hydroacylations

Hydroacylation refers to a class of organometallic reactions in which an aldehyde participates across an unsaturated substrate, typically an alkene or alkyne, to form a carbonyl-containing product such as a ketone. In many procedures, a transition metal catalyst facilitates the insertion of the unsaturated partner into a metal–acyl bond derived from the aldehyde, delivering a new carbon–carbon bond and a ketone upon turnover. Hydroacylation is distinct from hydroformylation, which adds a formyl group across an alkene to give aldehydes.

Mechanistically, many hydroacylations proceed via activation of the aldehyde C–H bond to generate an acyl–metal species, followed by migratory insertion of the unsaturated substrate into the acyl–metal bond, and reductive elimination to release the ketone and regenerate the catalyst. Alternative decarbonylative or concerted pathways can also operate depending on the system.

Substrates include aldehydes and various alkenes or alkynes. Intramolecular hydroacylation can form cyclic ketones and lactones, while intermolecular variants enable coupling of aldehydes with diverse alkenes or alkynes to access acyclic or cyclic ketones. Catalysts reported for hydroacylation include rhodium, ruthenium, iridium, nickel, and cobalt complexes, often bearing chiral ligands to provide enantioenriched products.

Applications span the synthesis of ketones, cyclic frameworks, natural products, and pharmaceutical intermediates. Advantages include atom economy and direct construction of C–C bonds from simple starting materials, though challenges remain in controlling regio- and stereoselectivity, functional-group tolerance, and the cost and availability of catalysts.