Highly Selective Coupling of Alkenes and Aldehydes Catalyzed by [Ni(NHC){P(OPh) 3 }]: Synergy between a Strong σ Donor and a Strong π Acceptor

Give and take: Both a strong electron donor (1) and a strong electron acceptor (P(OPh)3) are necessary for a highly selective, nickel-catalyzed coupling reaction between alkenes, aldehydes, and silyl triflates (see scheme; cod=cycloocta-1,5-diene, Tf=trifluoromethanesulfonyl). This synergistic effect may also be useful in other transformations catalyzed by NHC–metal complexes (NHC=N-heterocyclic carbene).