科研之友
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摘要
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 p-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.
