Site-Selective Alkyl Dehydrogenation of a Coordinated Acylphosphine Ligand

Regio- and stereoselective alkane dehydrogenation is a difficult challenge in organometallic chemistry. Intermolecular reactions of this type typically produce numerous olefin stereo- and regioisomers. Herein, we report our initial investigations into the intramolecular dehydrogenation of a datively bound alkyl ligand, demonstrating the first example of a site-selective dehydrogenation of an unactivated acyclic alkyl group. The alkyl group is located on an acylphosphine ligand that is coordinated to a Cp*IrCl2 monomer. A mechanistic proposal, guided by the isolation of a dimeric iridium complex and supported by computational results, is also described.