Synthesis of Five- and Six-Membered Benzocyciic Ketones through Intramolecular Alkene Hydroacylation Catalyzed by Nickel(0)/N-Heterocyclic Carbenes

摘要

Transition-metal-catalyzed hydroacylation has been accepted as a promising synthetic method to form carbon-carbon bonds between an aldehyde and unsaturated compounds, such as alkenes, alkynes, and ketones. A number of catalyst systems have been developed, and high enatio-, regio-, and chemo-selectivity has been achieved. Despite these extensive efforts and praiseworthy results, an inevitable side reaction persists: decarbonylation from an acyl metal intermediate, which causes a decrease in atom-efficiency and a deactivation of the catalyst through the coordination of carbon monoxide (Scheme 1, path a). Major advances in hydroacylation have been associated with the development of strategies to suppress decarbonylation.Thus, in the interest of promoting further progress, it is worthwhile to provide an alternative strategy to avoid decarbonylation.