Branched-Selective, Catalytic Allene Hydrocarbonation Enabled by Ir(I)/dFppe complexes

The direct addition of C–H bonds across allenes represents an attractive strategy for the construction of allylic frameworks, but controlling the selectivity remains a major challenge. In this Synpacts article, we summarize the development of an Ir(I) catalytic system featuring a perfluorinated bisphosphine ligand, dFppe, which directs the reaction toward branched allylic products with high chemo- and regioselectivity. The method is applicable to several classes of C–H partners, including N-substituted pyrrole carboxamides, furans, and β-unsubstituted acrylamides, and accommodates both mono- and 1,1-disubstituted allenes. As a result, densely substituted products bearing tertiary or all-carbon quaternary centers can be accessed efficiently. Preliminary asymmetric studies with chiral ligands show promising levels of enantioinduction with a pentafluoroaryl-containing bisphosphinite, while DFT calculations indicate that non-covalent interactions involving the fluorinated ligand play a key role in stabilizing the branched-selective reaction pathways.