Rhodium-catalyzed synthesis of esters from aryl iodides and alcohols: use of alcohols with/without the assistance of aldehydes as carbon monoxide and nucleophile sources

Since the rst report by Heck et al. on the palladium-catalyzed reaction of carbon monoxide with aryl halides and alcohols or amines, transition metal catalyzed cross-coupling reactions have been developed as a valuable method for creating carbon– carbon bonds. In particular, rhodium-catalyzed carbonylation with a variety of substrates has been studied. These reactions require the addition of CO to the substrate, and are typically carried out with carbon monoxide gas. However, the use of carbon monoxide is not recommended due to its toxicity and difficulty in handling. Thus, the use of CO-releasing reagents, such as formic acid derivatives, oxiranes, and aldehydes has been studied. Recently, Jun et al. reported the Pd/C-catalyzed carbonylative esterication of a primary alcohol with aryl chlorides in the presence of NaF. Previously, we reported the use of an alcohol as a CO source in the rhodium-catalyzed Pauson– Khand reaction of enynes and as a source of hydrogen in the Rh-catalyzed reductive cyclization of enynes. Thus, in the presence of a rhodium catalyst, an alcohol can be used as a CO or hydrogen source as well as a reaction medium. We therefore decided to explore the use of an alcohol as a CO and nucleophile source, in a reaction with aryl iodides, during the synthesis of esters (Scheme 1).