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.