title: Mechanistic origin of cross-coupling selectivity in Ni-catalysed Tishchenko reactions.
abstract: Mechanistic studies have been performed for the recently developed, Ni-catalysed selective cross-coupling reaction between aryl and alkyl aldehydes. A mono-carbonyl activation (MCA) mechanism (in which one of the carbonyl groups is activated by oxidative addition) was found to be the most favourable pathway, and the rate-determining step is oxidative addition. Analysing the origin of the observed cross-coupling selectivity, we found the most favourable carbonyl activation step requires both coordination of the aryl aldehyde and oxidative addition of the alkyl aldehyde. Therefore, the stronger π-accepting ability of the aryl aldehyde (relative to alkyl aldehyde) and the ease of oxidative addition of the alkyl aldehyde (relative to aryl aldehyde) are responsible for the cross-coupling selectivity.
authors.affiliation: Department of Chemistry, University of Science and Technology of China, Hefei, PR China.
authors.forename: Haizhu
authors.initials: H
authors.lastname: Yu
authors.forename: Yao
authors.initials: Y
authors.lastname: Fu