CO Gas-free Intramolecular Cyclocarbonylation Reactions of Haloarenes Having a C-Nucleophile through CO-Relay between Rhodium and Palladium

We describe transfer carbonylation reactions of 2-bromoarenes that contain a carbon-nucleophile using aldehydes as a substitute for CO, leading to the formation of indanone derivatives. The transformation proceeds efficiently under Rh^I/Pd⁰-hybrid catalytic conditions consisting of two discrete transition metals, rhodium and palladium, which catalyze the decarbonylation of aldehydes and the subsequent carbonylation of bromoarenes using the resulting carbonyl moiety, respectively. The majority of the abstracted CO is transferred directly to the product via a CO-relay process from rhodium to palladium.