The Cu-catalyzed enantioselective Kharasch-Sosnovsky allylic oxidation reaction is of high interest due to the fact that the resulting ester product could serve as a precursor to many compounds with varying numbers of chiral centers. Such compounds may be useful in the synthesis of potentially therapeutic compounds. However, enantioselective variants used in the Kharasch-Sosnovsky reaction have shown limited selectivity. Recently, the synthesis of amino acid-based chiral ligands and their subsequent use in the Kharasch-Sosnovsky reaction were attempted in hopes that such ligands would be successful in transferring chirality. Amino acids were specifically used as they are not only inexpensive and readily available but also allow for a range of different potential substrates. L-Valine and salicylaldehyde were used to successfully produce a chiral ligand under basic conditions in a 42.8% yield. The ligand was found to be reproducible and was then used in the Kharasch-Sosnovsky reaction. Attempts to optimize the reaction included variation in solvents, amine additives such as phenylhydrazine, reaction time, and copper source. Although highest yield of 49.6% was achieved using acetone, DBU, and CuCl at room temperature, the analogous reaction using the synthesized ligand resulted in low yields.

Development of a copper catalyzed enantioselective allylic oxidation reaction using chiral amino acid ligands

251st National Meeting (2016)

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