Exploiting Carbonyl Groups to Control Intermolecular Rhodium-Catalyzed Alkene and Alkyne Hydroacylation

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β-carbonyl-substituted aldehydes are shown
to be exceptional substrates for Rh-catalyzed intermolecular alkene
and alkyne hydroacylation reactions. By using cationic rhodium catalysts
incorporating bisphosphine ligands, efficient and selective reactions
are achieved for β-amido, β-ester, and β-keto aldehyde
substrates, providing a range of synthetically useful 1,3-dicarbonyl
products in excellent yields. A correspondingly broad selection of
alkenes and alkynes can be employed. For alkyne substrates, the use
of a catalyst incorporating the Ampaphos ligand triggers a regioselectivity
switch, allowing both linear and branched isomers to be prepared with
high selectivity in an efficient manner. Structural data, confirming
aldehyde chelation, and a proposed mechanism are provided.