Highly Stereoselective Pd/In-Mediated Allylation

Electrophilic pi-allyl palladium complexes can be converted to nucleophilic allyl species in the presence of indium (I) iodide. We have been investigating the stereoselectivity of the redox transmetallation with indium. The reaction of cyclic vinyl oxazolidinones with Pd(0)/InI and aldehydes affords a highly regio- and stereoselective product. The product stereochemistry was confirmed by X-ray crystallography.

We have found that the indium intermediate equilibrates readily, thus the same product was obtained starting from either the cis or the trans benzoates shown below.

The catalytic enantioselective version of this reaction can be carried out using a desymmetrization strategy. Employing the meso-bis benzoate and the Trost chiral bisphosphine ligand, high enantioselectivity was achieved.