N Dissociation vs Reversible 1,2-Methyl Migration in PCP Cobalt(I) Complexes in the Stereoselective Isomerization () of Allyl Ethers.

With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PCP pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PCP)Co)-μ-N][BAr ] () mainly favors the -isomer of the enol ether, the corresponding methyl complex [(PCP)CoMe] () mostly gives the -isomer. The dichotomy in selectivity was investigated computationally, revealing important contributions from the substituents on the metal (N vs Me), including a 1,2-alkyl migration from cobalt to the N-heterocyclic carbene (NHC) of the methyl substituent, which is further explored in this report.