Carbonyl Allylation in the Absence of Preformed Allyl Metal Reagents: Reverse Prenylation via Iridium-Catalyzed Hydrogenative Coupling of Dimethylallene

Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a−12a delivers products of reverse prenylation 1b−12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio-8b. As revealed by 2H NMR analysis, deuterium incorporation is observed at the vinylic position (80% 2H). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents.