Revisiting Nickel-Catalyzed Carbonylations: (Unexpected) Observation of Substrate-Dependent Mechanistic Differences

The (hydroxy)­carbonylation of tertiary aliphatic alcohols and their corresponding olefins with a Ni-based catalyst system is investigated. This study builds on a previous mechanistic investigation into the Ni-catalyzed carbonylation of alcohols. The findings differed from what could be explained with the previously reported mechanisms, prompting this in-depth mechanistic study. Combined experimental and quantum chemical efforts are crucial for the rationalization of the observed reactivities and ultimately help reveal another isobutene-based catalytic pathway, accessible with these substrates. This study further expands the knowledge about Ni-catalyzed carbonylation reactions, which have been known for more than 70 years but were scarcely studied in detail from a mechanistic point of view.