistic experiments confirm activation of the allylic alcohol by titanium. Aminations of primary and secondary allylic alcohols are demonstrated with a variety of amine nucleophiles. Diene-containing substrates also cyclize onto the nickel allyl intermediate prior to amination, generating carbocyclic amine products. This tandem process is only achieved under our cooperative catalytic system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.